30 Mar 2016

Radio Telescope facility damaged by attacker

On 29 March a  lone attacker drove a vehicle onto the Mauna Kea station of the Very Long Baseline Array (VLBA) Tuesday, damaging the installation's fence, building, and official vehicles. The attacker was apprehended by law-enforcement officers. The station's two employees were uninjured.

Initial reports indicate that the radio-telescope antenna is undamaged. Site personnel are assessing the damage to the building.

The VLBA is a continent-wide radio telescope system, with ten, 25-meter-diameter dish antennas. The Mauna Kea antenna is the westernmost, with one at St. Croix in the Caribbean, and eight on the U.S. mainland. The VLBA is operated from the National Radio Astronomy Observatory's Science Operations Center in Socorro, New Mexico.

The VLBA is used by astronomers around the world to make high-resolution images of celestial objects, and has made landmark contributions to our understanding of the Universe.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Contact:  Dave Finley, Public Information Officer
(575) 835-7302(575) 835-7302

28 Mar 2016

A galaxy in distress: M90, the most massive galaxy in the Virgo cluster

An international team led by researchers from the Laboratoire d'Astrophysique de Marseille (LAM) has used MegaCam on the Canada France Hawaii Telescope to observe NGC 4569 (M90).
RA:12h 36m 49.8s
Dec: +13° 09′ 46″
Mag: +9.5 
They observed, for the first time, spectacular tails of ionized gas that extend for over 300,000 light years, five times larger than NGC 4569 itself.
Click on the image to enlarge
Galaxies are not distributed uniformly throughout the universe. Some are found in dense clusters that can contain hundred to thousands of galaxies. Astrophysicists suspect that living in a cluster environment can have a strong influence in the way galaxies evolve. The tell-tail signs have long been recognized: for instance, compared to less dense regions, clusters contain proportionally more elliptical galaxies (spheroidal systems with little to no gas and dust) and fewer spirals (gas rich disky systems in which new stars are continuously formed from the gas in the interstellar medium). And even the few spiral galaxies found in clusters generally contain less gas and have an older population of stars than isolated spiral galaxies.

Several mechanisms have been proposed to explain the difference observed between galaxies in different environments. First, when two galaxies interact, tidal forces tend to rip apart and disrupt the outermost, less gravitationally bound and most diffuse parts. A second mechanism is the "dynamical pressure" exerted on the interstellar medium of a galaxy as it travels through the hot, diffuse medium that permeates the space in between galaxies, a process known as `ram pressure stripping’ (a biker travelling at high speed would experience a similar kind of pressure from the ambient air!). These two processes are able to lift gas from the disks of spiral galaxies, and therefore inhibit the formation of new stars. There is also a third mechanism that is thought to affect mostly the most massive galaxies: these galaxies host very massive black holes at their centres, and the energy liberated by the accretion onto these black holes, injected into the surrounding medium, can unbind the gas.
Identifying which of these processes is dominant is critical to constrain cosmological simulations that follow the evolution of galaxies. Observationally, however, observing the low density gas as it is being stripped is a tremendous challenge. The MegaCam Camera on the Canada France Hawaii Telescope (CFHT) has recently been equipped with a new, high efficient narrow-band filter that isolates the H-alpha emission line from the ionized gas, allowing it to be detected with high efficiency.
An international team led by researchers from the Laboratoire d'Astrophysique de Marseille (LAM) has used this instrument to observe NGC 4569, the most massive spiral galaxy in the Virgo cluster (at 45 million light years, the massive cluster of galaxies closest to the Milky Way). The Virgo cluster is still evolving, and therefore offers the opportunity to observe the transformation of galaxies as it takes place. NGC 4569 is moving through the cluster at a staggering 1200 km/s. The H-alpha image obtained with MegaCam at CFHT shows for the first time spectacular tails of ionized gas that extend for over 300,000 light years, five times larger than NGC 4569 itself ! This observation confirms that ram pressure stripping due to the intracluster medium is depriving NGC 4569 of its gas reservoir. An estimate of the mass of gas in these tails shows that 95% of the interstellar medium has already been removed from the disk of the galaxy, greatly limiting its ability to form new stars.
For a galaxy as massive as NGC 4569, it is perhaps surprising that internal gravitational forces are not strong enough to hold the gas together, counteracting the action of ram pressure stripping. Indeed, in cosmological models, it is hypothesised that in such massive galaxies, it is the activity related to the central supermassive black hole to cause the gas to be lost. The new observations show instead that the dominant effect is ram pressure: this important constraint must be taken into account in any cosmological model striving to incorporate the effect of environment on the evolution of galaxies.
The result also shows that MegaCam at CFHT is now a second-to-none world-class facility to study gas stripping and opens up a promising new avenue for understanding the role of environment in the evolution of galaxies.

23 Mar 2016

NEW IMAGE RELEASE of the 'WLM object' taken by ESO's VLT Survey Telescope

This scene, captured by ESO’s OmegaCAM on the VLT Survey Telescope, shows WLM which is so small and secluded that it may never have interacted with any other Local Group galaxy — or perhaps even any other galaxy in the history of the Universe.

Astronomers think that comparatively small primeval galaxies gravitationally interacted with each other and in many cases merged, building up into larger composite galaxies. Over billions of years, this merging process assembled the large spiral and elliptical galaxies that now appear to be common in the modern Universe. Galaxies congregating in this manner is similar to the way in which human populations have shifted over thousands of years and intermixed into larger settlements, eventually giving rise to today’s megacities.

This small galaxy features an extended halo of very dim red stars, which stretches out into the inky blackness of the surrounding space. This reddish hue is indicative of advanced stellar age. It is likely that the halo dates back to the original formation of the galaxy itself, helpfully offering clues about the mechanisms that spawned the very first galaxies.

The stars at the centre of WLM, meanwhile, appear younger and bluer in colour. In this image, pinkish clouds highlight areas where the intense light from young stars has ionised ambient hydrogen gas, making it glow in a characteristic shade of red.

This detailed image was captured by the OmegaCAM wide-field imager, a huge camera mounted on ESO’s VLT Survey Telescope (VST) in Chile — a 2.6-metre telescope exclusively designed to survey the night sky in visible light. OmegaCAM’s 32 CCD detectors create 256-megapixel images, offering a very detailed wide-field view of the Universe.

Maximilian Franz Joseph Cornelius Wolf (1863 -1932) was a German astronomer and a pioneer in the field of astrophotography. He was Chairman of Astronomy at the University of Heidelberg and director of the Heidelberg-Königstuhl State Observatory from 1902 until his death.

The Heidelberg State Observatory is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. While the new observatory complex was still under construction Max Wolf obtained a grant of $10,000 from the American philanthropist Catherine Wolfe Bruce for the acquisition of a powerful new dual 16 in refractor telescope, the Bruce double astrograph. For many years this telescope was the observatory's main research instrument.
Click on the images to enlarge

Wolf started his career as a comet hunter and continued to discover them throughout his life. He discovered or co-discovered several comets, including 14P/Wolf and 43P/Wolf-Harrington. He won a competition with E. E. Barnard on who would be the first to observe the return of Halley's Comet in April, 1910.

Along with E. E. Barnard, Wolf applied astrophotography to the observation of stars. The Bruce double-astrograph was originally designed to hunt dim asteroids but it was found to be ideally suited for the study of the proper motion of low luminosity stars using much the same technique.

In 1909 Max Wolf discovered the ‘Wolf-Lundmark-Melotte’ object or WLM for short. WLM has turned out to be one of the loneliest of galaxies that has had no interactions with its neighbours, and bears an uncanny resemblance to one of the two Magellanic Clouds which are satellite galaxies of our own Milky Way (galaxy).

It was identified as a galaxy in 1924 by astronomers Knut Lundmark and Philibert Jacques Melotte. The dim galaxy is located in the constellation of Cetus (The Sea Monster) about three million light-years away from the Milky Way, which is one of the three dominant spiral galaxies in the Local Group.

WLM is quite small and lacks structure, hence its classification as a dwarf irregular galaxy. WLM spans about 8000 light-years at its greatest extent, a measurement that includes a halo of extremely old stars discovered in 1996.

In 1919 Max Wolf published a catalogue of the locations of over one thousand stars along with their measured proper motion. These stars are still commonly identified by his name and catalogue number today. Max Wolf died on 3 October 1932.

First discovery of a binary companion for a 1a type supernovae

Ia SUPERNOVEA are used as standard candles to measure the distances of nearby galaxies, however, the are known to fall into different classes so there are problems with using this method.
A team of astronomers including Harvard's Robert Kirshner and Peter Challis has detected a flash of light from the companion to an exploding star. This is the first time astronomers have witnessed the impact of an exploding star on its neighbour. It provides the best evidence on the type of binary star system that leads to Type Ia supernovae. This study reveals the circumstances for the violent death of some white dwarf stars and provides deeper understanding for their use as tools to trace the history of the expansion of the universe. These types of stellar explosions enabled the discovery of dark energy, the universe's accelerating expansion that is one of the top problems in science today. The subject of how Type Ia supernovae arise has long been a topic of debate among astronomers.
"We think that Type Ia supernovae come from exploding white dwarfs with a binary companion," said Howie Marion of The University of Texas at Austin (UT Austin), the study's lead author. "The theory goes back 50 years or so, but there hasn't been any concrete evidence for a companion star before now."
Astronomers have battled over competing ideas, debating whether the companion was a normal star or another white dwarf.
"This is the first time a normal Type Ia has been associated with a binary companion star," said team member and professor of astronomy J. Craig Wheeler (UT Austin). "This is a big deal."
The binary star progenitor theory for Type Ia supernovae starts with a burnt-out star called a white dwarf. Mass must be added to that white dwarf to trigger its explosion - mass that the dwarf pulls off of a companion star. When the influx of mass reaches the point that the dwarf is hot enough and dense enough to ignite the carbon and oxygen in its interior, a thermonuclear reaction starts that causes the dwarf to explode as a Type Ia supernova.
For a long time, the leading theory was that the companion was an old red giant star that swelled up and lost matter to the dwarf, but recent observations have virtually ruled out that notion. No red giant is seen. The new work presents evidence that the star providing the mass is still burning hydrogen at its Center, that is, that this companion star is still in the prime of life.
According to team member Robert P. Kirshner of the Harvard-Smithsonian Center for Astrophysics, "If a white dwarf explodes next to an ordinary star, you ought to see a pulse of blue light that results from heating that companion. That's what theorists predicted and that's what we saw.
"Supernova 2012cg is the smoking—actually glowing—gun: some Type Ia supernovae come from white dwarfs doing a do-si-do with ordinary stars."
Located 50 million light-years away in the constellation Virgo, Supernova 2012cg was discovered on May 17, 2012 by the Lick Observatory Supernova Search. Marion's team began studying it the next day with the telescopes of the Harvard-Smithsonian Center for Astrophysics.
"It's important to get very early observations," Marion said, "because the interaction with the companion occurs very soon after the explosion."
The team continued to observe the supernova's brightening for several weeks using many different telescopes, including the 1.2-meter telescope at Fred Lawrence Whipple Observatory and its KeplerCam instrument, the Swift gamma-ray space telescope, the Hobby-Eberly Telescope at McDonald Observatory, and about half a dozen others.
"This is a global enterprise," Wheeler said. Team members hail from about a dozen U.S. universities, as well as institutions in Chile, Hungary, Denmark, and Japan.
What the team found was evidence in the characteristics of the light from the supernova that indicated it could be caused by a binary companion. Specifically, they found an excess of blue light coming from the explosion. This excess matches with the widely accepted models created by U.C. Berkeley astronomer Dan Kasen for what astronomers expect to see when a star explodes in a binary system.
"The supernova is blowing up next to a companion star, and the explosion impacts the companion star," Wheeler explained. "The side of that companion star that's hit gets hot and bright. The excess blue light is coming from the side of the companion star that gets heated up."
Combined with the models, the observations indicate that the binary companion star has a minimum mass of six suns.
"This is an interpretation that is consistent with the data," said team member Jeffrey Silverman, stressing that it is not concrete proof of the exact size of the companion, like would come from a photograph of the binary star system.

Silverman is a postdoctoral researcher at UT Austin.
Only a few other Type Ia supernovae have been observed as early as this one, Marion said, but they have not shown an excess of blue light. More examples are needed.
"We need to study a hundred events like this and then we'll be able to know what the statistics are," Wheeler said.
The work is published today in The Astrophysical Journal.

20 Mar 2016

Gravitational Waves

Running time: 45m

Acknowledgements: Andrew Wilson, John McConnell., and the National Science Foundation (US).

In this month’s program the topic is gravitational waves. We take a look at LIGO and how it works, along with the historic discovery of gravitational waves in September 2015. We consider the cause of gravitational waves, black holes, supernovae, and what the future holds for gravitational wave astronomy. Finally we look at the European Space Agency’s LISA Pathfinder mission which begins its science observations this month (March 2016).

18 Mar 2016

Are you ready for the Transit of Mercury?

A few days ago I was having a chat with my friend Pranvera Hyseni in Kosovo. She and her outreach team are doing such great work in the townships in the country as part of the Charlie Bates Solar Astronomy Project, by giving local people the opportunity to view the Sun safely through  telescopes and safety glasses.
         Pranvera was saying just how much she and her team were looking forward to the next Transit of Mercury that will take place on 9 May 2016, and how excited she and her team were to see the planet Mercury pass across the face of the Sun during the course of the afternoon.
               This transit will be seen by observers in much of eastern S. America, E. America, Canada, Europe and NE. Africa.        

The very first Transit of Mercury was seen in Europe 389 years ago, and its place in history is assured. It occurred on the 7th of November, 1631. In a dissertation published at Leipsic, Germany, in 1629, Johannes Kepler notified to astronomers that according to his calculations a transit must occur on this day, since at the time of conjunction he had found the latitude of Mercury by his tables less than the Sun's semi-diameter. This interesting prediction was verified by Gassendi, at Paris. He discovered the planet on the disc of the Sun shortly before nine o'clock in the morning. At first he thought it was a sunspot which had not been re­marked on the preceding day, but continuing his observations, its motion was soon detected, and he saw the planet leave the Sun's disc on the western limb about 10.30 am. It was found that Kepler's tables represented the circumstances with far greater precision than even the author himself had hoped for.
The second observation of a transit of Mercury was made by Jeremiah Shakerley.  Shakerley was the son of William Shakerley of North Owram, Halifax, in England. On the morning of the 3d of Novem­ber, 1651, at Surat, in the East Indies. It is said Shakerley was so desirous of witnessing the phenomenon that, having found by his calculations it would be invisible in England, he made the voyage to India for the purpose.
The third recorded transit was observed at Dantzic by the celebrated astronomer, Hevelius, on the 3d of May, 1661. He saw the planet on the Sun's disc for 4½ hours.
The next transit took place on the 7th of November, 1677, and was witnessed by Edmund Halley, at St. Helena, and by M. Gallet, at Avignon. Halley thought the times of ingress and egress might be observed within a single second of time, and pointed out how the Sun's parallax might be ascertained from such observations, taken at places widely distant from one another, remarking, however, that the difference of the par­allaxes would not be large enough to give very certain results.
A transit of Mercury occurred on November 10, 1690, and was observed in China by the Jesuit missionaries, at Erfurt by Oodfrey Kirch, and at Nuremberg by Wurzelbaur. Another in 1697, on November 3, was witnessed by astronomers at Paris, and other places. One on the ninth of November, 1723, when watched at Paris, Genoa, Bologna and Padua, but the first complete European observation of a transit of Mercury bears the date November 11, 1736, when nearly all the astronomers of the time observed the planet in its progress across the Sun. The transit of 1802, November 9, was seen by the well-known Jerome de Lalande, who was the more interested in it, inasmuch as he remarks it was the last he could hope to witness. That of 1832, May 5, was visible in the UK, though a general prevalence of unfavourable weather occasioned much disappointment. The next occurred on the 7th of November, 1835, but was not visible in Europe. Another on 1845, May 8, was partially observed in the UK, and also that of, November 8, 1848, which is the 25th that has occurred since the phenomenon was first noted by Gassendi.
Pranvera Hyseni has good reason to be 'excited, by the next Transit of Mercury, since she will be following in the footsteps of such great astronomers as Hevelius, Johannes Kepler and Sir Isaac Newton on this great occasion. The rest of us amateur astronomers should be just as excited, and looking forward to this very special event. After this Transit you will have to wait until 20 November 2019 for the next to occur, so please make a note in your diary.
Richard Pearson

16 Mar 2016

Build your own Extremely Large Telescope

Dutch astronomer Frans Snik has designed a model of ESO’s European Extremely Large Telescope (E-ELT) using LEGO® components. Following on from the success of that design (more than ten models have been built by enthusiastic individuals worldwide since it was published), Snik has now dedicated some of his spare time to designing a LEGO® model of one of the Unit Telescopes that make up ESO’s Very Large Telescope (VLT).
For almost 20 years now, the VLT has been amazing astronomers with its extraordinary capabilities. One of the largest telescope facilities in the world, the VLT consists of four independent telescopes that can be operated together to make a very powerful facility. Now ESO is building its big brother, the ELT, that will extend our reach even further into the heavens. You may not be able to build your own full-size versions of these telescopes, but the models are a convincing, and much more practical, substitute — and they are an excellent way to understand how complex modern astronomical instruments work.


Snik used the design tools ldraw and bricksmith to build his new model of the VLT, as he did for the E-ELT model. The VLT requires exactly 3104 parts, all of which can — with some care and attention — be ordered from various LEGO® providers through bricklink. The scale of the model is approximately 1:150, just the same as the E-ELT model, and the total cost of the parts is about 500–550 euros, depending on which instruments are included. The model comprises the telescope and the entire dome structure, and all of the instruments used on the real VLT can be built. It rotates and all the dome shutters and vents open and close.
Not only can you use Snik’s design plans to build your own versions of these two iconic telescopes, but you can now vote for them to be produced and sold by LEGO® as complete kits by visiting the LEGO® Ideas website. Keen LEGO®-builders with an interest in astronomy will surely want to vote for these models. Once 10 000 votes are received for a design, LEGO® undertake to consider it for production as a kit.
For now, anyone wanting to build their own version of either (or both!) of these huge telescopes can download the detailed construction manuals (for the VLT, and for the E-ELT) and lists of bricks needed (for the VLT, and for the E-ELT). Even expert builders will need to invest some time to build one of the biggest telescopes in the world as it takes at least a few days to order the parts and piece each model together. But the final product will certainly make the effort worthwhile!
The first VLT model built by Snik was donated to ESO’s Director General Tim de Zeeuw, to stand in his office alongside the earlier model of the E-ELT. Both the LEGO® VLT and the E-ELT will be on display in the forthcoming ESO Supernova Planetarium & Visitor Centre at the ESO Headquarters in Garching, Germany from 2017.

Ground based observations confirm Ceres is still 'an active world'

HOW TIMES FLY, it does not seem all that long ago since the NASA spacecraft DAWN arrived at Ceres, yet the first anniversary of its arrived passed on 6 March 2016. Since then DAWN has settled into its science orbit 233 miles above the asteroid and has send back some amazing images.

At 760 miles in size Ceres is the largest member of the minor planets that orbit around the Sun midway between the planets Mars and Jupiter.

It turns out that Ceres far more dynamically active than the asteroid Vesta, which DAWN first visited in November 2011.

Astronomers from Italy, Germany and Chile, made a series of observations of Ceres in July 2015, in which they measured the radial velocity of some of the surface features. The observations confirmed that plumes volatile gases were being pumped into space from the location the main white spot in the crater named Occator.

The Team of astronomer led by Paolo Molaro, at the INAF–Trieste Astronomical Observatory, and Antonino Lanza, at the INAF–Catania Astrophysical Observatory, have been using the European Southern Observatories 3.6-metre telescope at La Silla observatory situated in the southern part of the Atacama desert of Chile.

Attached to the ESO 3.6-metre telescope is the HARPS spectrograph that is normally used in the search for extra solar planets to detect minute wobbles in a stars’ motion. HARPS picks up small changes in the star’s radial velocity along the line of sight.

Observations made using the HARPS spectrograph have revealed unexpected changes in the bright spots on the dwarf planet Ceres. Although Ceres appears as little more than a point of light from the Earth, very careful study of its light shows not only the changes expected as Ceres rotates, but also that the spots brighten during the day and also show other variations. These observations suggest that the material of the spots is volatile and evaporates in the warm glow of sunlight.

The volatiles are being released every time that the white spots enter direct sunlight during its 9 hour rotation period.

The recent Dawn observations suggest that the bright spots could provide some atmosphere in this particular region of Ceres confirming previous water vapour detection. It has been noted that the spots appear bright at dawn on Ceres while they seem to fade by dusk.

That could mean that sunlight plays an important role, for instance by heating up ice just beneath the surface and causing it to blast of some kind of plume or other feature.  
The lead author of the new study, Paolo Molaro, at the INAF–Trieste Astronomical Observatory, takes up the story: "As soon as the Dawn spacecraft revealed the mysterious bright spots on the surface of Ceres, I immediately thought of the possible measurable effects from Earth. As Ceres rotates the spots approach the Earth and then recedes again, this affects the spectrum of the reflected sunlight arriving at Earth.”

Ceres spins every nine hours and calculations showed that the effects due to the motion of the spots towards and away from the Earth caused by this rotation would be very small, of order 20 kilometres per hour. But this motion is big enough to be measurable via the Doppler Effect with high-precision instruments such as HARPS.

The team observed Ceres with HARPS for a little over two nights in July and August 2015. "The result was a surprise," adds Antonino Lanza, at the INAF–Catania Astrophysical Observatory and co-author of the study. "We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night.”

The team concluded that the observed changes could be due to the presence of volatile substances that evaporate under the action of solar radiation. When the spots inside the Occator crater are on the side illuminated by the Sun they form plumes that reflect sunlight very effectively. These plumes then evaporate quickly, lose reflectivity and produce the observed changes. This effect, however, changes from night to night, giving rise to additional random patterns, on both short and longer timescales.

If this interpretation is confirmed Ceres would seem to be very different from Vesta and the other main belt asteroids. Despite being relatively isolated, it seems to be internally active. Ceres is known to be rich in water, but it is unclear whether this is related to the bright spots. The energy source that drives this continual leakage of material from the surface is also unknown.

Dawn is continuing to study Ceres and the behaviour of its mysterious spots. Observations from the ground with HARPS and other facilities will be able to continue even after the end of the space mission.

15 Mar 2016

Is there life in the universe?

IS THERE LIFE IN THE COSMOS? This is a question that I get asked a lot by viewers. I believe the answer is a resounding 'Yes.'  This photo from the European Southern Observatory is one of my favorites. It shows 2 telescope that search for extra solar planets against the lovely band of the Milky Way. There are billions of stars in our galaxy alone, and a mind boggling number that make up all the galaxies in the universe. Today over 3000 alien planets have been discovered along with protoplanetary disks of new solar systems in formation. The chances of there being life out there is pretty good, and this image sums up that interpretation nicely. It was released by ESO today.

This picture was taken just before dawn at the La Silla Observatory, in outskirts of the Chilean Atacama Desert. A layer of orange hovering over the horizon announces the imminent arrival of the Sun. These first hints of daylight are kissed by the Milky Way, which stretches out across the entire night sky. This view of our home galaxy is covered with dark patches, formed from dust particles blocking the light behind them.

In front of this cosmic scenery you can see some of the observatory’s telescopes. The closest is the Swedish–ESO Submillimetre Telescope (SEST), whose dish measures 15 metres across. It was decommissioned in 2003 and replaced by the Atacama Pathfinder EXperiment telescope (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA). On the plateau in the background stands the ESO 3.6-metre telescope, with the Coudé Auxiliary Telescope (CAT) right behind it.

SEST seems to be pointing at an extremely bright object: This is Venus, one of our neighbouring planets. Venus is lit up by the Sun and outshines all of the stars in the night sky. The triangular white glow that reaches up from the horizon through Venus is called zodiacal light. Zodiacal light is sunlight scattered by dust in the ecliptic — the plane of Earth’s orbit around the Sun.

Richard Pearson

Credit: ESO/B. Tafreshi (twanight.org)

14 Mar 2016

Searching for Extra Solar Planets

In the Atacama Desert of southern Chile is the European Space Agency’s 3.6-metre telescope.

 The telescope hosts HARPS, the High Accuracy Radial velocity Planet Searcher, the world's foremost exoplanet hunter. HARPS is a spectrograph with unrivalled precision and is the most successful finder of low-mass exoplanets to date.

 Attached to the ESO 3.6-metre telescope, HARPS searches nightly, and with unparalleled accuracy, for exoplanets. Today it leads the field, regularly generating astounding results that will present fresh challenges for future telescopes like the E-ELT.

What does HARPS really do to detect these planets? It is all matter of perspective. As we are so far from the stars, we cannot see their exoplanets directly. Instead HARPS detects minute wobbles in the stars’ motion. Stars and their exoplanets are bound together by gravity, so an exoplanet orbits its distant parent star, just as the planets of the Solar System orbit the Sun. But a planet in orbit around a star exerts its own gentle pull, so that the orbital centre of the system is a little away from the centre of the star and the star itself orbits about this point — which we can detect as a small regular movement of the star to and fro along our line of sight. This tug of war between any star and its exoplanets can be seen (or rather, measured) by HARPS, with an incredible precision. HARPS picks up small changes in the star’s radial velocity (i.e. along the line of sight), which can be as little as a gentle walking pace of 3.5 km/hour

Due to the Doppler effect, this radial velocity change induces a shift of the star’s spectrum towards longer wavelengths as it moves away (called a redshift) and a shift towards shorter wavelengths (blueshift) as it approaches. This tiny shift in the star’s spectral lines can be measured with a high-precision spectrograph such as HARPS and used to infer the presence of a planet.
Astronomers who used the telescope in July 2015 have now made a new significant discovery .... !

13 Mar 2016

Five Greatest imiges of the Solar System

SUNDAY 13 March
BBC4 at 10pm GMT.

As the presenter of Astronomy & Space over the last 3 years I have been privileged to see a great many images returned by spacecraft, and I have made programs about the most striking missions to the planets so far. 

I am waiting to see the team's choice of  images, for me the images of Pluto beamed back by New Horizons last autumn were both historic and impressive, and planetary scientists will learn a great deal from studying these for years to come.
As a personal choice the next images I would chose are those of comet 67P/Churyumov–Gerasimenko beamed back by ESA's Rosetta spacecraft since November 2014. Never before have we seen a comet in such fine detail, and had great science data returned to waiting astronomers. These images have improved our understanding of what comets are, there composition, and their origin. As it turns out comet 67P/Churyumov–Gerasimenko is the same age as the solar nebulae out of which our planets were formed 4.5 billion years ago, and there is water in its surface.
My third choice are the magnificent images of Mars beamed back by visiting spacecraft, including ESA's Mars Global Surveyor, which also returned a great deal of science from Martian orbit showing regions of Water, Magnetism, and Mass concentrations around the red planet. I shall have more to say about this in my new program.
My forth choice would have to be images of the Sun transmitted back to Earth from NASA's Stereo mission, which has allowed us to study the Sun on all sides in unprecedented detail, and NASA's SOHO mission, which has allowed space scientists to study the Sun every few minutes, every day for the last 20 years. I should add that SOHO is responsible for the discovery of 3,000 comets. 
My 5th and final choice would be the recent images of Ceres sent back by NASA's Dawn spacecraft since July 2015. Ceres is the largest of the Minor planets orbiting between Mars & Jupiter, and the one with the 2 mysteries white spots that has intrigued planetary scientists in recent months, and we are still unsure of what they are composed of. Dawn also previously returned magnificent images, and science data, from the asteroid Vesta, showing a huge impact crater caused by a planetesimal impacting Vesta a billion years ago. 
As amateur astronomers you get to see amazing images of the Sun & planets as you log onto Face Book most days; I am sure that you are also spoilt for choice: What great images would you chose & why? I will look out for your own personal choices in the days ahead.
Best wishes & Clear Skies
Richard Pearson

12 Mar 2016

The Europen Mission to Mars Ready for Launch

ESA's ExoMars spacecraft is now sitting on top of the Russian rocket waiting to launch at 09:30 GMT on a journey to the red planet Mars. There are high expectations for the mission following the amazing success of the Rosetta probe and its Lander Philae following there arrival at comet 67P/Churyumov–Gerasimenko in November 2014.
 While the primary objective is to study the Martian atmosphere, its probe Schiaparelli is designed to descend down on the Martian surface. This is an ESA landing demonstrator to help prove the reliability of landing a rover on Mars at a later date. There is NO rover on board Schiaparelli; therefore the search for life during this mission is very restricted.
I shall watching the launch from 08:30 GMT live, and I am a little anxious as not all rocket launches are 100% reliable.
The primary landing site for Schiaparelli  has been identified: it is a plain known as Meridiani Planum. This area interests scientists because it contains an ancient layer of hematite, an iron oxide that, on Earth, almost always forms in an environment containing liquid water. If all goes well Schiaparelli will perform localised experiments for up to 3 Sols (Martian days).
Mars is a fascinating world, if simple microbial life can be found there, it will mean life can evolve where it can, and it will improve our chances of finding life elsewhere in our solar system. It will also show that we are not alone in the Universe, and life will have evolved on distant planets given the right conditions.
Richard Pearson

    3 Mar 2016

    ESA: ExoMars spacecraft prepares for launch

    Please join me on 30 March., my new program of 'A.S' will be looking in detail at what we know about the planet Mars to date along with the ExoMars mission which is taking along a Mars Lander to study the red planet.
    The ExoMars 2016 spacecraft - consisting of the Trace Gas Orbiter (TGO) and the Schiaparelli entry, descent and landing demonstrator - is in Baikonur, Kazakhstan, preparing for its mid-March launch on a Russian Proton rocket. This joint European and Russian mission will test key exploration technologies and search for evidence of methane and other rare gases in the martian atmosphere.
    These gases could result from geological processes or they could be signatures of current biological activity on the planet. Three days before reaching Mars in October, Schiaparelli will separate from the orbiter and coast towards the planet in hibernation mode to reduce power consumption.
    The film covers the journey, the orbit of the Trace Gas Orbiter, the separation of the Schiaparelli lander and its 20 000 km/hour descent and eventual landing. It also contains filming at ESA’s European Space and Technology Centre (ESTEC) Mars Yard in the Netherlands. Learning more about Mars’ water and environment will shed further light on this planet - while knowing the origin of its methane could finally answer the exciting question of whether there is life on Mars.

    2 Mar 2016

    This is Mars

    The views from spacecraft have shown geological features that have changed little over the past 1 billion years, some of which are indicators that water once flowed on Mars, and that the planet is volcanically active. Please click on the images for a closer view.

    1 Mar 2016

    The Aerial Telescope of Robert Hooke

    Robert Hook (28 July 1635 – 3 March 1703)
    Robert Hooke was born at Freshwater, Isle of Wight, son of John Hooke, curate at All Saints' Church. The church stands at the end of what is now Hooke Road, which also has the Hooke Museum. Robert Hooke was one of the most brilliant and versatile of seventeenth-century English scientists, but he is also one of the lesser known; his persona and his contributions are far outweighed in public perception by those of Newton and of Wren. This is unfair.

    Please click on the image to enlarge

    He was a scientist who made valuable contributions with his splendid illustrations of insects, and made astronomical observations. He was also a British architect who assisted in redesigning London after the great fire of 1666.

    He constructed his own aerial telescope which he used to observe the star Gamma Draconis, which is of unusual design.

    In 1669 he lodged at Gresham College, London, where he carried out astronomical observations with an aerial telescope of his own design. On 15 July 1669 the then Astronomer Royal John Flamsteed informed the Royal Society he was observing in Gresham college the parallax of the earth’s orb, and hoped to give a good account of it. The Astronomer Royal later described to Isaac Newton how Hook ‘by ingenious means fixed the objective lens of his telescope tube, 36 feet in length, in the roof of his chamber, in order to observe the distances of the stars from the vertex. The measurements Hook passed to Flamsteed covered precisely the period of the summer recess of 1669.

    After a few months. Hooke observed a displacement in the expected position of Gamma Draconis, but he tells us that unfortunately the objective lens of his telescope accidentally broke and he therefore discontinued his observations.

    In 1725, four years after his Oxford appointment, James Bradley began a research programme with Samuel Molyneux (1689-1728), a brilliant amateur telescope maker. Molyneux had been impressed by the efforts of Robert Hooke, who, unwilling to let any new idea pass him by, had in 1669 made a series of measurements of the star Gamma Draconis that appeared straight overhead from London. By observing a star at so high an altitude, Hooke hoped he would be able to reduce the effects of the Earth's atmosphere on the accuracy of his measurements. In this his reasoning was sound, for when a star is observed overhead, the light from it passes through a thinner layer of air than when it lies close to the horizon, and so is less disturbed by air currents and by distortions due to the air itself. With an overhead star the measurements he made of its position with reference to other stars would have every likelihood of being far more accurate than those made at any other angle, and since he noticed a shift in position he thought that what he measured might well be parallax.

    James Bradley became the third Astronomer Royal at the Royal Greenwich Observatory, and popularised the theory of the aberration of starlight.

    The English astronomers James Bradley (1693-1762) and Samuel Molyneux (1689-1728) repeated Hooke's observations in 1725 with a better telescope and discovered that the observed displacements could not be due to parallax, but they were unable to interpret them. By 1727, however, after erecting another telescope and continuing his observations, Bradley found the explanation as due to the finite velocity of light, which the Danish astronomer Ole Romer (1644-1710) had determined in 1676.

    Bradley thus was able to establish the motion of the Earth, finally accomplishing Hooke's Attempt to Prove the Motion of the Earth from Observations.