It may seem too early to be thinking about it, but across the world eclipse chasers are getting ready for the best eclipse of the 21st century which takes place on July 22nd next year. With total solar eclipses like this one, it’s all about the length of totality and – if you’re in the right place – this one lasts more than six minutes. Getting to the right place is the challenge, and for this eclipse the place to be is in the middle of the sea, just south of Japan.
I’m going to be on board the Superstar Libra which will be on a specially organised eclipse cruise. If you’d like to join me, Terry Pratchett and a whole host of other amateur astronomers on board, I’d suggesting booking your tickets as soon as possible via Eclipse of the Century.
I’ve really missed podcasting since the demise of Living Space’s previous incarnation, and the odd interview just isn’t the same. I’m delighted to say that I’ve managed to cajole the very busy and very knowledgeable Douglas Pierce-Price from ESO, the European Southern Observatory to join me. You can listen to our first show here :
or download it by right clicking here. We’ll have a web site up to go with this shortly, but in the meantime here’s this episode’s show notes.
In today’s show, Chris and Douglas talked about the how the planet Mars has turned out to be colder than expected, how the youngest supernova remnant in our Galaxy has just been discovered, and how astronomers have used a distant quasar and galaxy to take the temperature of the early Universe.
NASA’s Mars Reconnaissance Orbiter finds that Mars is colder than previously thought
Observations made with the Shallow Radar instrument (SHARAD) on the Mars Reconnaissance Orbiter (MRO) have shown that the outer shell of Mars is colder and more rigid that previously thought. SHARAD, which was built for the spacecraft by the Italian Space Agency, uses shallow subsurface radar to search for liquid or frozen water to a depth of about a kilometre in Mars’ crust. By looking through the layer of ice, sand and dust in the Martian north polar cap, the researchers could see through to the surface of the rocky crust underneath. It turns out that the planet’s surface is not sagging under the weight of the icy polar cap (as would happen on Earth), meaning that Mars’ outer shell must be very thick and cold. This result has implications for the search for liquid water hidden beneath the surface (and therefore also possible sites for life on Mars), as any underground aquifers would have to be deeper than previously thought in order for temperatures to be high enough.
Youngest Supernova Remnant in our Galaxy discovered
When a massive enough star reaches the end of its life, it can explode as a supernova. Theoretical models suggest that roughly two or three supernovae should happen in our Galaxy every century, but astronomers do not see as many as they would expect. The most recent observation of a supernova in our Galaxy was in 1604, of what is known as “Kepler’s Supernova”, and the youngest known “supernova remnant” – the shell of expanding material following the explosion – had until recently been Cassiopeia A. Observations of Cassiopeia A suggest that its parent supernova would have been observed on the Earth around 1680, but there are no definite historical records of it. Now, astronomers have found a supernova remnant in our Galaxy which has been caught at the new record youngest age of 140 years. The object, called G1.9+0.3, was first identified as a supernova remnant in 1985 by astronomers led by Dave Green from the University of Cambridge, using the Very Large Array (VLA) radio telescope in New Mexico. Then, in 2007, a team led by Stephen Reynolds of North Carolina State University observed the same object with the Chandra X-ray Observatory, and found that it was 16% larger than in 1985. The shell must be expanding very quickly to have grown so much in 22 years, which tells us that it must be very young. Follow-up observations at the VLA confirmed this result, and by looking at the expansion rate the astronomers were able to calculate the record-breaking age of the young supernova remnant. The supernova itself could not have been seen 140 years ago because of obscuring dust towards the centre of the Galaxy, but thanks to radio and X-ray observatories which can penetrate the dust, today’s team were able to find this example of the “missing population” of young supernova remnants.
Using a quasar and a galaxy to take the temperature of the early Universe
Astronomers have used a distant galaxy, and an even more distant quasar, to take the temperature of the early Universe. For the first time, they were able to detect a tell-tale absorption of light by carbon monoxide (CO) molecules in a galaxy so far away that its light has taken 11 billion years to reach us. The observations, made with ESO’s Very Large Telescope (VLT) in Chile, used the light from an even more distant quasar – a galaxy which emits intense radiation powered by a black hole in its core – as a ‘flashlight’ to study the galaxies between the quasar and the Earth. When the quasar’s light passes through each intervening galaxy, molecules in the galaxies absorb specific wavelengths of that light. Due to the expansion of the Universe and of the light itself over these billions of years, each galaxy leaves a fingerprint in the quasar’s light at different wavelengths. In this particular very distant galaxy, the astronomers observed the fingerprint of CO molecules, where the precise levels of absorption depend on their temperature, so the molecules act like a cosmic ‘thermometer’. Today, the Universe is filled with Cosmic Microwave Background radiation at a temperature of 2.725 K (about -270 Celsius). However, according to the Big Bang theory, the Universe was hotter in the past. The theory predicts that the temperature 11 billion years ago would be about 9.3 Kelvin, and the observations of the CO molecules gave a temperature of 9.15 Kelvin, plus or minus 0.7. This is an excellent match with theory, and an exciting new result which shows how interstellar chemistry in the early Universe can be used to tackle big cosmological questions.
Following my post over the weekend about the dangers of satellite building, here’s JPL’s excellent video about the Phoenix landing.
For those of you who’ll be online watching and waiting for Phoenix’s safe landing, I hope you’ll be able to join Doug Ellison (from Unmanned Spaceflight) and myself along with other experts for the ride; watch this space for stream details.
It’s exam season in Oxford, and I’ve made my first sightings of scared looking undergraduates in formal academic dress heading for the exam schools. I’m used, at this time of year, to waking up in the middle of the night tormented by dreams of the years that I sat through exam after exam after exam. This year’s been different, though, and instead of quantum mechanics and question choices I’ve been dreaming nervous dreams of landing ellipses and ice beneath the Martian surface.
In just over a week, if all goes well the latest probe to the red planet will touch down near the Martian poles and begin its study of the area. For many if not most of the science team preparing for the ride of their lives, this is a second shot at Mars as most were involved in the ill-fated Mars Polar Lander mission; that’s why the mission is called Phoenix, after the mythological bird that rises from its own ashes.
Landing at or near the poles, rather than at the safer equatorial region, brings a whole set of new challenges. The angle of entry into the atmosphere must be different, and Phoenix’s seven minute descent is a minute or so longer than that taken by Spirit and Opportunity, for example. Phoenix is too large and will be travelling too quickly to use airbags, and so will have to attempt a soft landing on what Mars Reconnaissance Orbiter, living up to the second word in its name, has revealed to be in parts rocky and even bouldered terrain.
I feel attached to Phoenix because of an amazing day I spent with the team behind her in Tucson a year or so ago. If the thought of those seven minutes of fear is keeping me awake, what must it be doing to the team who’ve been working on MPL and Phoenix for a decade or more?
Mars has a reputation for being an awkward planet to land on, and the overall success rate – especially when you compare it to that for Venus, which should be a much harder prospect – is surprisingly low. In the UK, I don’t think anyone who followed the story of Beagle 2 will ever forget it. Beagle 2 was an amazingly audacious project, attached to ESA’s Mars Express (which has, it shouldn’t be forgotten, been a wonderful success) designed to jump over several steps in NASA’s ‘follow the water’ strategy for Mars. While Phoenix is part of a series of missions designed to identify the possibility of life on Mars, find the best locations and then finally test there, the good ship Beagle tried to scoop the prize first time.
You know the punch line, I imagine, but there is good news. Many of the instruments and innovation that went on and into Beagle are being incorporated into Exomars, the European rover scheduled for launch in 2013. Exomars looks rather like its American cousins, Spirit and Opportunity, with six wheels and a tall mast with cameras on it, but it will carry a different set of instruments being less of a robot geologist and more of a robot astrobiologist.
I’ve been following the Exomars project for at least a couple of years now, and – apart from being scared – that’s the other reason I’ve avoided a career involving strapping lovingly built instruments on top of rockets. The Hubble Space Telescope was first conceived in the late 1970s and launched in 1990, for example. On both sides of the Atlantic planetary scientists are attempting to decide whether the next mission to the outer Solar System will go to Jupiter and the icy oceans of Europa, or to Saturn for Titan’s methane rain and the fountains of Enceledus. Despite the huge efforts being undertaken, I’ve spoken to no one who believes the mission will launch in less than 15 years.
Devoting half of your research life to a project and then having to watch, helpless, as it launches and then plummets through the Martian atmosphere? I’d almost rather be back in my 3rd year quantum physics exam. Almost….
I promise a post about NASA’s announcement will follow when I have some time and am awake. In the meantime, I’m getting lots of emails about this story; a robot conducting an orchestra is being billed as a great breakthrough.
Except the robot isn’t conducting the orchestra. It’s copied a series of movements from someone who knew what they were doing, and has no ability to react to the sound being produced. Given worlds enough and time (two things I’m short of, right now) I could learn to copy a decent conductor, so please could somebody explain why this is impressive.
I promise a post about NASA’s announcement will follow when I have some time and am awake. In the meantime, I’m getting lots of emails about this story; a robot conducting an orchestra is being billed as a great breakthrough.
Except the robot isn’t conducting the orchestra. It’s copied a series of movements from someone who knew what they were doing, and has no ability to react to the sound being produced. Given worlds enough and time (two things I’m short of, right now) I could learn to copy a decent conductor, so please could somebody explain why this is impressive.
At 6pm UK time today, NASA are announcing what they bill as “the discovery of an object in our Galaxy astronomers have been hunting for more than 50 years. This finding was made by combining data from NASA’s Chandra X-ray Observatory with ground-based observations.” I’ll be blogging the press conference live…
Update: I’ve been running late all day. You can find the answer on Phil’s blog here and I’ll post my thoughts later. Sorry.
I wanted to share this snippet from Sebastian Faulkes’ Engleby, a novel set in the Cambridge of the 1970s.
Heisenberg and Bohr and Einstein strike me as being like gifted retriever dogs. Off they go, not just for an afternoon, but for ten years; they come back exhausted and triumphant and drop at your feet … A vole. It’s a remarkable thing in its way, a vole – intricate, beautiful really, marvellous. But does it … Does it help? Does it move the matter on?
When you ask a question that you’d actually like to know the answer to – what was there before the Big Bang, for instance, or what lies beyond the expanding universe, why does life have this inbuilt absurdity, this non sequitur of death – they say that your question can’t be answered, because the terms in which you’ve put it are logically unsound. What you must do, you see, is ask vole questions. Vole is – as we have agreed – the answer; so it follows that your questions must therefore all be vole-related.
Powerful stuff, and I suspect many of the people who ask questions after my cosmology talks go away feeling short changed by their helping of vole. I suppose I can only say that we try as hard as possible to get what we can from the Universe; and if it only gives us voles then, to mix metaphors horribly, we have no choice but to make vole-ade and ask voley questions.
