And there's more...

Wow. It would appear that not one, but two large objects have been found way out beyond Pluto and have been announced in the last day or so.

The first is 2003 EL61 which has a mass of about 32% that of Pluto. If it has a similar density to Pluto, it would have a diameter of around 1500 km. See more here, here, here and here. 2003 EL61 even has its own moon which orbits every 49 days (five observations gave a precise orbit). It would appear that 2003 EL61 was first seen by some astronomers (see below) at Caltech but the first announcement was by astronomers at Instituto de Astrofisica de Andalucia.

The second object is 2003 UB313 (temporary name) is being called the 10th planet as it seems to be a bit larger than Pluto. It was found by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory in Hawaii and David Rabinowitz of Yale University. They have already submitted a name to the International Astronomical Union (IAU). The page title would suggest it was Lila (perhaps after Mike Brown's daughter) but that is just a guess and wild rumour on my part.
Update: Mike Brown now states that he got sentimental when writing his webpage early in the morning.

Posted in astro blog by Stuart on Saturday 30th Jul 2005 (01:55 UTC) | Permalink

A leap second

According to ABC Science, a leap second will be added to clocks around the world at midnight on the 31st December. That means that the last minute of 2005 will contain 61 seconds rather than 60. The last time this happened was in 1998/1999.

These days a whole lot of professions - not just astronomers - rely on accurate timing and many make use of an international network of atomic clocks. Atomic clocks monitor the oscillations of ceasium atoms and are more reliable than other man-made clocks. The only trouble is that they gradually go out of sync with the day as measured by the position of the Sun. That isn't because they aren't accurate enough, but is actually due to the Earth changing its rate of rotation.

The rotation rate changes when anything happens to the distribution of matter on/in the planet. An example would be the recent tsunami which caused a large region of the Earth's crust to sink ever so slightly. When part of a rotating object moves inwards it causes the whole thing to speed up - this is called conservation of angular momentum. Admittedly, this is a tiny effect but it can gradually add up.

The International Earth Rotation Service (IERS), takes a decision every six month as to whether an extra second is required to keep Coordinated Universal Time (UTC) in line with GMT. If a leap seconds is needed it gets added to the end of June or December accordingly. One side effect is that the radio pips, heard every hour on some BBC radio stations, will gain an extra 'pip' for midnight on 31st December 2005.

Posted in astro blog by Stuart on Wednesday 27th Jul 2005 (15:52 UTC) | Permalink

Not long to go

There is only about half an hour to go until the Space Shuttle finally gets re-launched. The hatch has been closed and launch should occur at 15:39 BST as long as nothing else goes wrong. Fingers crossed.

Posted in astro blog by Stuart on Tuesday 26th Jul 2005 (14:11 UTC) | Permalink

Going to Mars

After reading Tom's post about Mars Reconnaissance Orbiter, I thought I would list some of the planned missions to the red planet plus some of those under consideration. It will give the Earth a chance to gain back some points on the Mars Expensive Hardware Lob scorecard (we are currently losing 17 points to 20).



  • Mars Reconnaissance Orbiter (NASA)
    Arrives: November 2006
    Location: 190 miles altitude orbit
    Objectives: Higher resolution images of the surface, sub-surface radar.


  • Rosetta (ESA)
    Arrives: February 2007
    Location: Mars flyby on way to Comet 67P/Churyumov-Gerasimenko
    Objectives: No Martian observations announced yet


  • Phoenix (NASA)
    Arrives: May 2008
    Location: On the surface between latitude 65 and 75-north
    Objectives: Take images during descent, stereo images on the surface, dig trenches up to half a metre into the water ice, analyze soil samples with an oven and observe the martian atmosphere.


  • Mars Telecommunications Orbiter (NASA)
    Arrives: September 2010
    Location: In orbit at a distance of 5000 km
    Objectives: Act as an interplanetary communications hub using near infrared lasers to communicate with Earth. It will also release a football-sized (soccer ball) lump of metal which it will attempt to track in orbit as a test for a future sample-return mission (possibly 2013).


  • Mars Science Laboratory (NASA)
    Arrives: October 2010
    Location: TBD
    Objectives: Test precision landing techniques, analyze martian soil for organic compounds, detect water, observe the weather, X-Ray Spectrometry.


  • ExoMars (ESA)
    Arrives: TBD
    Location: In orbit and on the surface (two spacecraft)
    Objectives: characterise the biological environment, a rover equipped with a drilling system and a sampling and handling device.


  • Mars Sample and Return (ESA and or NASA)
    Arrives: TBD (> 2011)
    Location: In orbit and on the surface (five spacecraft in ESA design)
    Objectives: Land on Mars, collect samples and return them to Earth.


  • Astrobiology Field Laboratory (NASA)
    Arrives: TBD
    Location: Surface
    Objectives: Look for evidence of life past or present.


  • Deep-drill Lander (NASA)
    Arrives: TBD
    Location: TBD
    Objectives: Drill hundreds of metres into the Martian surface.

Posted in astro blog by Stuart on Tuesday 26th Jul 2005 (01:22 UTC) | Permalink

Train travel

I write this as I sit on a train going up the west coast mainline (posted when I got home of course). When I got on the train, at Watford Junction, I found that my seat reservation put me at a table with three other people up to Stafford. Some people don't like being sat next to others but I don't mind it. After a while, the friendly, mature lady next to me asked me where I was going and what I did. I said that I studied astronomy and all three were instantly interested. I love the fact that astronomy quite often gets that reaction from people.

All three of them were travelling together and were really great, with a fantastic fascination for science of all kinds. I had loads of fun talking with them all on the way up to Stafford covering everything from cosmology to string theory to genetics. They really were very interested, knew their stuff and were excited by science. I love people like that. I wish I always sat next to that type of person.

If you happen to be one of the people I met, I mentioned a couple of great websites during our conversation. I'll give them here just in case you forgot:

Also, any links to the right should lead to interesting places.

Finally, apologies to those sat nearby that wanted peace and quiet - I'm sorry but I just get excited by this stuff.

Posted in astro blog by Stuart on Sunday 24th Jul 2005 (21:37 UTC) | Permalink

October Eclipse

Here is an advance warning of an annular solar eclipse that will be visible on 3rd October. Unfortunately for some, it is only visible from Europe and Africa. The best places - those that see the greatest eclipse - are northern Portugal, Spain (Madrid at 08:56 UT), Algeria (Algiers at 09:05 UT), Tunisia, Libya, Chad, Sudan (10:31 UT), Ethiopia, Kenya and Somalia (11:30 UT). If you live near those countries (for various definitions of near) you should be able to see a partial annular eclipse. In Manchester we should have around 65% of the maximum eclipse. If you live further south you will see more, and further north you will see a bit less. Something to look out for on your way to work.

I'll leave you with a picture of an annular eclipse that I took from the top of a Scottish mountain, at sunrise, back in 2003. It was fantastic!

Annular eclipse seen from Scotland in 2003

Posted in astro blog by Stuart on Thursday 21st Jul 2005 (23:30 UTC) | Permalink

Google Moon

You may have heard of Google Earth; a nice Google atlas of the planet. In honour of the 36th anniversary of the Apollo 11 landings, Google has made a lunar version. Just be careful that you don't zoom in too far otherwise you might just see what the Moon is really made from.

Posted in astro blog by Stuart on Thursday 21st Jul 2005 (00:01 UTC) | Permalink

Dust devils

With all the excitement over Cassini and Deep Impact, I was in danger of forgetting some of our other solar system explorers. On Spirit's 501st Martian day (31st May), its navigation camera took some home movies of Martian dust devils. Rather cleverly, the folks at JPL and Texas A&M have enhanced the contrast of just the bits of the image that vary between frames. That way, the little whirlwinds appear much more obvious than they would have done otherwise. Clicking on the animation takes you to NASA's full sized version (6 MB).

Martian dust devils
IMAGE: NASA/JPL/Texas A&M

Posted in astro blog by Stuart on Tuesday 19th Jul 2005 (00:09 UTC) | Permalink

Shenzhou VI

China has set the date for its second manned rocket launch, Shenzhou VI. The rocket will launch in early October and will carry two astronauts into a low Earth orbit. They will orbit for five to six days. This will be significantly longer than the 21 and a half hour journey of Yang Liwei, China's first astronaut, two years ago.

Posted in astro blog by Stuart on Saturday 16th Jul 2005 (21:19 UTC) | Permalink

What a night

OK, this is vaguely Harry Potter related but don't run away just yet. The Harry Potter/Astronomy night has finished and seemed to go very well. Overall, around 150 people turned up to look through telescopes, see stars in an inflatable planetarium, have an outside lecture about the Universe, a 3D trip to Mars (polarised glasses), make a whole lot of stuff like 3D glasses (to look at 3D images taken by the Mars rovers) and, oh yeah, get the Harry Potter book. The 42ft radio telescope was even turned into a cauldron with green smoke coming out of it. Admittedly the weather wasn't great, but the clouds did come and go allowing some viewing of the night sky. What was great was that it attracted a whole different crowd of people to the normal star party.

Now I'm off to get some sleep.

Posted in astro blog by Stuart on Saturday 16th Jul 2005 (02:17 UTC) | Permalink

A replacement for Soyuz

Another of the world's big space nations has decided to re-invigorate their human space flight programme with mentions of Mars. This time it is the Russians. According to a story on the BBC News website, the Russian government have approved a plan to provide money for the development of a reusable spacecraft to replace the Soyuz manned launch vehicle. They also want to put six volunteers in a mock-up of a Mars module for 500 days. This will be based in Moscow and apparently has 20 volunteers already. Megan has suggested that it sounds a little bit too much like the Big Brother TV show.

Posted in astro blog by Stuart on Thursday 14th Jul 2005 (19:10 UTC) | Permalink

The magic of astronomy

When I was a kid I was fascinated by magic. I don't think I ever thought that magic tricks were real; they were just that - tricks - and I always wanted to know how they were done. I had a Paul Daniels magic set and I would watch magic shows on TV looking for strings, trapdoors or clever camera angles. As I grew older, that desire to understand how stuff works has remained with me but now it gets called science.

Most kids are interested in magic. You only have to look at the numbers of kids around the world that have read the Harry Potter books over the past few years. The series is a phenomena and the books have been translated into numerous languages including Latin and Welsh. Surprisingly perhaps, the books contain quite a few astronomical references.

I first really noticed this while going to primary schools with an inflatable planetarium. Inside the planetarium I usually describe the constellation of Orion and show how the stars of the belt point down to Sirius. These days this elicits whispers of 'Oooh, Sirius Black' from the children as they sit in the dark. For those of you that haven't read Harry Potter, Sirius Black becomes quite an important character and can turn himself into a large black dog. Conveniently, this lets me explain that Sirius is also known as the dog star and is in the constellation of the Big Dog (Canis Major). However, Sirius Black is not alone as there are other characters with celestial names; Andromeda Tonks, Bellatrix LeStrange, Draco Malfoy and Regulus Black. Perhaps I should thank J.K. Rowling for all these modern aides-memoire.

The next book - book 6 of 7 - is due out at 00.01 BST this Saturday. In the UK, bookshops open up at midnight on the day of launch so that thousands of eager children can get their copy. With thousands of kids having permission to be awake in the middle of the night (accompanied by their parents of course) wouldn't it be fantastic if they could combine a star party with buying the book? If they live in the north west of England they can. Jodrell Bank Observatory's Visitor Centre is having a combined star party and book launch this Friday night. There will be a solar telescope (for seeing the Sun before it sets), optical telescopes (perhaps having a look for SN2005cs), astronomers to answer those difficult questions, a 3D trip to Mars, a planetarium, face painting and more. The magic starts at 9.00 pm BST Friday and goes on until 0.30 am BST Saturday. If you want to attend, you should book in advance with the Visitor Centre.

Posted in astro blog by Stuart on Wednesday 13th Jul 2005 (23:33 UTC) | Permalink

The centre of the Galaxy

Galactic Centre
IMAGE: A HKL colour composite of the Galactic Centre region. The central black hole is located in the centre of the box. CREDIT: Max-Planck-Institut fur extraterrestrische Physik.


At the centre of the Milky Way sits a supermassive black hole. But how exactly do you see something that captures all light that goes near it? The answer is by inference; you watch what happens nearby and infer what is there using some standard physics like you might do in school.

Our galaxy, the Milky Way, appears as a faint white band of 100 billion stars across the sky. It is actually a spiral galaxy but looks like a band because we live inside it. In one of the arms to be precise. The centre of the Galaxy is in the direction of the constellation Sagittarius. The very centre, the supermassive black hole, was properly identified in the 1970s by the detection of radio waves from an area named Sgr A*. Within a few light years of the centre are ten thousands of stars. This makes it a very dense region indeed as near the Sun the typical spacing of stars is about 4 light years.

Astronomers at the Max-Planck Institute have been observing this region, using the New Technology Telescope (NTT) and the Very Large Telescope (VLT), since 1992. They study the stars motions which are possible to see, with a suitable telescope, as the stars are moving quite quickly near the centre. They have created a nice mpg movie showing the motion of the stars in a region of space about 20 light days across (about 40 times the distance of Voyager 1 from the Sun).

By splitting the light into its constituent colours - a technique called spectroscopy - they can identify the elements that make up the outer layers of the stars they observe. This is a bit like cosmic fingerprinting. Doing this, they have found that there are three types of stars near the centre; those giving out light from helium (He I), those which contain carbon monoxide (CO) which absorbs some of the light and relatively boring stars with featureless spectra. This seems to imply that at least two periods of star formation have occurred in the centre of the galaxy.

Using all their observations, at different parts of the spectrum from radio light to X-ray light, they suggest that the central black hole has a mass of about 3.6 million solar masses (a solar mass is 1 million times the mass of the Earth) and is spinning about half as fast as the theoretical maximum spin rate.

Posted in astro blog by Stuart on Tuesday 12th Jul 2005 (15:56 UTC) | Permalink

A chance sighting

Tonight it was clear. Well, not that clear but good by Manchester standards. With a pleasant outside temperature - not too hot or cold - I thought I would just sit out in the back yard and watch the stars come out with a nice cup of tea. It was very relaxing despite the sound of traffic and the occasional siren in the distance.

My back yard is tiny and I am surrounded by buildings, so my field of view is quite limited. I watched as Arcturus became visible in the west and then found the three stars of the summer triangle - Vega, Deneb and Altair - over in the south-east. I lay on my wooden bench looking up and trying to see how many stars I could make out. As it got darker, the street lights started to kick in and the sky seemed to get a bit brighter again. On top of the man-made light, I was also battling against some thin cirrus and contrails which seemed to be becoming more widespread. Still, it was a warm night and it was great just to lie there watching Arcturus shine 200 million, million miles away.

Suddenly, not far from Arcturus, I spotted a bright light that was moving towards the south. A plane was my first thought, as several had passed overhead already, but there were no flashing wing lights on this one. My next thought was the International Space Station and, sure enough, the front page of Heavens Above showed the ISS over southern England and northern France. I watched it as it passed behind my neighbour's roof and then fade out as it went into the Earth's shadow. It was somehow strange to think that directly below that moving point of light was France. It makes you realise quite how small this planet of ours really is.

Posted in astro blog by Stuart on Saturday 09th Jul 2005 (23:28 UTC) | Permalink

SuitSat

The Amateur Radio on the International Space Station (ARISS) project will probably create one of the strangest ever Earth satellites this autumn. The plan is to install a radio transmitter in a surplus Russian Orlan spacesuit and launch it during a space walk. The suit, dubbed 'SuitSat' will send voice greetings to commemorate the 175th anniversary of Russia's Bauman Moscow State Technical University, have a video camera in the helmet and contain a CD of school children's artwork.

Posted in astro blog by Stuart on Saturday 09th Jul 2005 (00:24 UTC) | Permalink

London

OK, I know that this isn't anything to do with astronomy, but I hope you won't mind me mentioning it here.

In case you don't know, London suffered a series of bomb attacks this morning at 08.51 BST, 08:56 BST, 09:17 BST, 09:47 BST; a time of day when the buses, trains and Underground are full of people. It seems that one bus exploded and there were three explosions on the Underground. The current number of fatalities is thought to be at least 33. The number of fatalities on the bus explosion haven't been confirmed. The BBC have pictures and video of the scenes. There was no warning.

This was obviously an organised, callous attack and was timed to strike at the worst time. Yesterday, London was celebrating after successfully winning the Olympics in 2012 and this week the police force are concentrating on protecting the G8 leaders in Scotland.

The mobile phone networks around London have been finding it difficult to cope with the volume of calls that are being made. As far as I can tell at the moment, nobody I know has been killed or injured. I did know some people going to the Royal Institution in London this morning, but it seems that they are OK. Thank goodness.

My deepest sympathys go to the families and friends of all those that died in today's terrible attacks.

Posted in astro blog by Stuart on Thursday 07th Jul 2005 (16:33 UTC) | Permalink

SALT mirror completed

SALT primary mirror
IMAGE: SALT primary mirror completion, SAAO/SALT
Since 2000, the South African Astronomical Observatory (SAAO) have been building the South African Large Telescope (SALT). This is now the largest optical telescope in Africa with a staggering 11m primary mirror (look at the person in the picture to get an idea of the scale). The design is based on the Hobby-Eberly Telescope (HET), in Texas, and is made up of 91 hexagonal mirror segments. I saw the first few segments in place back in 2003 and it has been a delicate job since to put all the segments together. Each segment is 1m across, 100 kg in mass and has to be positioned using special cranes and winches. During installation, the telescope engineers had to be careful not to drop anything!

In May this year the primary mirror construction was completed and SAAO have some pictures of the final stages on their website. The telescope will be inaugurated on 10th November 2005.

The largest telescopes on the planet such as the VLT, SALT and Keck are four to six times the diameter of the HST. Looking ahead twenty years, the next generation will be the extremely large telescopes (ELTs); around 50-100m in diameter. The European large telescope project was previously known as OWL but is now referred to as ELT because the name wasn't considered serious enough.

Posted in astro blog by Stuart on Wednesday 06th Jul 2005 (12:52 UTC) | Permalink

The view from space

Wow! Paul Feldman and Hal Weaver at the Space Telescope Science Institute have been working hard and already released images of the impact taken with the Advanced Camera for Surveys (ACS) on the HST. Actually, the HubbleSite has another frame taken at 07.20 UT. Comet Tempel 1 brightened up so much that the diffraction spikes are visible on the middle frame taken at 06.01 UT.

ESA's Rosetta probe, which is going to a comet itself, took images every five minutes around the time of impact using the OSIRIS Narrow Angle Camera. The have made a nice 3D surface plot to show how the brightness changes and a traditional light curve too.

XMM-Newton's optical monitor (it is actually an X-ray telescope) caught images in the blue and UV parts of the spectrum. They were able to measure the brightness of hydroxyl groups and saw that they increased by a factor of about five from before the impact to an hour and a half afterwards. Cool or what?

Posted in astro blog by Stuart on Monday 04th Jul 2005 (23:05 UTC) | Permalink

An Einstein ring

One hundred years ago, Einstein developed his theories of relativity (Special first and General later) which helped describe extreme events that Sir Isaac Newton had no experience of. Apart from telling us that the speed of light was a constant (in a vacuum), they also told us about space-time and how it interacts with matter.

When you stick a lump of mass in empty space it distorts the space around it in the same way that a lead ball bends a rubber sheet, although this is in three dimensions rather than just two. The distortion of space also affects the travel of light; a light beam can be deflected as it goes past a large mass. You can think of the mass (say a galaxy or cluster of galaxies) as a sort of gigantic lens that focuses the light from distant objects. Indeed, these objects are known as gravitational lenses for that very reason. The first gravitational lens, 0957+561, was found in 1979 by Dennis Walsh, Bob Carswell, and Ray Weymann. This radio object was seen to coincide with a close pair of faint blue fuzzies which both turned out to be the same distant quasar.

Gravitational lenses can actually tell you an awful lot of information about the distant quasar as well as the galaxy that acts as the lens. One of the most exciting things you can do is actually work out the distance to the quasar by watching how the images, created by the lensing galaxy, vary. Calculating distances may seem straightforward on the Earth, but they are traditionally very difficult to measure accurately out in the Universe as you can't just use a tape measure. To help work out some of these properties, many people carry out searches to find new gravitational lenses. Although the most obvious gravitational lenses have been discovered - they are the easiest to find - many searches are still ongoing.

Now occasionally the quasar, galaxy and Earth will just happen to line up. When this occurs a circular ring of images, of the distant quasar, are formed around the lensing galaxy. This beautiful distortion of light is known as an Einstein ring in honour of the gentleman whose theories helped explain them. The most famous example is an object named 1938+666 which has been imaged in both the radio and optical parts of the spectrum. Now, astronomers using the VLT in Chile have seen another. This one is known as FOR J0332-3557 and is in the southern constellation of Fornax.

Einstein Ring
IMAGE: Einstein ring seen with VLT/FORS1, ESO.


The image above is a composite made from two colour bands (B and R). You can see the ring in the centre of the image surrounded by a whole host of interesting objects (click the image above to see a full-size version), some as faint as magnitude 26. The lensing galaxy (the dot in the centre) is about 8,000 million light-years away from us and the distant quasar (forming the ring) is about one and a half times that. That is a LONG way indeed.

Posted in astro blog by Stuart on Monday 04th Jul 2005 (18:26 UTC) | Permalink

Tempel 1

Comet Tempel 1
IMAGE: NASA/JPL-Caltech/UMD
So now we finally get to see what comet Tempel 1 looks - sorry looked - like six minutes before it ran over NASA's Deep Impact probe at 10:52 p.m. PDT, July 3. The picture was taken by the probe's impactor targeting sensor and shows a potato-shaped nucleus.

What struck me were the features that look like impact craters. They seem to imply that the comet has been hit in the past and survived intact. So it probably isn't as loosely held together or as fragile as some may have thought.

The BBC's first episode of Stardate had an interesting segment where they looked at impacts on different types of material using a high speed camera. They fired a copper ball at a block of ice, candy floss, mashed potato and melons to demonstrate the possible outcomes. The ice stayed pretty intact but some large chunks were blown off. The copper ball passed straight through the candy floss (not surprising). The mashed potato was quite interesting as it got splattered into quite a lot of bits.

By tonight (UK) we should have some initial science observations such as initial ideas about composition and structure. There should be some spectra - IR telescopes will have been looking for emission from water vapour released by the impact.

The Faulkes Telescope North - a telescope mainly used by school groups from the UK and Hawaii - has also been taking images from Hawaii.

I wish I wasn't on a dial-up connection today.

Posted in astro blog by Stuart on Monday 04th Jul 2005 (12:55 UTC) | Permalink

The time zone

Converting between time zones can be quite tricky. You have to remember how many hours behind or ahead the time zone is, from GMT/UTC, and then remember how many hours ahead or behind your time zone is. This is easier for those living on 0 longitude, but then you still have to factor in daylight saving.

I recently made a mistake with the time of impact for the Deep Impact probe. The times were quoted on the JPL website in Pacific Daylight Time. When I converted them into UTC I was out by an hour. Doh! To solve this problem for both myself and you, the reader, I decided to create a script that would automagically convert the times that I write into your current timezone. So, if you put your mouse over the time 09.14 BST, it should tell you what this is in your local time zone - assuming your computer is set correctly.

I threw the script together quite quickly so I'm sure there will be problems with it. Here are some test times: 09.14 ACST, 8.43 pm CDT, 3.13 am CEDT, 10 am GMT, 01.56 am NFT.

Posted in astro blog by Stuart on Monday 04th Jul 2005 (00:37 UTC) | Permalink

Stardate with a comet

With the imminent encounter, of the Deep Impact probe with comet Tempel-1 tomorrow, here is a quick update of how to watch. The BBC/Open University will be broadcasting the occasional astronomy programme, Stardate, tomorrow morning on BBC1 (11.45 BST) and a summary programme in the evening on BBC2 (20.00 BST). It will be presented by Lucie Green and Brian Cox. Lucie Green presented last year's Stardate (transit of Venus) along with Adam Hart-Davis. Brian Cox was in the band D:REAM (famous for Things can only get better; the Labour party's election song in 1997) but left them to become a nuclear physicist at the University of Manchester!

Of course, you can also watch on the internet; see here and here for comprehensive list of links.

Posted in astro blog by Stuart on Sunday 03rd Jul 2005 (14:37 UTC) | Permalink

A radio telescope

Secondary focus of RT4

Wheels at the base of the RT4 radio telescopeA few days ago, when I mentioned my trip to the Torun RT4 radio telescope in Poland, I promised some pictures of the dish. I've now got around to uploading some images so here is a mini tour of the telescope I visited.

Radio telescopes tend to have alt/az mounts, rather than Equatorial, as this is easier to engineer for large structures. So they rotate around horizontally (azimuth) and up-down (elevation or altitude). The azimuthal rotation is usually done with wheels on a railway track. The image to the right shows one of the sets of wheels at the base of the RT4. There are four sets of wheels on the outer track and some more on another track in the middle.

Climbing over the railway track, you can then ascend a metal staircase to reach the focus cabin underneath the dish surface. Climbing up some ladders you reach the top of the focus cabin and the place where all the radio receivers sit; the focus of the secondary mirror. You can then open a submarine-like hatch and climb out onto the surface itself.

On a sunny day the primary mirror can be dazzling as it is painted white and therefore reflects a lot of light. The surface is made from about seven rings of metal panels which reflect radio waves up to the secondary mirror. This is held in place by support legs which are just like the ones on the James Clerk Maxwell Telescope. The secondary mirror (see picture above) then reflects the radio waves down to the receiver cabin, in the middle of the primary mirror, where they are detected allowing astronomy to be done day or night.

It really isn't that different from an optical Cassegrain telescope, although you can't walk around inside a Meade LX200!

Posted in astro blog by Stuart on Saturday 02nd Jul 2005 (02:36 UTC) | Permalink

Cometary rendezvous

NASA's Deep Impact space probe is approaching its target; Comet Tempel 1. I haven't really mentioned it here as others, such as Tom and Ian, are doing an excellent job of keeping us informed of the current status.

Impact will occur at about 5.52 am UT 10.52 pm PST on Monday July 4th. Unfortunately, Europe won't be able to see the impact, as we will be on the wrong side of the planet at the time. Typical! Luckily, the wonderful people at NASA TV (satellite and web) and ESA TV (satellite) will be broadcasting the event live, so you can still watch it. You will also be able to see frequently updated images from Kitt Peak Observatory.

Posted in astro blog by Stuart on Saturday 02nd Jul 2005 (00:34 UTC) | Permalink

SN2005cs


IMAGE: Wolfgang Kloehr
When a large star gets to the end of its life, it runs out of the fuel that keeps the nuclear fusion going in the centre. At this point, the delicate balance of gravity and radiation pressure (caused by the nuclear reactions in the centre) is messed up and the star explodes violently as a supernova explosion. For a short amount of time after the initial explosion - perhaps days to weeks - the supernova can outshine all the stars in a galaxy. Watching how the light of the supernova fades tells us quite a bit about what actually happened to the star.

On the 27th/28th June Wolfgang Kloehr, from Germany, discovered a new supernova in the galaxy M51. The supernova, named 2005cs, is currently at a magnitude of 13.5 but is still rising. If you have your own telescope and are in a very dark place, you may even be able to observe it. If you want to have a look, you will need to point towards R.A. = 13h29m52s.85, Dec. = +47deg10'36".3. Due to the high declination, this is mainly going to be visible to observers at northern latitudes.

Thanks to Megan for telling me about this one.

Posted in astro blog by Stuart on Friday 01st Jul 2005 (12:48 UTC) | Permalink

Planets again

Last night I managed to see Mercury and Venus from an airfield in Torun, Poland. Saturn seemed to escape me again for some reason. I'm not sure why, as I think it was supposed to be comparable to Mercury in brightness. I suppose there is a lot more sky, to absorb the light, even when it is only a little nearer the horizon. I also got a good view of all four Galilean moons around Jupiter.

Tonight I flew back to the UK and was really hoping that the plane would be delayed by half an hour. If it had, I would have been able to look for Mercury from 36,000 ft. No clouds to spoil the view there! As it turned out, the plane was on time so started its descent before the Sun had had chance to get much below the horizon. It was a pity, although I did get a good view of part of one pretty amazing planet; the Earth.

Posted in astro blog by Stuart on Friday 01st Jul 2005 (00:53 UTC) | Permalink
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