AKARI first light

Back in February, the Japanese Space Agency (JAXA) launched the ASTRO-F mission, promptly renaming it AKARI (translates as "light"). The mission is a 0.7 metre infrared telescope that will survey the entire sky for warm objects such as dusty galaxies and dust/gas clouds where stars form. That will take a while, but some great 'first light' images have already been released.

Below are some images that AKARI took of the galaxy M81 at six different wavelengths of infrared light. Whilst the optical images of M81 generally show you where the stars are, the infrared tells you where the dust is. By studying galaxies such as M81 in the different colours of the electromagnetic spectrum, astronomers can try to work out what is going on in them.

Near- and mid-infrared images of the galaxy M81
Near- and mid-infrared images of the galaxy M81 observed by AKARI at wavelengths of 3, 4, 7, 11, 15, and 24 microns. CREDIT: JAXA/ISAS/LIRA

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Posted in astro blog by Stuart on Tuesday 30th May 2006 (17:21 UTC) | Permalink

The Lovell Telescope

I've just been looking though some of my photos from a few years ago so thought I would share one.

Lovell Telescope
The Lovell Telescope (September 2001) CREDIT: Stuart
This is a photo of the University of Manchester's Lovell Telescope. It's a radio telescope and is 76m across (equivalent to about three public swimming pool lengths). It was the largest radio telescope in the world when it was built in 1957. It had cost rather a lot of public money and was in financial difficulties before it was even finished. Although it was a University built science project, it turned out to be the only facility in the world that could track the carrier rockets that launched the Soviet Union's Sputnik satellite. Involving Britain with the start of the space race helped to save both it and the observatory and it's still going strong today. Look out for lots of 50th anniversary events happening next year.

Posted in astro blog by Stuart on Thursday 25th May 2006 (08:38 UTC) | Permalink

Stellarium 0.8.0

The latest version of the excellent (and free) Stellarium planetarium software is out. The software was originally developed by Fabien Chéreau but now has a whole team of excellent people involved. It is a great example of open source software at its best.

There are some nice improvements since 0.7.1 such as a night mode (everything goes red to preserve your night vision), constellation boundaries and a better world map to choose your location, although I notice that Manchester is missing for some reason. The search tool allows you to find all sorts of objects very easily and the whole interface looks a lot slicker. It is now possible to change the projection mode to include a spherical mirror which has made me worryingly happy. Not only does it have all the great features but it runs on Windows, Linux and Mac OSX.

So what are you waiting for - go download it now!

Posted in astro blog by Stuart on Wednesday 24th May 2006 (21:30 UTC) | Permalink

Space Junk Heritage

For almost fifty years we have been putting chunks of metal into orbit around the Earth. Many of these later come back down (or rather burn up in the atmosphere), but some still remain up in space. Most of these are tracked but the worry is that unknown objects are effectively like "an invisible mine waiting to impact on some other piece of space hardware" (quote from the Bad Astronomer) as they are travelling at a hefty speed. The general view amongst the space agencies is to think of ways to clear up some of this junk before it causes serious problems.

However, as an archaeologist from Flinders University (Ian's neck of the woods) points out, some items up there such as Vanguard One are actually representative of human space flight history. Dr Alice Gorman would like to see some classic satellites listed as World Heritage sites. An interesting thought as they certainly are important. My worry is how UNESCO would cope with broadening their portfolio beyond the surface of the Earth.

Posted in astro blog by Stuart on Wednesday 24th May 2006 (17:06 UTC) | Permalink

Mission to Mars

While having a bit of a late spring clean I stumbled across a 36 year old Brooke Bond picture card annual from 1970. The annual, The Race Into Space, was built up from picture cards that came with tea and covers the then recent space race. In fact it was published just before the cancellation of Apollo missions 18 and 19 and its optimism about the future of human spaceflight makes fascinating reading. It mentions the upcoming Skylab, the Viking spacecraft, a re-useable space shuttle, the Voyager missions (not by name) all of which have been and almost gone.

The annual also describes some programmes that have not (yet) been realised such as a 12-person space station, a lunar shuttle, Moon base and even a human trip to Mars. One plan that was described would have sent two spaceships to Mars in November 1981, each carrying six astronauts. These were to arrive in early August 1982 and orbit for 80 days before heading back to Earth via a swing-by of Venus. With hindsight this was an amazingly over-optimistic timescale as we are still at least 15 years off such a mission today.

Posted in astro blog by Stuart on Sunday 21st May 2006 (15:50 UTC) | Permalink

Three Neptune-mass planets

I've mentioned before that spectrographs can provide some amazing results despite the lack of pretty pictures. Now, a team of astronomers from France, Switzerland and Portugal have used the HARPS spectrograph on the European Southern Observatory's 3.6-m telescope at La Silla to find a solar system containing three Neptune mass planets. The planets orbit the star HD 69830. This star is slightly less massive than the Sun and is only (only!) about 41 light years away in the direction of the constellation Puppis.

The measurements don't directly observe the planets but actually infer their presence by watching how HD 69830 is slightly tugged around by them as they orbit. From the measurements, it was possible to say that the orbital periods - the time taken to orbit the star once - are 8.7, 31.6 and 197 days. Although we know about lots of planets outside the Solar System these days, this new system is notable because the planet with the longest orbital period is actually quite close to the region known as the habitable zone. This is the region where the temperature is between the melting point and boiling point of water and is the most condusive to life as we know it. Although that doesn't mean that this new planet has life on it, it is a step closer to finding Earth-like planets that might.

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Posted in astro blog by Stuart on Thursday 18th May 2006 (06:55 UTC) | Permalink

Aurora on Ch4

Although daytime TV isn't a likely place to find good astronomy, there was an excellent segment on the northern lights hidden away in The 100 Hottest Web Searches 2005 today. According to MSN search, the 68th most searched for phrase of 2005 (minus 'naughty' words and a few other things) was "Aurora Borealis". But rather than just relying on the standard celebrity 'talking heads' to discuss it, they actually let space scientist Dr Jim Wild have a couple of minutes to explain what causes the aurora. He used a nice animated diagram displayed on, appropriately, a plasma screen. He then showed us a magnetometer and even a couple of graphs from the Aurora Watch service (20,000 subscribers). Great science in a glossy '100 best' show. Fantastic!

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Posted in astro blog by Stuart on Tuesday 16th May 2006 (23:47 UTC) | Permalink

More podcasting news

Another UK-based astronomy podcast has hit the scene taking the total to three that I know of. The Astro London podcast is created by Kaustav Bhattacharya with additional help from Will Gater. The current episode (number 2) features an interview with Peter Grego, the Lunar section Director at the Society for Popular Astronomy. Sounds good!

The other two, in case you were wondering, are The Jodcast and the Thinktank Planetarium podcast.

Posted in astro blog by Stuart on Saturday 13th May 2006 (00:05 UTC) | Permalink

Naming stars

In my previous post I described how stars get their names and why most of them consist of strings of numbers and letters. Ultimately, there are just too many stars for it to be useful, or indeed practical, to give them all poetic sounding monikers.

However, some rather enterprising parts of humanity saw a gap in the market and they will name a star whatever you like, for a fee. For some reason snake-oil salesmen come to my mind. The important point to note here is that anybody could set themselves up as a business selling naming rights to stars. They could even sell names to stars that other people and companies have also named. There is no exclusivity and there is no authority other than that self-given. In the same way, anyone could start a business giving naming rights to species of animals (the Slacker Astronomy sloth anyone?) or naming countries (Australia could be Astrobloggerland).

Given these reasons then, why would someone pay good money to name a star? The star naming companies claim that they are selling a novelty gift that may get people interested in the night sky (scant evidence for that) and that their customers are aware of the fact that there is no recognition of the name other than by that company (are they?). At best this puts the product on the level of a "World's Best Dad certificate", but at worst it looks highly suspect. I am aware that some people pay to name stars after recently deceased relatives as a thoughtful gesture in their memory. These people are totally unaware that this trade is just an exercise in making fancy certificates and that puts people like me in an awkward situation. Do I tell them that the certificate has no meaning and was a waste of money, or do I protect their feelings at a difficult time and go along with it? This situation may be familiar to many astronomers, both professional and amateur, and the star naming companies do not have to deal with it. As a result, I do not like these companies and neither does the International Astronomical Union - the official international body that represents astronomers.

Having never bought a star name - I cannot bring myself to support these businesses in any way - I have never properly examined the 'product'. That is, until now. The other week my friend Peter told me that he had been bought a star - registered with the Intergalactic Star Database - as a bit of a joke. It turns out that a star naming pack can be bought in high street stores such as WHSmith for 'only' £29.99. Encouragingly, it does come with a copy of a Philips Star Chart and Planisphere. These useful tools (worth only around £10) are the only things in the pack. Despite my poor opinion of these certificates, I was still rather shocked by the poor, and frankly misleading, information provided. First let me show you the certificate:

Star Name Certificate
Naming certificate for The Proogs Star. CREDIT: Peter Scandrett
All very nice even if I could knock together something similar in around ten minutes. Looking a bit more closely at the certificate, I wondered if "Star Location: M6" meant the sixth Messier object. According to the explanatory document it is.

Star location
Document to show the location of the star CREDIT: Peter Scandrett
As you can see, the document give lots of information about M6 rather than the star that has been named. This is a bit sneaky of them, especially as the star (circled in red) looks more likely to be a member of the little clump of stars below it known as M7. After a bit of hunting with the excellent Aladin Java applet (Centre de Donnees astronomiques de Strasbourg), I reckon the circled star could be officially recognised HD 163519 - a magnitude 8.2 star - but it is a bit tricky to compare on my screen, so I could be wrong. Even so, you would need a telescope to see it.

Finally, the "Altitude" box has me completely confused. What are the hashed areas? What is the black hemisphere? Presumably the curved lines are supposed to indicate the elevations of two different stars over time to show where to look on May 6th. Why are there two sets of curved lines? From the UK, the maximum elevation of M6 (or M7) would be about six or seven degrees, so neither line represents the star in question. It just doesn't seem to make any sense.

Rather than waste £30 on something as silly as this, buy a copy of Norton's Star Atlas, Collins Pocket Guide to Stars and Planets or a Philips Star Chart. You'll save yourself some money and you'll get much more out of the night sky.

Many thanks to Peter for letting me pull apart his star certificate on this blog.

Posted in astro blog by Stuart on Friday 12th May 2006 (22:43 UTC) | Permalink

Star naming

Our galaxy contains about 100 thousand million stars. Of these, we can only see a few thousand with our own eyes and pretty much all of these visible stars have proper names that were given to them by Greek, Roman and Arab astronomers. Once the telescope was invented, it became obvious that there were many thousands of un-named stars out there and it was slightly impractical to give them all proper names. Not only was it difficult to come up with so many new names, but it was difficult to remember where a star was; imagine trying to memorise addresses for everyone in London by name. So, several systems or catalogues were devised to make it easier to find a particular star on the sky.

One approach was to assign a Greek letter to each star in a constellation starting with the brightest and adding the constellation name on the end. So, the brightest star in Centaurus was named Alpha Centauri and the third brightest star in Orion was Gamma Orion (proper name: Bellatrix). This system was created by Johann Bayer in 1603 and is still used today even though the ordering wasn't always right and some of the constellation designations are now incorrect.

Since Bayer's time other methods have been adopted and these, generally, tend to assign catalogue numbers to each star. These names usually come with an abbreviation for the particular catalogue before the number. So, Bellatrix is also known as

HD 35468 - the 35,468th star in the Henry Draper catalogue. That catalogue is organised in order of the Right ascension coordinate meaning that stars with a similar catalogue number won't be too far away from each other on the sky. That can be quite useful, as you can then tell where a star is roughly by its number. Some catalogues go even further in this regard by putting the star coordinates as part of the name. For example 1RXS J052507.7+062103 - a star in the 1st ROSAT X Survey - tells you the star has a Right ascension of 5 hrs, 25 mins, 7.7 secs and a declination of 6° 21' 3" even if it does look a bit unweildly.

The only drawback to catalogue names is that, over the years, many catalogues have been compiled for different research projects. As a result, many stars actually have several different catalogue numbers. For instance Bellatrix is also known as HIP 25336 (Hipparcos catalogue), IRC +10084 (Infrared catalogue) and SAO 112740 (Smithsonian Astrophysical Obs.) amongst others. Although having several names could be confusing, computer-based tools such as Simbad are great at finding the alternatives, so the situation isn't too bad.

The only down side to number-based names is that most people find memorising strings of numbers quite difficult. But, just as people used to remember telephone numbers of friends and relatives (that doesn't happen so much anymore with mobile phones), astronomers start to recognise their favourite objects by catalogue numbers too. Personally, for very large catalogues, I prefer names created from the star's coordinates as they are more useful. They also have less ambiguous pronunciations than names such as Betelgeuse or Zubenelgenubi.

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Posted in astro blog by Stuart on Thursday 11th May 2006 (23:07 UTC) | Permalink

All in the colours

Although astronomy is often seen to be about pretty pictures, one of the most exciting tools is spectroscopy. This is where you break down the light that you observe into its constituent colours. By identifying particular groups of colours, and the relative intensities of them, you can tell which elements or molecules are responsible. A familiar example is sodium which emits two specific shades of yellow and is the main component of 'orange' street-lights. So, by analysing the light you can tell the chemical composition of distant objects. This turns out to be a pretty amazing technique that can tell you all sorts about the physics of what happens in distant stars or galaxies.

Astronomers using the Ultraviolet and Visible Echelle Spectrograph (UVES) and the European Southern Observatory's Very Large Telescope (VLT), have used spectroscopic techniques to make very detailed measurements of a distant galaxy (redshift 4.224) by watching which colours it absorbs from the light of an even more distant quasar. This galaxy is observed at a time when the Universe was only about 1.5 billion years old i.e. less than 10% of its current age. The observation with the VLT comprised of five exposures which totalled over seven hours of time. With very detailed spectra, ratios of the various elements present within the galaxy could be calculated and this gives implications about its history. For instance, it was possible to deduce that lots of stars about 4-8 times the mass of the Sun must have reached the ends of their lives and dumped their nitrogen into interstellar space. That, in turn, means that there must have been a lot of star formation at least 200-500 million years previously. The observations also showed the presence of molecular hydrogen (H2) absorption lines, setting a record for the most distant object in which these have been measured. Apart from breaking records this is interesting because the measurements help to pin down the temperature of the gas (between 90 and 180 Kelvin) and are even able to suggest that for every two hydrogen atoms joined together as a molecule, there are about 250 hydrogen atoms sat by themselves.

It doesn't stop there though. Using observations of the light from a few more quasars, the authors reckon that the ratio of the masses of the proton and electron may have become 0.002% smaller in the last 12 billion years! If that turns out to be the case (much more evidence will be needed to confirm it) it is pretty exciting for our understanding of physics.

It is pretty neat to be able to work all these things just by looking at coloured light.

Posted in astro blog by Stuart on Tuesday 09th May 2006 (00:14 UTC) | Permalink

Unidentified Aerial Phenomena

Over the weekend there were a rush of newspaper stories about a Ministry of Defence report into Unidentified Aerial Phenomena. The report was created in 2000 and has just been released (to be published online on May 15th) after a request under the Freedom of Information Act by Dr David Clarke, a lecturer in the Department of Media Studies at Sheffield Hallam University. For the record, Dr Clarke is also a feature writer for the Fortean Times and has "an interest in supernatural belief and tradition... flying saucer cults and the UFO subculture".

The release was an opportunity for newspapers to say "UFOs officially exist", although most sources I read in the UK had pretty accurate headlines such as "Sorry ET, you're just a puff of plasma", " UFO study finds no sign of aliens" and "UFO sightings caused by freak weather". Frankly, I'm amazed that they stayed away from the easy, and misleading, first option.

It frustrates me that 'UFO' has two meanings; the actual meaning (there are things in the sky that people are unable to readily identify) and the popular meaning ("space aliens"). They aren't the same thing. Most scientists would agree that people can't always identify everything they see in the sky (UFOs), but that doesn't mean that they are alien spaceships. After all, there are the much more likely possibilities of birds, clouds, con-trails, aeroplanes, planets, meteors, ball-lightning, plasma and even fairies to eliminate before you get as far as life from another world. This is especially true when you consider that our current best guesses (the Drake Equation) at the number of communicating civilizations in our galaxy - from a handful to 10,000 - may be too optimistic.

Posted in astro blog by Stuart on Monday 08th May 2006 (18:16 UTC) | Permalink

Astronomy Day 2006

Today (6th May) is Astronomy Day - part of Astronomy Week. The aim of Astronomy Day is to "bring astronomy to the people," so there are many events organised to allow people who may never have looked through a telescope to see what all the excitement is about. Although the day is mainly based in the US, it has spread to several other countries. Check out the link for events taking place near you. However, the UK is not one of those involved in the project this year, so we'll just have to wait until 2009 for our next Astronomy Week.

Posted in astro blog by Stuart on Saturday 06th May 2006 (01:15 UTC) | Permalink

World Wind Add-on

I mentioned NASA World Wind in my previous post and said that it was possible to add data layers. I have been exploring the add-on possibilities and noticed that the Telescopes add-on doesn't seem to be available at the moment. So, I have started to put together my own Observatory add-on with individual icons for each observatory and links to home pages. Below is a screenshot of Europe to show what it looks like so far.

European Observatory Locations
NASA World Wind with my Observatories add-on data layer CREDIT: Stuart/NASA World Wind

Posted in astro blog by Stuart on Wednesday 03rd May 2006 (13:10 UTC) | Permalink

World Wind

If you've seen Google Earth in action, you have no doubt been impressed by what it offers; you can get a view of pretty much anywhere you like on the planet, using satellite imagery that Google has bought, with a very slick user interface. Although Google Earth is pretty nifty, I have never installed it myself. This was partly because of the license and partly because it wasn't easy to tinker about with it under the bonnet and I like to be able to do that. I haven't lost out though, because several months ago I found an Open Source alternative made by some nice folks at NASA. The program is called World Wind and it seems to be coming along quite nicely.

NASA World Wind
View of the Earth using Blue Marble maps and cloud data. CREDIT: Stuart/NASA World Wind
World Wind is created by scientists, so it has been given the capability to display all kinds of mapping data rather than just the standard satellite images. You can display the Blue Marble images, LandSat data, up-to-date cloud coverage, sea temperatures, information about floods, volcanic activity and a growing number of other data sets as people add to it. The inclusion of elevation data helps to give fairly recognisable views of your favourite mountain ranges when you zoom and tilt the view. Another cool feature in the latest version (which is reminiscent of Celestia) is the ability to swap the Earth for the Moon, Mars, Venus and even Jupiter. The Mars globe has height information - using the fantastic Mola data - so you can do neat things such as get a view down Valles Marineris or of Olympus Mons (although Rob has been doing some great Mars renderings too using Terragen). World Wind is now my favourite planet viewer.

Despite the groovy features, there are a few downsides to World Wind. Firstly, it is currently limited to Microsoft Windows 2000 and above. Hopefully somebody will help port the software to Linux and OSX to allow everyone to enjoy it. Secondly, the initial download is pretty huge, so you will need to have broadband. If neither of these is an issue for you, World Wind is a great bit of software that you could spend hours exploring with.

Posted in astro blog by Stuart on Wednesday 03rd May 2006 (00:57 UTC) | Permalink

Comet 73P/Schwassmann-Wachmann 3

Wow! Via Tom's blog I just had a look at a movie created from Hubble Space Telescope (HST) images of comet 73P. The movie is pretty spectacular and really does show the bits of the comet forming a trail as it breaks up. To have a look for the comet yourself, check out Ian's directions.

Posted in astro blog by Stuart on Tuesday 02nd May 2006 (15:58 UTC) | Permalink

Thinktank Planetarium

Last Friday I took a trip to Birmingham where I visited the Thinktank, Birmingham’s museum of science. Part of the reason for my trip was to see my friend Dave who is a planetarium presenter there. Thinktank is a huge, new building that contains an IMAX cinema, a department of a local university and several floors of interactive science exhibits covering Birmingham's industrial heritage, present day scientific issues in biology and technology and a look at what the future may hold for us. In the "thinkahead" section is the planetarium. It is totally digital, making use of an array of digital projectors to build up a full-dome image. I know that some people prefer the traditional Zeiss projectors, but digital projection does give you the flexibility to show so many different things including photographs, animations of the planets, 3D trips through space and full-dome video. A disadvantage of digital projection is that it makes it very easy to create 'canned' shows that just play back with a pre-recorded show. I'm glad to say that Thinktank is aware of the importance of presenter-led shows and seem to have the right combination of special effects and proper astronomy.

The show I saw was a run-through of the spring night-sky and started off in Birmingham with with cloud and street lights obscuring the view. Not only does this opening let see the limited view you get from a city due to light pollution, but it helps your eyes to adapt to the dark. After a tour through some of the planets, that you can currently see with the naked eye in the evening, we were then transported to a dark sky site. This was accompanied by "Wows!" from the children (and probably some of the adults) present as they suddenly could see thousands of stars. Dave described several constellation patterns before taking us on a trip away from the Earth into our local stellar neighbourhood. This trip drastically distorted the familiar constellation shapes and was a great illustration of the 3D nature of space.

After the show, Dave was able to show me some of the things that the DigiStar 3 can do. It is a truely impressive piece of kit that has a plethora of great features. It behaves like a souped-up combination of Stellarium and Celestia with movie and multi-wavelength capabilities. It was so cool to be surrounded by the Milky Way as it looks to a radio telescope at 408 MHz and switch to a gamma-ray view of the sky at the touch of a button. Thanks to Dave, I was treated to some of the fantastic shows that the Thinktank planetarium presenters are developing. I am now bright green with envy and wish I had my own planetarium to play about with.

Posted in astro blog by Stuart on Monday 01st May 2006 (19:08 UTC) | Permalink
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