Archive for the 'Hubble Space Telescope' Category

SM4: peering over the shoulders of giants

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With the Space Shuttle Atlantis (STS-125) and her crew now waiting for the right conditions to come home and land after repairing and upgrading Hubble, I thought now would be a good time to look back at what has happened over the past ten days or so. Servicing Mission 4, to Hubble, has been nothing short of spectacular – with risky spacewalks, dramatic repairs and a real sense of cutting edge space exploration. Spaceflight author Andrew Chaikin has recently blogged on why he felt “amazed, inspired–and grateful” watching the Hubble Servicing Mission unfold, and it’s really worth reading his thoughts here. This mission has been especially exciting and indeed has been different – both in terms of the added public interest and in how the community of space and astronomy enthusiasts has followed along.

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To me this has been largely, if not wholly, because of the constant stream of images, tweets, blogs and live video streams that NASA has been sending out on a frequent basis. With video cameras in the astronauts’ helmets we’ve been able to literally peer over their shoulders and watch live what they were doing up there on Hubble. This really hit home to me, a couple of days ago, when I saw a video that was filmed in the cockpit of the Shuttle Atlantis, as the astronauts parted ways with Hubble. The video gives a real sense of what it’s like to be working on the deck of the Shuttle and, as Phil says, there’s something about the clear audio which greatly adds to this. It’s a must see. Stuart has the story of the video here.

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For my part I’ll be remembering and reliving the exploits of this incredible mission through the many pictures taken by the astronauts. I’ve put a few of my favourites in this post, but there are hundreds out there. Click on the images, in the post, to get the NASA high res. versions. And why not let me know what your favourites are in the comments below, or on my Twitter feed.

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All images courtesy NASA.

Hiding Ganymede and an extrasolar connection

jupiterhubble1Jupiter & Ganymede. Credit: NASA, ESA, and E. Karkoschka (Univ. of Arizona)

Jupiter might not exactly be well placed for observing from the Northern Hemisphere this year, due to its relatively low altitude, but all is not lost. NASA have just released this beautiful, “close to natural” colour, image from the Hubble Space Telescope. It shows the Galilean moon Ganymede beginning to disappear behind the southwestern part of Jupiter’s enormous disc. You can watch a video of Ganymede disappearing behind Jupiter (over the course of two hours) on the NASA Hubble site. The images were taken in April 2007 and, as can be seen in the crop of the main image below, they show the huge rocky and icy moon in quite some detail.

ganymedehubbleGanymede disappearing. Credit: NASA, ESA, and E. Karkoschka (Univ. of Arizona)

Compare this new Hubble image of Ganymede to the one (below) from the New Horizons mission en-route to Pluto and you get a feel for just how good Hubble’s resolution is! The bright splodge towards the upper middle of Ganymede’s terminator in the New Horizons image is a huge crater known as Tros and it’s clearly visible, as a bright white spot, in Hubble’s shot as well. There are features smaller than Tros visible in the Hubble image too. That’s not to say that the New Horizons image isn’t any good. Far from it, it’s amazing — it’s just that Hubble is one impressive instrument!

newhorizonsganymedeA view of Ganymede from the New Horizons spacecraft as it whisked by.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Anyway I’m moving a little away from my point. Not only is Hubble’s new shot a wonderful picture, full of intriguing details on both Jupiter and Ganymede (especially the high resolution versions), it also illustrates nicely how astronomers have been able to study Jupiter’s atmosphere. The method astronomers have been using to do this is also similar to how astronomers ‘probe’ the atmospheres of distant exoplanets. Ganymede is reflecting light from the Sun back towards us (that’s how we can see it). That light passes through the upper reaches of Jupiter’s atmosphere, towards us, as Ganymede disappears behind the limb of the huge planet. By spectroscopically studying the chemical fingerprints stamped on this light, by Jupiter’s atmosphere, astronomers can then work out important properties and compositions of the gases in this part of the Jovian atmosphere.

exoplanetlimbAn illustration showing light passing through the atmosphere of an exoplanet.
Credit: ESA, NASA and Frederic Pont (Geneva University Observatory)

In a very similar way, when studying exoplanets, astronomers have been able to detect the chemical signatures of interesting molecules in exoplanetary atmospheres, that have been stamped on the light from the exoplanet’s parent star. So it isn’t just in studying the gas giants of our own Solar System that this versatile astronomical technique is used. It will be interesting to see what these observations from Hubble tell us about Jupiter’s atmosphere. If they are anything like the results seen from studying the atmospheres of distant exoplanets, they will be very interesting indeed.

Hubble, Keck and Gemini directly image distant exoplanets

An artist’s impression of Formalhalt b orbiting its parent star.
Credit: ESA, NASA and L. Calçada (ESO)

In two separate papers published in the journal Science today, astronomers announced that they have directly imaged several extrasolar planets around other stars. One team used Hubble to find an approximately 3 Jupiter mass planet orbiting the star Formalhalt, whilst another team used Keck and the Gemini telescopes to find a family of planets around the star HR8799. Hubble studied Formalhalt in visible light and was able to make what can only be described as a truly remarkable image (see below), of the planet embedded within the star’s dusty disc. I think Stuart’s suggestion for its name is spot on.

The view of Formalhalt (masked by a coronagraph) showing the new planet embedded within a dusty disc (inset). See the annotated full-resolution image here.
Credit: NASA, ESA and P. Kalas (University of California, Berkeley, USA)

These discoveries clearly mark an important waypoint in our efforts to image an Earth like planet around a distant star, but they are also absolutely amazing in their own right. There’s far more in-depth commentary out there in the blogosphere, so I’ll point you in the direction of Sarah Askew, Phil Plait, Dave Mosher (who has a great IM interview with an exoplanet expert) and of course there’s an episode of the Hubblecast that you can watch below!

Hubble videos

For any of you reading the blog who came to my Hubble talk last night, hello! As promised here are a few select links to some of the videos from the presentation. First up is a zoom into the Hubble Ultra Deep Field.

Next is a pair of videos showing the creation of the stunning Cat’s Eye nebula – first the companion star dies creating the concentric shells of material, then the jets and magnetic field of the other (alive) star warp and twist into the nebula to create the central detail and swirls. The first part is here and the second you’ll find by clicking here.

Lastly then is a video of the bizarre object called V838 Monocerotis. You can download the video by clicking here. And remember that you can see more videos and (almost) all of the images from my talk on the ESA Hubble website here – www.spacetelescope.org.

Final Hubble talk for 2008

On Monday (13th October) I will be giving my final Hubble talk of the year to the West of London Astronomical Society (WOLAS). It will be, once again, entitled “Not just pretty pictures – the science behind Hubble’s greatest images”. The society has written a nice synopsis of the background of the talk, on their meetings page here.


What are these (different) things coming out of this cloud? Come to my lecture to find out! Credit: NASA and Jeff Hester (Arizona State University)

I’ve really enjoyed giving this particular talk this year however I’m going to be busy working on something else for the next few months, so this will be my last one for a bit. For now though if you are interested in coming along to the WOLAS meet-up here’s a map to Christ Church, Redford Way, Uxbridge where the meeting is being held.

Super sharp Hubble shows stars in nearby galaxies

The Hubble Space Telescope is renowned for its incredible resolution used in studying the depths of the Universe – from the earliest galaxies to some of the grandest spirals. Recently though it has been using these superb capabilities to observe nearby galaxies – that is, a selection of galaxies between about 7 and 13 million light years from the Earth.

Above: Hubble’s resolution has revealed NGC 253 as a swirl of countless stars and dust lanes, enabling new insights into the character and structure of this beautiful galaxy.

At this time of year I love to get out a wide-field refracting telescope and use it to spot the relatively bright galaxies M31 (the Andromeda Galaxy) and M33. Through the eyepiece they appear as bright smudges of light, M31 being slightly elongated in shape. Those smudges are in fact the accumulated light of billions of stars shining away brightly, inside their respective galaxies. Yet we can’t see the individual stars in the galaxy with our amateur telescopes because their resolving power is simply too low, they appear blurred and merged together. But with Hubble things are much different.

When it looked at 69 nearby galaxies, its powerful optics were able to show individual stars and glittering star clusters within them. This ability to look at the fine detail has allowed astronomers to make important studies into the lives of these stars, how they are born and more. Astronomers can then also use the observations to make detailed conclusions about the shape and structure of the (often intricate) galaxy they are studying.

We can liken some of the previous observations to trying to understand how the population of a city lives, interacts and moves around, just by looking at a street-map. With Hubble’s brilliant resolution astronomers have been able to get a far more detailed view of the lives of galaxies and their stars – we can study the people in the street as it were. As Benjamin Williams, of the University of Washington says in the ESA press release “With these images, we can see what makes each galaxy unique”.

Left: A maelstrom of thousands upon thousands of individual stars reveals itself in this Hubble Advanced Camera for Surveys image of NGC 300, some 7 million light years away from Earth.

These observations are important because it is essential for astronomers to build an understanding of galaxies close to the Milky Way, in order to investigate (and hopefully understand) those which might be subtly different in the farther, or even extremely distant Universe. How are stars forming and how fast? Where are the old stars and why are some galaxies so massive? These are all questions which studies like these look to answer. Thankfully the survey which Hubble was working on (the ANGST or ACS Nearby Galaxy Survey Treasury) is wide ranging and shows a diverse sample of galaxies. It aims to create a practically complete study of all the galaxies in what is known as the Local Neighbourhood. So slowly but surely we are getting to know our cosmic neighbours!

Meanwhile, with the Hubble Servicing Mission 4 postponed until further notice (due to an anomaly with Hubble’s control unit) we are going to have to sit back and wait patiently to see if, and when, Hubble can get back to doing its usual spectacular science.

Image credits – Top; NASA, ESA, J. Dalcanton and B. Williams (University of Washington), T.A. Rector/University of Alaska Anchorage, T. Abbott and NOAO/AURA/NSF: Left hand side; NASA, ESA, J. Dalcanton and B. Williams (University of Washington)

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