4 Dec 2016

Why must time be a dimension?

“It is old age, rather than death, that is to be contrasted with life. Old age is life’s parody, whereas death transforms life into a destiny: in a way it preserves it by giving it the absolute dimension. Death does away with time.” -Simone de Beauvoir

When we think about how we can move through the Universe, we immediately think of three different directions. Left-or-right, forwards-or-backwards, and upwards-or-downwards: the three independent directions of a Cartesian grid. All three of those count as dimensions, and specifically, as spatial dimensions. But we commonly talk about a fourth dimension of a very different type: time. But what makes time a dimension at all? That’s this week’s Ask Ethan question from Thomas Anderson, who wants to know:

I have always been a little perplexed about the continuum of 3+1 dimensional Space-time. Why is it always 3 [spatial] dimensions plus Time?

Let’s start by looking at the three dimensions of space you’re familiar with.

On the surface of a world like the Earth, two coordinates, like latitude and longitude, are sufficient to define a location. Image credit: Wikimedia Commons user Hellerick.

Here on the surface of the Earth, we normally only need two coordinates to pinpoint our location: latitude and longitude, or where you are along the north-south and east-west axes of Earth. If you’re willing to go underground or above the Earth’s surface, you need a third coordinate — altitude/depth, or where you are along the up-down axis — to describe your location. After all, someone at your exact two-dimensional, latitude-and-longitude location but in a tunnel beneath your feet or in a helicopter overhead isn’t truly at the same location as you. It takes three independent pieces of information to describe your location in space.

Your location in this Universe isn’t just described by spatial coordinates (where), but also by a time coordinate (when). Image credit: Pixabay user rmathews100.

But spacetime is even more complicated than space, and it’s easy to see why. The chair you’re sitting in right now can have its location described by those three coordinates: x, y and z. But it’s also occupied by you right now, as opposed to an hour ago, yesterday or ten years from now. In order to describe an event, knowing where it occurs isn’t enough; you also need to know when, which means you need to know the time coordinate, t. This played a big deal for the first time in relativity, when we were thinking about the issue of simultaneity. Start by thinking of two separate locations connected by a path, with two people walking from each location to the other one.

Two points connected by a 1-dimensional (linear) path. Image credit: Wikimedia Commons user Simeon87.

You can visualize their paths by putting two fingers, one from each hand, at the two starting locations and “walking” them towards their destinations. At some point, they’re going to need to pass by one another, meaning your two fingers are going to have to be in the same spot at the same time. In relativity, this is what’s known as a simultaneous event, and it can only occur when all the space components and all the time components of two different physical objects align.

This is supremely non-controversial, and explains why time needs to be considered as a dimension that we “move” through, the same as any of the spatial dimensions. But it was Einstein’s special theory of relativity that led his former professor, Hermann Minkowski, to devise a formulation that put the three space dimensions and the one time dimension together.

Whether flat or curved, moving through space has implications for moving through time as well. Image credit: Pixabay user Johnson Martin.

We all realize that to move through space requires motion through time; if you’re here, now, you cannot be somewhere else now as well, you can only get there later. In 1905, Einstein’s special relativity taught us that the speed of light is a universal speed limit, and that as you approach it you experience the strange phenomena of time dilation and length contraction. But perhaps the biggest breakthrough came in 1907, when Minkowski realized that Einstein’s relativity had an extraordinary implication: mathematically, time behaves exactly the same as space does, except with a factor of c, the speed of light in vacuum, and a factor of I, the imaginary number √(-1).

An example of a light cone, the three-dimensional surface of all possible light rays arriving at and departing from a point in spacetime. Image credit: Wikimedia Commons user MissMJ.

Putting all of these revelations together yielded a new picture of the Universe, particularly as respects how we move through it.

  • If you’re completely stationary, remaining in the same spatial location, you move through time at its maximal rate.
  • The faster you move through space, the slower you move through time, and the shorter the spatial distances in your direction-of-motion appear to be.
  • And if you were completely massless, you would move at the speed of light, where you would traverse your direction-of-motion instantaneously, and no time would pass for you.

A stationary observer sees time pass normally, but an observer moving rapidly through space will have their clock run slower relative to the stationary observer. Image credit: Michael Schmid of Wikimedia Commons.

From a physics point of view, the implications are astounding. It means that all massless particles are intrinsically stable, since no time can ever pass for them. It means that an unstable particle, like a muon created in the upper atmosphere, can reach the Earth’s surface, despite the fact that multiplying its lifetime (2.2 µs) by the speed of light yields a distance (660 meters) that’s far less than the distance it must travel. And it means that if you had a pair of identical twins and you left one on Earth while the other took a relativistic journey into space, the journeying twin would be much younger upon return, having experienced the passage of less time.

Mark and Scott Kelly at the Johnson Space Center, Houston Texas; one spent a year in space (and aged slightly less) while the other remained on the ground. Image credit: NASA.

As Minkowski said in 1908,

The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.

Today, the formulation of spacetime is even more generic, and encompasses the curvature inherent to space itself, which is how special relativity got generalized. But the reason time is just as good a dimension as space is because we’re always moving through it, and the reason it’s sometimes written as a “1″ in “3+1″ (instead of just treated as another “1″ of the “4″) is because increasing your motion through space decreases your motion through time, and vice versa. (Mathematically, this is where the I comes in.)

Having your camera anticipate the motion of objects through time is just one practical application of the idea of time-as-a-dimension. The remarkable thing is that anyone, regardless of their motion through space relative to anyone else, will see these same rules, these same effects and these same consequences. If time weren’t a dimension in this exact way, the laws of relativity would be invalid, and there might yet be a valid concept such as absolute space. We need the dimensionality of time for physics to work the way it does, and yet our Universe provides for it oh so well. Be proud to give it a “+1” in all you do.

2 Dec 2016

Alien life could thrive in the clouds of failed stars

Ashampoo_Snap_2016.12.02_11h29m02s_002_There’s an abundant new swath of cosmic real estate that life could call home – and the views would be spectacular. Floating out by themselves in the Milky Way galaxy are perhaps a billion cold brown dwarfs, objects many times as massive as Jupiter but not big enough to ignite as a star. According to a new study, layers of their upper atmospheres sit at temperatures and pressures resembling those on Earth, and could host microbes that surf on thermal updrafts.

The idea expands the concept of a habitable zone to include a vast population of worlds that had previously gone unconsidered. “You don’t necessarily need to have a terrestrial planet with a surface,” says Jack Yates, a planetary scientist at the University of Edinburgh in the United Kingdom, who led the study.

Atmospheric life isn’t just for the birds. For decades, biologists have known about microbes that drift in the winds high above Earth’s surface. And in 1976, Carl Sagan envisioned the kind of ecosystem that could evolve in the upper layers of Jupiter, fueled by sunlight. You could have sky plankton: small organisms he called “sinkers.” Other organisms could be balloon-like “floaters,” which would rise and fall in the atmosphere by manipulating their body pressure. In the years since, astronomers have also considered the prospects of microbes in the carbon dioxide atmosphere above Venus’s inhospitable surface.

Yates and his colleagues applied the same thinking to a kind of world Sagan didn’t know about. Discovered in 2011, some cold brown dwarfs have surfaces roughly at room temperature or below; lower layers would be downright comfortable. In March 2013, astronomers discovered WISE 0855-0714, a brown dwarf only seven light years away that seems to have water clouds in its atmosphere. Yates and his colleagues set out to update Sagan’s calculations and to identify the sizes, densities, and life strategies of microbes that could manage to stay aloft in the habitable region of an enormous atmosphere of predominantly hydrogen gas. Sink too low and you are cooked or crushed. Rise too high and you might freeze.

On such a world, small sinkers like the microbes in Earth’s atmosphere or even smaller would have a better chance than Sagan’s floaters, the researchers will report in an upcoming issue of the Astrophysical Journal. But a lot depends on the weather: if upwelling winds are powerful on free-floating brown dwarfs, as seems to be true in the bands of gas giants like Jupiter and Saturn, heavier creatures can carve out a niche. In the absence of sunlight, they could feed on chemical nutrients. Observations of cold brown dwarf atmospheres reveal most of the ingredients Earth life depends on: carbon, hydrogen, nitrogen, and oxygen, though perhaps not phosphorous.

The idea is speculative but worth considering, says Duncan Forgan, an astrobiologist at the University of St. Andrews in the United Kingdom, who did not participate in the study but says he is close to the team. “It really opens up the field in terms of the number of objects that we might then think, well, these are habitable regions.”

So far, only a few dozen cold brown dwarfs have been discovered, though statistics suggest there should be about ten within thirty light-years of Earth. These should be ripe targets for the James Webb Space Telescope (JWST), which is sensitive in the infrared where brown dwarfs shine brightest. After it launches in 2018, JWST should reveal the weather and the composition of their atmospheres, says Jackie Faherty, an astronomer at the Carnegie Institution for Science in Washington, D.C. “We’re going to start getting gorgeous spectra of these objects,” she says. “This is making me think about it.”

Testing for life would require anticipating a strong spectral signature of microbe byproducts like methane or oxygen, and then differentiating it from other processes, Faherty says. Another issue would be explaining how life could arise in an environment that lacks the water-rock interfaces, like hydrothermal vents, where life is thought to have begun on Earth. Perhaps life could develop through chemical reactions on the surfaces of dust grains in the brown dwarf’s atmosphere, or perhaps it gained a foothold after arriving as a hitchhiker on an asteroid. “Having little microbes that float in and out of a brown dwarf atmosphere is great,” Forgan says. “But you’ve got to get them there first.”

Indian astrophysicist wins 10-year-old bet on dark energy

Ashampoo_Snap_2016.12.02_11h25m18s_001_David Wiltshire has gifted a decorative lamp worth $200 to Thanu Padmanabham.

An Indian astrophysicist, named Thanu Padmanabham, who extended Albert Einstein’s theory on Dark Energy has won a 10-year-old bet with a New Zealand-based astrophysicist who had challenged him for the theory.

On December 1, the New Zealand astrophysicist, David Wiltshire, from the University of Canterbury, announced that he had conceded the wager to India’s astrophysicist Thanu Padmanabham on the nature of dark energy.

During a planetary talk on December 15, 2006 at the t an international physics symposium in Australia in 2006, Padmanabham challenged the audience stating that in the next ten years there will be no evidence to contradict the hypothesis that dark energy (cosmological constant) is the root cause of accelerated expansion of the universe. That is, dark energy is a mathematical term called the "cosmological constant" that Einstein had initially proposed in his equations, but abandoned.

It was Witlshire who accepted the challenge to disproof Padmanabham’s dark energy theory.

Dark energy was discovered in late 1990s by observing distant exploding stars that are said to push everything in the universe away from everything else. Studies suggest that Dark matter makes up about 72 per cent of the all the matter-energy in the universe, while the visible- matter in the universe including stars, planet and galaxies make up only 4 per cent.

Over the past decade, Padmanabham continued with his calculations, and four years ago Padmanabham with his daughter co-authored a paper in which they derived the numerical value of the cosmological constant.

Under the written terms of the wager, Wiltshire has gifted a decorative lamp worth $200, whose colour output can be altered using a mobile app, to Padmanabham.

Tags: astrophysicist, dark energy, albert einstein

This 6-foot wide asteroid is the smallest ever found Read

smallAstronomers have obtained observations of the smallest asteroid ever characterized in detail. At 2 meters (6 feet) in diameter, the tiny space rock is small enough to be straddled by a person in a hypothetical space-themed sequel to the iconic bomb-riding scene in the movie "Dr. Strangelove."

Interestingly, the asteroid, named 2015 TC25, is also one of the brightest near-Earth asteroids ever discovered. Using data from four different telescopes, a team of astronomers led by Vishnu Reddy, an assistant professor at the University of Arizona's Lunar and Planetary Laboratory, reports that 2015 TC25 reflects about 60 percent of the sunlight that falls on it.

Discovered by the UA's Catalina Sky Survey last October, 2015 TC25 was studied extensively by Earth-based telescopes during a close flyby that saw the micro world sailing past Earth at 128,000 kilometers, a mere third of the distance to the moon.

In a paper published in The Astronomical Journal, Reddy argues that new observations from the NASA Infrared Telescope Facility and Arecibo Planetary Radar show that the surface of 2015 TC25 is similar to a rare type of highly reflective meteorite called an aubrite. Aubrites consist of very bright minerals, mostly silicates, that formed in an oxygen-free, basaltic environment at very high temperatures. Only one out of every 1,000 meteorites that fall on Earth belong to this class.

"This is the first time we have optical, infrared and radar data on such a small asteroid, which is essentially a meteoroid," Reddy said. "You can think of it as a meteorite floating in space that hasn't hit the atmosphere and made it to the ground — yet."

Small near-Earth asteroids such as 2015 TC25 are in the same size range as meteorites that fall on Earth. Astronomers discover them frequently, but not very much is known about them as they are difficult to characterize. By studying such objects in more detail, astronomers hope to better understand the parent bodies from which these meteorites originate.

Asteroids are remaining fragments from the formation of the solar system that mostly orbit the sun between the orbits of Mars and Jupiter today. Near-Earth asteroids are a subset that cross Earth's path. So far, more than 15,000 near-Earth asteroids have been discovered.

Scientists are interested in meteoroids because they are the precursors to meteorites impacting Earth, Reddy said.

"If we can discover and characterize asteroids and meteoroids this small, then we can understand the population of objects from which they originate: large asteroids, which have a much smaller likelihood of impacting Earth," he said. "In the case of 2015 TC25, the likelihood of impacting Earth is fairly small."

The discovery also is the first evidence for an asteroid lacking the typical dust blanket — called regolith — of most larger asteroids. Instead, 2015 TC25 consists essentially of bare rock. The team also discovered that it is one of the fastest-spinning near-Earth asteroids ever observed, completing a rotation every two minutes.

Probably, 2015 TC25 is what planetary scientists call monolithic, meaning it is more similar to a "solid rock" type of object than a "rubble pile" type of object like many large asteroids, which often consist of many types of rocks held together by gravity and friction. Bennu, the object of the UA-led OSIRIS-REx sample return mission, is believed to be the latter type.

As far as the little asteroid's origin is concerned, Reddy believes it probably was chipped off by another impacting rock from its parent, 44 Nysa, a main-belt asteroid large enough to cover most of Los Angeles.

"Being able to observe small asteroids like this one is like looking at samples in space before they hit the atmosphere and make it to the ground," Reddy say. "It also gives us a first look at their surfaces in pristine condition before they fall through the atmosphere."

The telescope consortium used in this project includes University of Hawaii/NASA IRTF, USRA/Arecibo Planetary Radar, New Mexico Institute of Mining and Technology/Magdalena Ridge Observatory, Northern Arizona University and Lowell Observatory/Discovery Channel Telescope. Reddy's research on 2015 TC25 is funded by NASA's Near-Earth Object Observations program.

'Shockingly' cold gas cloud surrounding early giant galaxy surprises scientists

Ashampoo_Snap_2016.12.01_22h53m42s_001_The discovery of an enormous reservoir of ultra-cold gas surrounding a distant galaxy has reshaped our scientific understanding of how stars and galaxies formed in the early universe.

An international team of scientists detected the huge halo of gas, 100 billion times the mass of our Sun, surrounding the Spider web galaxy, a massive galaxy surrounded by smaller galaxies about 10 billion light-years from Earth.

Until now, it was thought early galaxies were formed by the merging of smaller galaxies, but the growth of the Spiderweb galaxy appears to be fuelled by the cold cloud, scientists reported today in the journal Science.

"This completely changes the way we think that clusters of galaxies form," said Professor Ray Norris, an astrophysicist at CSIRO and Western Sydney University and co-author of the study.

"We're realising that lots of things we thought we knew about the universe are really based on what's going on in the modern universe.

"As we learn more and more about the early universe, we're realising there's quite a few things that are pretty different back there."

Ashampoo_Snap_2016.12.01_22h54m18s_002_The research team expected the cluster of galaxies they were looking at, which formed about 3 billion years after the Big Bang, to be hot and violent as galaxies collided and merged.

But instead, they found that the central, larger galaxy was surrounded by an "enormous halo" of very cold gas with stars forming inside it.

"Nobody expected to see that," Professor Norris said.

The gas cloud, which had a temperature of about -200 degrees Celsius and was made up largely of carbon monoxide was a "major component" of star creation, he said, though the cannibalisation of small galaxies also played a part.

The discovery was made using Australia's Compact Array, a five-dish radio telescope in New South Wales, and the Very Long Array in New Mexico, to detect the carbon monoxide in the cold gas cloud.

While several telescopes around the world can detect carbon monoxide, Professor Norris said the wavelength range of the Compact Array made it the only one able to detect it at such a large distance from Earth.

The combined use of the VLA (which imaged individual galaxies in the cluster) and the Compact Array (which detected the gas) formed a picture of what was going on in the distant cluster.

"It's actually a combination of using these two telescopes together that really finally showed us what's going on," Professor Norris said.

More questions than answers

The discovery raises further questions about the nature of the early universe and the formation of stars.

Ashampoo_Snap_2016.12.01_22h54m41s_003_Professor Norris said it was not yet clear exactly how the cold gas cloud came to be around the Spiderweb galaxy, but that it couldn't have come from the Big Bang because of its high carbon monoxide content.

"This gas has to have come from galaxies, even if it's early in the lifetime of the universe. So we really don't know [where it came from]. This is another really good question," he said.

The next step will be to image other clusters of galaxies from a similar time period to see whether they're also surrounded by vast gaseous reservoirs.

The Spiderweb galaxy, seen here in the centre of the galaxy cluster, as captured by the Hubble Space Telescope. Supplied: NASA/ESA/G. Miley/R. Overzier/ACS Science Team

"The impetus will be to look for other examples of this. I'm sure we, and other groups, will start looking at other clusters and my guess is we'll probably see similar things in other clusters now," Professor Norris said.

He said the discovery deepens our scientific understanding of those first billions of years after the Big Bang, when the universe was still forming.

"There's a number of ideas that, if you asked astronomers 10 years ago, they'd tell you it's this or that, and we've had to abandon some of those ideas in the early universe," he said.

"So this new discovery, it fits into the context of things we're seeing.

1 Dec 2016

Tangled threads weave through cosmic oddity

New observations from the NASA/ESA Hubble Space Telescope have revealed the intricate structure of the galaxy NGC 4696 in greater detail than ever before. The elliptical galaxy is a beautiful cosmic oddity with a bright core wrapped in system of dark, swirling, thread-like filaments.

NGC 4696 is a member of the Centaurus galaxy cluster, a swarm of hundreds of galaxies all sitting together, bound together by gravity, about 150 million light-years from Earth and located in the constellation of Centaurus.

Right ascension 12h 48m 49.3s | Declination −41° 18′ 40″ | Mag +11.4

Despite the cluster’s size, NGC 4696 still manages to stand out from its companions — it is the cluster’s brightest member, known for obvious reasons as the Brightest Cluster Galaxy . This puts it in the same category as some of the biggest and brightest galaxies known in the Universe.

Even if NGC 4696 keeps impressive company, it has a further distinction: the galaxy’s unique structure. Previous observations have revealed curling filaments that stretch out from its main body and carve out a cosmic question mark in the sky (heic1013), the dark tendrils encircling a brightly glowing centre.

An international team of scientists, led by astronomers from the University of Cambridge, UK, have now used new observations from the NASA/ESA Hubble Space Telescope to explore this thread-like structure in more detail. They found that each of the dusty filaments has a width of about 200 light-years, and a density some 10 times greater than the surrounding gas. These filaments knit together and spiral inwards towards the centre of NGC 4696, connecting the galaxy’s constituent gas to its core.

In fact, it seems that the galaxy’s core is actually responsible for the shape and positioning of the filaments themselves. At the centre of NGC 4696 lurks an active supermassive black hole. This floods the galaxy’s inner regions with energy, heating the gas there and sending streams of heated material outwards.

It appears that these hot streams of gas bubble outwards, dragging the filamentary material with them as they go. The galaxy’s magnetic field is also swept out with this bubbling motion, constraining and sculpting the material within the filaments.

At the very centre of the galaxy, the filaments loop and curl inwards in an intriguing spiral shape, swirling around the supermassive black hole at such a distance that they are dragged into and eventually consumed by the black hole itself.

Understanding more about filamentary galaxies such as NGC 4696 may help us to better understand why so many massive galaxies near to us in the Universe appear to be dead; rather than forming new-born stars from their vast reserves of gas and dust, they instead sit quietly, and are mostly populated with old and aging stars. This is the case with NGC 4696. It may be that the magnetic structure flowing throughout the galaxy stops the gas from creating new stars.

30 Nov 2016

The astronomy program for December 2016

Running time: 33 minutes

Please subscribe & share this program with your friends

THE ORION NEBULA is a fine target for astro-photographers, and is known worldwide.

In this program we learn all about the white hot Trapezium stars, Star birth in the nebula, Brown dwarfs, and star so small they are classed as planets. 

You also learn how to use the constellation of Orion as a signpost to nearby constellations this Winter.

YearbookAcknowledgements: The European Southern Observatory, and Hubble Telescope science team for providing further educational items for Richard Pearson’s outreach work.

The bright comet 45P/Honda-Markos-Pajdusa which will be easily visible in binoculars from February 2017 onwards. The star chart shows you where to look for the comet through December 206 to March 2017.

Astronomy & Space is now in its 4th year, and remains a very popular program.

When book publishers Pan McMillan decided not to continue publishing Patrick Moore’s Yearbook of Astronomy, it looked as though the annual book would be lost entirely after 60 years. I am pleased to announce that  after contacting author Brian Jones, and working together, we have found a new publisher to save this splendid book for future generations. This is one legacy left for all of us by Patrick Moore; you to can ensure that Patrick Moore’s Yearbook of Astronomy is safe by buying it when it goes into book shops in 2017.

26 Nov 2016

NASA’s Cassini space probe images Prometheus

PIA20508Prometheus is an inner satellite of Saturn. It was discovered in 1980 (some time before October 25) from photos taken by the Voyager 1 probe, and was provisionally designated S/1980 S 27. In late 1985 it was officially named after Prometheus, a Titan in Greek mythology

Ashampoo_Snap_2016.11.26_22h30m25s_001_

Surface features are visible on Saturn's moon Prometheus in this view from NASA's Cassini spacecraft. Most of Cassini's images of Prometheus are too distant to resolve individual craters, making views like this a rare treat.

Saturn's narrow F ring, which makes a diagonal line beginning at top centre, appears bright and bold in some Cassini views, but not here. Since the sun is nearly behind Cassini in this image, most of the light hitting the F ring is being scattered away from the camera, making it appear dim. Light-scattering behaviour like this is typical of rings comprised of small particles, such as the F ring.

This view looks toward the unilluminated side of the rings from about 14 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 24, 2016.

The view was acquired at a distance of approximately 226,000 miles (364,000 kilometres) from Prometheus and at a sun-Prometheus-spacecraft, or phase, angle of 51 degrees. Image scale is 1.2 miles (2 kilometres) per pixel.

The November program: The Clouds of Magellan

Running time 30 Minutes

ALSO SEE OUR PAST SHOWS RUNNING DOWN THE SIDE COLUMNS

Visible primarily in the southern hemisphere the Magellanic clouds are an attraction for astronomers because they are at the same distance from the observer, and the large variety of exotic objects they contain. Supernova remnants, star clusters, globular clusters, Cepheid-variables and some stars that are record breakers like S-Doradus that is a million times more luminous than our Sun.

The astronomers at the Armagh Observatory in northern ireland has a long history of observing the clouds from the Boyden Observatory in South Africa before the founding of the European Southern Observatory in northern Chile.

In this program Richard Pearson FRAS takes us on a guided tour of the Armagh Observatory and the clouds themselves.

For foreign viewers, the Program Script is below, click on the document to open and read. This will help you to follow the program …

Did a solar storm damage Earth’s magnetic field?

newcoronalma

A review of data, relating to the summer of 2015, suggests a solar storm struck the Earth’s magnetic field. This unprecedented event lasted a couple of hours, and it could have shrunk the Earth’s magnetosphere.

The collected data, reported this month by astrophysicists and highlighted by Wired, indicated that a giant cloud of fast-moving plasma from the Sun struck the Earth’s magnetic field (or ‘magnetosphere’) shrunk from 11 times the Earth’s radius to just four for the two hour period.

The magnetosphere is the region of space surrounding an astronomical object (in this case, our planet) where charged particles are controlled by that object's magnetic field. To give an idea of the strength of the field, NASA scientists have suggested the Earth's magneto tail may cause "dust storms" on the Moon. The storms are created through the potential magnetic difference between the day side and the night side of the moon.

The review of the 2015 event suggests a solar storm of such intensity passed Earth’s magnetosphere (which provides a natural defence against cosmic radiation). The impact of this storm was to hit technology in several regions of the Northern hemisphere through electromagnetic pulses. A solar storm (or solar flare) is a sudden flash of brightness observed near the Sun's surface. It involves a very broad spectrum of energy emissions.

Scientists, Laboratory Roots reports, are concerned the event has put a permanent dent in the Earth’s magnetic field. This is concerning should further events of this magnitude occur in the future, since the magnetic field is our main protection against solar radiation. This doesn’t mean immediate harm to life but such events could further damage electrical equipment and there is a risk, in some areas, of increased skin cancer. And this is all dependent upon future solar storms of a similar magnitude.

The research indicates humanity must be mindful of our magnetic field and the role it plays. However, there isn’t much we can do to protect the planet other than continue to monitor.

The event has been described in the journal Physical Review Letters. The paper is titled “Transient Weakening of Earth’s Magnetic Shield Probed by a Cosmic Ray Burst.”

----------------------------------------------------------------------------------------------------

The GRAPES-3 tracking muon telescope in Ooty, India measures muon intensity at high cutoff rigidities (15–24 GV) along nine independent directions covering 2.3 sr. The arrival of a coronal mass ejection on 22 June 2015 18:40 UT had triggered a severe G4-class geomagnetic storm (storm). Starting 19:00 UT, the GRAPES-3 muon telescope recorded a 2 h high-energy (   ) burst of galactic cosmic rays (GCRs) that was strongly correlated with a 40 nT surge in the interplanetary magnetic field (IMF). Simulations have shown that a large ( ) compression of the IMF to 680 nT, followed by reconnection with the geomagnetic field (GMF) leading to lower cutoff rigidities could generate this burst. Here, 680 nT represents a short-term change in GMF around Earth, averaged over 7 times its volume. The GCRs, due to lowering of cutoff rigidities, were deflected from Earth’s day side by   in longitude, offering a natural explanation of its night-time detection by the GRAPES-3. The simultaneous occurrence of the burst in all nine directions suggests its origin close to Earth. It also indicates a transient weakening of Earth’s magnetic shield, and may hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth, and endanger the lives of the astronauts in space.

medium medium2

24 Nov 2016

Two-year extensions confirmed for ESA's science missions

Solar_System_A1_poster_20_nov.2012

ESA's Science Programme Committee (SPC) has today confirmed two-year mission extensions for nine scientific missions in which the Agency is participating. This secures their operations until the end of 2018.

After a comprehensive review of their current operational status and the likely scientific return from each mission, the SPC decided to extend the operation of six ESA-led missions (Cluster, INTEGRAL, Mars Express, PROBA-2, SOHO and XMM-Newton) from 1 January 2017 to 31 December 2018.

The go-ahead was also given to continue ESA's contributions to the operations of three international collaborative missions: the Hubble Space Telescope and the Interface Region Imaging Spectrograph (IRIS), which are both led by NASA, as well as Hinode, which is a Japanese-led mission.

Every two years, all missions whose approved operations end within the following four years are subject to review by the advisory structure of the Science Directorate. Extensions are granted to missions that satisfy the established criteria for operational status and science return, subject to the level of financial resources available in the science programme. These extensions are valid for the following four years, subject to a mid-term review and confirmation after two years.

mars-express-marsis-radar-instrument

For the current cycle, the committee deferred any decision for the period 2019-2020 until after the meeting of the ESA Council at Ministerial Level, which is being held in Lucerne, Switzerland, 1–2 December. Among many decisions to be taken, the ESA Council will decide the longer-term budget of the science programme.

Science enabled

Extensions for SOHO, PROBA-2 and Hinode, and the continued contribution to IRIS, will ensure that our Sun is closely observed as it continues to head towards an unusually weak minimum of sunspot and flare activity.

Meanwhile, the Cluster quartet will measure the effects of this changing activity nearer to home, as they visit new regions of Earth's magnetosphere and operate simultaneously with other solar-terrestrial missions.

Mars Express has been in operation since December 2003 and it continues to study many different aspects of the Red Planet's atmosphere, surface and moons. Its data will complement measurements made by ESA's Trace Gas Orbiter, which arrived at Mars in October 2016.

XMM-Newton, the Hubble Space Telescope and INTEGRAL will continue to provide complementary observations of the Universe at many different wavelengths. These will include studies of the Solar System, planets orbiting distant stars, exploding stars, black holes, and the evolution of galaxies and the Universe.

23 Nov 2016

It turns out the Sun is more cooler than we previously thought

Ashampoo_Snap_2016.11.23_21h24m04s_001_Article: The Mount Wilson Observatory S-index of the Sun

Authors: Ricky Egeland, Willie Soon, Sallie Baliunas, Jeffrey C. Hall, Alexei A. Pevtsov, and Luca Bertello

First author’s institutions: High Altitude Observatory; Montana State University

One of the few certainties that we have as humans is that the Sun always comes and goes, always in intervals of 24 hours, and will continue to do so for the next 5 billion years or so. Owing to this familiar cycle, we sometimes take for granted that our host star is not itself completely stable. It is active, and this activity shapes the evolution the solar system and life on Earth. Because we use the Sun as a reference for other stars, it is thus crucial that we measure its activity as accurately and precisely as possible.

Blame magnetic fields

Stars are big balls of hot gas with lots of moving parts. The ones that are similar to the Sun (i.e., solar-type stars) have large convective atmospheres, which act just like boiling water inside a cooking pot. The convective circulation of plasma generates magnetic fields, and the stellar rotation, in turn, makes field lines wrap around the star, creating a stellar dynamo. When the magnetic field lines concentrate, they produce dark spots in the stellar surface and spectacular mass ejections; the activity of a star is measured by the strength of these episodes.

Ashampoo_Snap_2016.11.23_21h24m44s_002_One precise and accurate way of assessing stellar activity uses the features in stellar spectrum known as the Ca II H & K lines. Their strength can be easily measured with spectrometers, and are then translated into a ratio called the S-index (the higher it is, the more active the star). The most famous survey of stellar activity is the HK Project at Mount Wilson Observatory (MWO), which consisted on assessing S-index of many stars in the sky, and ended up becoming the standard calibration for current studies on activity. The problem is that not all observations are carried out with the same instrument, and hence systematic errors start to become a serious problem.

Context is key

In order to understand the role of activity in the physics of stellar and planetary evolution, it is important to place the Sun, the one star we know best, in the same context as the others. In today’s paper, the authors aim to precisely and accurately measure its activity using spectroscopic observations of the Moon — which reflects sunlight — obtained with the same instrument employed at the MWO.

Sun-like stars have activity cycles with periods of the order of a few years. The solar cycle has an 11-year period, encompassing a minimum and a maximum. The authors directly measured the minimum, maximum and mean S-index of the solar cycle 23 (1996 – 2007, although the MWO data goes only up to 2003), and found that they were significantly lower than previous estimates of the same cycle. This result shows that, when using different instruments, systematic errors plague the measurements of activity, but the good news is that now we can correct them by applying a better calibration with results from today’s paper.

Ashampoo_Snap_2016.11.23_21h25m11s_003_

Well, now that we have dealt with accuracy, what about precision? As it turns out, there is no lack of solar activity data in the literature, which are now correctly calibrated. The authors used them to constrain the solar activity minimum, maximum and mean values within less than 1% for all indexes.

Effects on future studies

So, the Sun is slightly less active than we previously measured, and this impacts our understanding of solar-type stars the most. By correctly placing our star in the context of others, we can better assess how common it is, which helps us answer questions about the conditions necessary for life to emerge and how it evolves along with the star. These results also rectify some inconsistencies previously observed in the activity of solar-type stars, and again reminds us of a critical aspect of science: systematics matter. The article itself will serve as a guide on measuring stellar activity, paving the way towards better practices in the field.

22 Nov 2016

Mars ice deposit holds as much water as Lake Superior

Ashampoo_Snap_2016.11.22_22h53m07s_003_Frozen beneath a region of cracked and pitted plains on Mars lies about as much water as what's in Lake Superior, largest of the Great Lakes, researchers using NASA's Mars Reconnaissance Orbiter have determined.

Scientists examined part of Mars' Utopia Planitia region, in the mid-northern latitudes, with the orbiter's ground-penetrating Shallow Radar (SHARAD) instrument. Analyses of data from more than 600 overhead passes with the on-board radar instrument reveal a deposit more extensive in area than the state of New Mexico. The deposit ranges in thickness from about 260 feet (80 meters) to about 560 feet (170 meters), with a composition that's 50 to 85 percent water ice, mixed with dust or larger rocky particles.

At the latitude of this deposit -- about halfway from the equator to the pole -- water ice cannot persist on the surface of Mars today. It sublimes into water vapour in the planet's thin, dry atmosphere. The Utopia deposit is shielded from the atmosphere by a soil covering estimated to be about 3 to 33 feet (1 to 10 meters) thick.

"This deposit probably formed as snowfall accumulating into an ice sheet mixed with dust during a period in Mars history when the planet's axis was more tilted than it is today," said Cassie Stuurman of the Institute for Geophysics at the University of Texas, Austin. She is the lead author of a report in the journal Geophysical Research Letters.

Mars today, with an axial tilt of 25 degrees, accumulates large amounts of water ice at the poles. In cycles lasting about 120,000 years, the tilt varies to nearly twice that much, heating the poles and driving ice to middle latitudes. Climate modelling and previous findings of buried, mid-latitude ice indicate that frozen water accumulates away from the poles during high-tilt periods.

Martian Water as a Future Resource

The name Utopia Planitia translates loosely as the "plains of paradise." The newly surveyed ice deposit spans latitudes from 39 to 49 degrees within the plains. It represents less than one percent of all known water ice on Mars, but it more than doubles the volume of thick, buried ice sheets known in the northern plains. Ice deposits close to the surface are being considered as a resource for astronauts.

"This deposit is probably more accessible than most water ice on Mars, because it is at a relatively low latitude and it lies in a flat, smooth area where landing a spacecraft would be easier than at some of the other areas with buried ice," said Jack Holt of the University of Texas, a co-author of the Utopia paper who is a SHARAD co-investigator and has previously used radar to study Martian ice in buried glaciers and the polar caps.

Ashampoo_Snap_2016.11.22_22h52m44s_002_The Utopian water is all frozen now. If there were a melted layer -- which would be significant for the possibility of life on Mars -- it would have been evident in the radar scans. However, some melting can't be ruled out during different climate conditions when the planet's axis was more tilted. "Where water ice has been around for a long time, we just don't know whether there could have been enough liquid water at some point for supporting microbial life," Holt said.

Utopia Planitia is a basin with a diameter of about 2,050 miles (3,300 kilometres), resulting from a major impact early in Mars' history and subsequently filled. NASA sent the Viking 2 Lander to a site near the centre of Utopia in 1976. The portion examined by Stuurman and colleagues lies southwest of that long-silent lander.

Use of the Italian-built SHARAD instrument for examining part of Utopia Planitia was prompted by Gordon Osinski at Western University in Ontario, Canada, a co-author of the study. For many years, he and other researchers have been intrigued by ground-surface patterns there such as polygonal cracking and rimless pits called scalloped depressions -- "like someone took an ice-cream scoop to the ground," said Stuurman, who started this project while a student at Western.

Clue from Canada

In the Canadian Arctic, similar landforms are indicative of ground ice, Osinski noted, "but there was an outstanding question as to whether any ice was still present at the Martian Utopia or whether it had been lost over the millions of years since the formation of these polygons and depressions."

The large volume of ice detected with SHARAD advances understanding about Mars' history and identifies a possible resource for future use.

Why do massive stars lose gas as they evolve? Mira supercomputer may provide answers

Ashampoo_Snap_2016.11.22_22h05m15s_001_Scientists believe they're close to understanding why massive stars lose mass in the form of gas as they evolve. The only problem: a lack of computing power.

The processing power required to run models simulating the evolution of massive stars is immense. But scientists with the Kavli Institute for Theoretical Physics, at the University of California, Santa Barbara, have been gifted a solution.

Officials with the Innovative and Novel Computational Impact on Theory and Experiment, a Department of Energy program, have granted astrophysicists Matteo Cantiello and Yan-Fei Jiang 120 million CPU hours on the world's sixth-fastest computer. The researchers will get two years of access to the supercomputer Mira.

"Access to Mira means that we will be able to run calculations that otherwise would take about 150,000 years to run on our laptops," Cantiello said in a news release.

Unlike smaller one-dimensional stellar simulations, the model developed by Cantiello and Jiang will generate 3D simulations of the insides of massive stars, exploring the interactions of gas, radiation and magnetic fields. The researchers hope a better understanding of these interactions will yield insights into the nature of the episodic eruptions that bleed gas into space over the lifetime of a star.

The ways in which massive stars lose gas also have implications for the study of stellar structures created by supernovae, such as black holes and neutron stars. Scientists are hopeful revelations offered by their work with Mira will inform analysis of black hole systems like that one credited with producing the gravitational waves recorded by LIGO earlier this year.

640px-Mira_-_Blue_Gene_Q_at_Argonne_National_Laboratory_-_Skin"Understanding how these black hole binary systems formed in the first place requires a better understanding of the structure and mass loss of their stellar progenitors," said Jiang.

Mira is a pet scale Blue Gene/Q supercomputer. As of June 2013, it is listed on TOP500 as the fifth-fastest supercomputer in the world. It has a performance of 8.59 petaflops (LINPACK) and consumes 3.9 MW. The supercomputer was constructed by IBM for Argonne National Laboratory's Argonne Leadership Computing Facility with the support of the United States Department of Energy, and partially funded by the National Science Foundation.Mira will be used for scientific research, including studies in the fields of material science, climatology, seismology, and computational chemistry. The supercomputer is being utilized initially for sixteen projects, selected by the Department of Energy.

Interview: Helen Sedgwick, Author of ‘The Comet Seekers’

Ashampoo_Snap_2016.11.22_12h23m20s_002_In her novel The Comet Seekers, Helen Sedgwick presents an astounding narrative, which uses multiple points of views to weave a story that reaches across time and ultimately throws together two broken and lonely people in the middle of Antarctica. Sedgwick admits that The Comet Seekers didn’t initially start out as a full-fledged novel.  “I first had the idea for a story combining comets and history (back) in 2011, Sedgwick said. “I wrote it as a short story to begin with, but the characters kept calling me back for more.”

 Róisín and François are both running away from a past that haunts them, escaping feelings of guilt and regret. Róisín, an astronomer of Irish roots but with great ambition, and François who has lived all his life in a small northern French town has seldom left it, but finds solace and catharsis in cooking, encounter each other at a research base in Antarctica. Unbeknownst to each other they have shared a fascination for comets their entire lives and even as they develop a tentative closeness, Róisín and François are unaware that their paths are coincidentally joined by the lives and choices of their ancestors.

Sedgwick weaves multiple comet sightings and different points of view that begin in 2017 and trail back to the first glimpse of Halley’s Comet in 1066. But instead of finding it daunting, Sedgwick admits that it wasn’t as difficult as it seems. “I found the (different) points of view helpful in the writing process and in a way they directed the novel”, Sedgwick explained. “I knew that I wanted to write about people making different choices, and the multiple points of view allowed me to show why each of the characters make the decisions they do. It felt like the natural way to write a book about choice, and the ways in which we are both individual and connected.”

Ashampoo_Snap_2016.11.22_12h22m55s_001_But it’s not just the unique way how Sedgwick manoeuvres multiple POVs and navigates through different centuries. It’s that we see François and Róisín’s ancestors interact across time, living out their own fascinating and tragic stories. The groundwork is laid out for Róisín and François to meet in a way that almost seems preternaturally planned. Sedgwick however, doesn’t quite see it that way.

“I’d say the opposite (of preternaturally)”, she stated. “Their encounter was pure chance. Searching through history over a thousand years will show that we are all linked, and similar connections as those between Róisín and François can be found between all the people in our lives. It is not just that we are all related, though we are, but also that we all share something in common, and if we look for those similarities we will find them.” Indeed Sedgwick proposes an interesting theory. If in fact we are linked and bound together in a sort of “six degrees of separation”, is it then inevitable to repeat the history of our ancestors over and over again because it is engraved in our DNA?

In the opening scene of the novel, Róisín watches as a group of people run a marathon around the base that has temporarily become their home in Antarctica, while they await for the arrival of Comet Giacobini, the main reason they are there. Róisín  prefers to stand in the side-lines and observe, only joining the others as they run the final lamp in temperatures of minus ten degrees. It’s at that moment that she first encounters François, her first impression of him is that he seems so young but she is nevertheless intrigued by him.

Their first conversation takes place a while after the run, as they are drawn towards one another, even as Róisín is flooded with uncertainty about wanting his company:

❝One hour, forty minutes of darkness, and someone is behind her. Five days she has been here, five days she has searched the sky alone. Róisín turns around.

What are you looking for?

François is here, wanting to see what she’s doing, to join in. She’s not sure how she feels about that; she did not come here to make friends. Róisín thinks about telling him so, asking him to leave, but for some reason she decides to make him stay. Beside her, François looks at the sky and exhales.

There’s a comet predicted, she says. It’s going to be very bright. But it’s too early. I mean, we’re too soon.

Because it’s not dark enough yet?

Yes. Well, that and other things.

It’s beautiful isn’t it?

Above them, colours swirl like sea mist.

François stays where he is, doesn’t ask any more questions. He doesn’t take his eyes from the sky.

Róisín’s initial apprehension towards engaging with François in conversation may be better understood by observing her heart-breaking past. She lost not only the first man she ever loved but also the man she abandoned for her promising future as an astronomer, her cousin Liam. Róisín and Liam’s relationship, was complicated because of a perceived incestuous tinge and their completely different live paths. While Róisín moves to the city in her search for scientific developments in her field, Liam is dead-set on running his late father’s farm. This ultimately tears their relationship apart, and their breakup is later further tinted with tragedy.

Ashampoo_Snap_2016.11.22_12h28m00s_003_ Sedgwick writes her dialogues with no quotation marks, which initially can take some getting used to, even though she is by no means the first to do this. Cormac McCarthy, James Joyce, Jose Saramago, and Cynan Jones are only a few who have sought to abolish the conventionality of traditional punctuation seeking to challenge the reader, particularly in Jones’s case, to go beyond the well-known layout of how a dialogue is perceived.

Was Sedgwick afraid that readers would find this lack of speech marks intimidating? She says no. “I didn’t use speech marks because I enjoy the flow of prose without them, and I’m interested in the questions it raises about what we think and what we say, the internal and the external, she stated. “I must admit I didn’t worry about confusing the reader at all – I think readers are able to cope with pretty much anything, and I love them for it.”

Although Róisín is presented as a complex character whose life has been broken, François is no stranger to painful situations. Living with a mother who loves him dearly, but who is constantly plagued by the ghosts of her ancestors, François seeks solace in his ability to create recipes that help him imagine the many exotic places where he’s never been. Sedgwick admits that the character of François was for her the one that posed a complex task.  “Adult François was the most challenging character to write, because he had existed as a young boy in my mind for so long”, she said. “I (think) I had trouble getting him to grow up.”

As Róisín and François slowly come towards each other and begin telling their stories, Sedgwick’s astounding ability for description and engaging narrative through heart-felt dialogues between the characters really shines through. Róisín and François’s destiny is sketched not only by their individual actions and decisions, but also by those of their ancestors, who like them, were brought together by the magic and cosmic pull of comets. The Comet Seekers is a fascinating character and philosophical study that poses thought-provoking questions: Is our future decided solely by our actions? Or is our destiny somehow tied to those that came before us?

OSIRIS-REx Spacecraft Check Out and Early Cruise Phase Activities

cropped-av_orex_l2

It has been awhile since I posted anything to this site. The launch of OSIRIS-REx was such an amazing, emotional experience; it took me about a month to come back down to Earth (pun intended). I have now settled into a normal work routine in Tucson and the team has been busy operating the spacecraft and planning for the encounter with Bennu in 2018. We are now in the Outbound Cruise phase of the mission.

We Have a Healthy Spacecraft

Outbound Cruise began soon after the spacecraft separated from the Atlas V launch vehicle as planned. The spacecraft post-separation activities were all nominal and the spacecraft quickly transitioned to the “Outbound Cruise” operating mode. I studied the separation video quite a bit and noticed what appeared to be a plume originating from the lower portion of the spacecraft. After talking with the spacecraft engineers, we realized that the out-gassing was the result of the initialization of the propulsion system. This out-gassing was also evident in the DSN tracking data since we could see small forces slightly changing the spacecraft trajectory.

After launch-vehicle separation, the spacecraft was placed into the “Sun point” attitude (+X spacecraft axis toward the sun) with the solar arrays off-pointed from the sun by 45 degrees. This attitude ensures that the spacecraft will collect sufficient power to remain power positive at all times while keeping the other components from experiencing direct solar heating.

untitled3

Propulsion System Performance

The propulsion system has been performing well. Momentum dumps using the Attitude Control System (ACS) thrusters are occurring as planned. During these manoeuvres, reaction wheel momentum is unloaded by firing the ACS thrusters. Reaction wheels are flywheels that use electric motors to change their rotation speed. As the wheels rotate, the spacecraft counter-rotates as a result of the conservation of angular momentum.  Wheel speeds are generally maintained below 3000 RPM which requires desaturation of the built-up angular momentum approximately once every seven days.

We also executed our first Trajectory Correction Manoeuvre (TCM-1) using the TCM thrusters. This manoeuvre was placed into the mission plan to clean up any errors introduced by the Atlas V launch vehicle. However, since the Atlas V performance was nearly perfect, we re-designed TCM-1 as a minimal engineering burn, just to check out the TCM thruster performance. Our first major manoeuvre using the spacecraft main engines is Deep Space Manoeuvre #1 (DSM-1), which will be executed on December 28th, 2016. The preliminary design cycle for this manoeuvre has begun, with a DSM-1 Readiness Review planned for December 1st.

untitled2

Science Instrument Checkouts

As part of checking out the flight system, we turned on all of the science instruments and ran them through some basic functional check outs. I am happy to report that OCAMS, OVIRS, OTES, OLA, and REXIS all completed post-launch aliveness checkouts with no major issues.  OCAMS is investigating stray light effects which appear to be due to sunlight reflecting off PolyCam and OTES protruding from the +Z deck. We don’t expect this stray light to be an issue in operations but we are building a detailed optical model of the science deck and planning a follow-on characterization campaign later in Outbound Cruise. This model will allow us to maximize the science value of our imaging campaigns and ensure that stray light does not degrade our science data.

We also switched on the Touch and Go Camera System (TAGCAMS) and successfully acquired 19 images of star fields and spacecraft hardware. TAGCAMS is not part of the science payload; it is considered a component of the spacecraft Guidance, Navigation, and Control system. The purpose of TAGCAMS is to provide imagery during the mission to facilitate navigation to the target asteroid, acquisition of the asteroid sample and confirmation of asteroid sample stowage. The cameras were designed and built by Malin Space Science Systems (MSSS) based on requirements developed by Lockheed Martin and the OSIRIS-REx project.

untitled5

Near-term Activities

Right | The StowCam views the Sample Return Capsule in flight. This view will be critical as we stow the TAGSAM head with the collected Bennu sample for Earth return.

We still have many activities planned for Outbound Cruise. We will perform a thorough instrument calibration campaign at Launch + 6 months. We are busy planning for an extensive instrument check out and characterization during the Earth Gravity Assist in September 2017. We also have some tricks up our sleeves, with a science observing campaign planned for February 2017. Stay tuned for more details about this exciting activity in future blog posts.

Overall, the launch and early checkout of the OSIRIS-REx flight system has gone flawlessly. We have an amazing spacecraft and an extremely talented operations team. There is a lot of work to do to get ready for the encounter with Bennu in August 2018. However, we have the right equipment and the right team to get this job done successfully. With sample acquisition nominally scheduled for July 2020, OSIRIS-REx promises to be a highlight of planetary exploration over the next four years.

21 Nov 2016

Large number of dwarf galaxies discovered in the early universe

VST image of the Fornax Galaxy ClusterA team of researchers, led by University of California, Riverside astronomers, found for the first time a large population of distant dwarf galaxies that could reveal important details about a productive period of star formation in the universe billions of years ago.

The findings, just published in The Astrophysical Journal, build on a growing body of knowledge about dwarf galaxies, the smallest and dimmest galaxies in the universe. Though diminutive, they are incredibly important for understanding the history of the universe.

It is believed that dwarf galaxies played a significant role during the reionization era in transforming the early universe from being dark, neutral and opaque to one that is bright, ionized and transparent.

Despite their importance, distant dwarf galaxies remain elusive, because they are extremely faint and beyond the reach of even the best telescopes. This means that the current picture of the early universe is not complete.

However, there is a way around this limitation. As predicted by Einstein's general theory of relativity, a massive object such as a galaxy located along the line of sight to another distant object, can act as a natural lens, magnifying the light coming from that background source.

This phenomenon, known as gravitational lensing, causes the background object to appear brighter and larger. Therefore, these natural telescopes can allow us to discover unseen distant dwarf galaxies.

As a proof of concept, in 2014, the UC Riverside team, including Brian Siana, an assistant professor in UC Riverside's Department of Physics and Astronomy who is the principal investigator of the observing programs, targeted one cluster of galaxies that produce the gravitational lensing effect and got a glimpse of what appeared to be a large population of distant dwarf galaxies.

The just-published paper, whose lead author was Anahita Alavi, a post-doctoral scholar working with Siana, builds on that work.

The team used the Wide Field Camera 3 on the Hubble Space Telescope to take deep images of three clusters of galaxies. They found the large population of distant dwarf galaxies from when the universe was between two to six billion years old. This cosmic time is critical as it is the most productive time for star formation in the universe.

In addition, the team took advantage of the spectroscopic data from Multi-Object Spectrograph for Infrared Exploration (MOSFIRE) on the W.M. Keck Observatory, to confirm that the galaxies belonged to this important cosmic period.

These dwarf galaxies are 10 to 100 times fainter than galaxies that have been previously observed during these periods of time. Though faint, these galaxies are far more numerous than their brighter counterparts.

This study demonstrates that the number of these dwarf galaxies evolves during this important time period such that they are even more abundant at earlier times. Therefore, the researchers unveiled a population of dwarf galaxies that are the most numerous galaxies in the universe during these time periods.

Despite their faintness, these dwarf galaxies produce more than half of the ultraviolet light during this era. As ultraviolet radiation is produced by young hot stars, dwarf galaxies host a significant fraction of newly-formed stars at these cosmic times.

These results suggest that dwarf galaxies played a prominent role in the reionization era. These galaxies will be the primary targets of the next generation of telescopes, particularly the James Webb Space Telescope, scheduled to launch in October 2018.

New Horizons prepares for distant encounter beyond Pluto

Ashampoo_Snap_2016.11.21_11h44m33s_002_When we last visited with Alan Stern, principal investigator for NASA’s New Horizons, it was 2009, and the little probe was barely halfway to its planned encounter with Pluto. I asked him then, in the context of a terrible recession and assuming we got any images back at all, what taxpayers were getting for their money.

Paraphrasing, he replied rather presciently, ”Jobs for starters—and good, high tech ones at that. But more importantly: we are expanding human knowledge to the edge of our solar system. This is what great nations do, they make great history ... [Y]ears from now, when today’s politicians are forgotten ... a student or teacher who opens a textbook and sees Pluto will be looking at images and data from New Horizons. I think that’s worth a lot, because it is a legacy for our nation and our civilization.”

Since then, New Horizons delivered on every one of those predictions. The encounter was breath-taking, the incredible high resolution images of Pluto and its moons are exquisite, and the data will fuel several fields of study for a generation or more. So we caught up with a very busy Alan Stern, who took the time to get us caught up on where New Horizons is now, and more importantly, what it will do next.

Come below for some space exploration Q & A, and a free-ranging discussion in the comments.

DS: Before looking ahead, I wanted to ask, what has surprised you the most about the New Horizons mission overall, or any data it returned specifically?

AlanSternPlutophileAlan Stern: The public reaction. You know, we haven’t had a fly-by of a totally new planet and moon system since the late 80s and the Voyagers, since Voyager Two’s encounter with Neptune in 1989, so we expected some interest. We did not expect to get over one billion page views in a day or two! The team and I get something like 10 requests a week for presentations. Even a year-and-a-half a later, after encounter, people recognize me in airports and come up and shake my hand, kids send letters asking for autographs.

The one feature that surprised me the most? There are so many to choose from … maybe the heart-shaped plain now called Tombaugh Regio. Who could have possibly guessed that Pluto would have a heart the size of the American Midwest!

DS: New Horizons will make a pass by a classical Kuiper Belt Object or KBO dubbed MU69 beginning in late December 2018, with encounter set for Jan. 1, 2019. What can we learn from that relatively drab little snow-ball that we didn’t learn from big beautiful Pluto and its colourful moons?

MU69 as seen by HST attribution: NASA/SwRI/APLMU69 is barely visible to Hubble under extreme zoom, shown in circles as it moves over time. The background “snow” is random noise, the two brighter objects are faint stars.  Alan Stern: Well, it’s not just a drab little snowball. It’s between 25 and 50 kilometres across, orders of magnitude more massive than comet 67P that Rosetta just landed on, and we have no idea what it will look like. You remember how I told you years ago that when I was growing up and starting to study astronomy, there were four gas giants and four rocky terrestrial worlds, and that little Pluto was the lone oddball? And then we learned later on that there are at least half a dozen small planets like Pluto and probably hundreds if not more, meaning Pluto and its cohorts actually represents the most common kind of planet-sized object in the solar system?

Studying Pluto and its moons gave us a window into what that class of worlds might be like, it was a new class of planet seen close up for the very first time.

MU69 is whole new classes of objects seen close up for the first time, the Kuiper Belt Objects, the trans-Neptunian Objects. That alone is exciting.

But think about this: Up to now we could mostly see our planetary targets as disks before visiting them, in the case of Pluto a very small, very mysterious disk, but we knew a little bit about it before New Horizons. We knew it would be a sphere, we knew it would have a wisp of an atmosphere, we had a few hints on the colour and contrasts, that kind of thing. Now we can literally write the textbook on Pluto.

Ashampoo_Snap_2016.11.21_11h44m06s_001_Until we see MU69 close up, objects like it -- and there are billions of them! — they only show up as tiny specks of light in our most powerful telescopes. We know almost nothing about them at all. We believe these kinds of objects represent the basic building blocks for planets like Pluto and probably the rest of the planets as well, including possibly even Earth. And out there, where its so cold so far from the Sun, we believe they’re in the most pristine state. That they look like they did billions of years ago when the solar system was first forming. That can teach us a lot, we can't even guess how much until we see it and get data from it.

DS: Lastly, at the risk of being political, there are many people here and and around the world who would like to see more missions like this one. What can we do to convey that effectively to a new Congress and president?

Alan Stern: Tell your reps and your senators and the president that you support space exploration. Remind them how important space exploration is not just to science, but to developing other fields like engineering and technology, and even to national pride.

Remind politicians that a lot of today’s most successful entrepreneurs got hooked on science and technology as kids because of NASA. That’s what feeds innovation, and innovation is what feeds our economy. Tell our representatives and the new administration that you support more planetary exploration missions and all the other wonderful other things NASA does for our nation and our species.

Remember how much planning and preparation New Horizons took. If we started urging for and designing another mission like it, into far deep space, it might not launch for a decade. And it could take at least another decade or more to get out there beyond Pluto. So, it would be the 2030s before we got to see anything completely new. But if we wait too long to start, we might not be in that distant neighborhood again for the rest of this century!

The interview was conducted by phone and represents my notes and best recollection of what we discussed. Any remaining errors are solely mine — DS