Beyond Einstein

I've said it before and I'll say it again; this is the International Year of Physics.The aim is to celebrate the amazing year of 1905 when Einstein published three incredible academic papers. As part of the many celebrations, on 1st December (Thursday) large physics laboratories around the world will be conducting a continuous 12-hour webcast called Beyond Einstein. The programme covers quite a range of topics covering the theory of relativity (16:00 CET), the creation (17:35 CET) and future (17:45 CET) of the web, antimatter (22:45 CET) and more. Astronomy-wise there will be a talk at 18:30 CET which will have live links to the Ice Cube experiment at the south pole. If you haven't heard of Ice Cube before, it is a cubic-kilometre sized observatory for detecting elusive particles called neutrinos. It sounds interesting.

Posted in astro blog by Stuart on Tuesday 29th Nov 2005 (22:40 UTC) | Permalink

How do astronomers drink in space?

Sometimes I like to look through my logs to see how people are getting to the site. This can throw up some interesting links but I also get an interesting list of search terms that people use to get here. For instance, you can tell what time of year it is ("address santa claus north pole") or what has happened recently ("asteroid Itokawa location"). Some people have more factual questions on their mind ("What is the average density of the sun?") or things more practical ("buying barn door mount"). I was quite amused to discover the search phrase "How do astronomers drink in space?". I guess the question is supposed to refer to astronauts rather than astronomers but it does beg the question of how an astronomer would drink in space. Anyone got any ideas?!

Posted in astro blog by Stuart on Tuesday 29th Nov 2005 (00:54 UTC) | Permalink

Picking up good vibrations

Recently I've been helping with the construction and testing of extremely sensitive instruments that should (hopefully) be launched into space. I think it is extremely cool that something I've been working with will end up 1.5 million kilometres from the Earth, so I thought some of you might be interested to hear about it.

The particular instruments I'm testing are radio amplifiers and are actually amongst the lowest noise amplifiers ever built at the radio frequencies involved. Noise - imagine the hiss between radio stations on an analog radio set - is something that astronomers have to battle with a lot because astronomical objects are often very faint and they get lost in the noise. To deal with noise from different sources there are different techniques e.g. for CCD cameras you can do a flat field, a bias frame and stack lots of images.

All electronic devices have a noise associated with them because the electrons that go whizzing around the circuits have a temperature. For small particles, temperature is related to how much they jostle about. The higher the temperature, the more they jostle and the larger the noise. To reduce the jostling, the circuits are cooled down. The receivers I'm working on get cooled down to almost the temperature of liquid helium (which is about -269°C/-452°F) and that makes the noise very low indeed. Mind you, it will have to be to produce brilliant scientific results.

To reach this kind of quality level, space hardware has to be top notch and boy that sure does take a mammoth amount of effort. Everything has to be checked, double checked and checked again a few more times just to be sure that it works perfectly. So far these amplifiers have taken several years to build and I've been involved with the testing process full-time over the last two months.

A couple of days ago we took part of the instrument down to a facility near Oxford to perform a vibration test. For this test the instrument is firmly attached to a large computer-controlled bench that can shake at a whole range of different rates. If fact it can vibrate at lots of different frequencies simultaneously - our range was from a few Hertz to a couple of kilo-Hertz. The bench is programmed to simulate what the electronics will experience during the real rocket launch. In fact, we only simulated 'half a launch' as the test was only performed for one minute. Still, one minute was pretty nerve-racking especially when the amplifiers experienced the equivalent acceleration of 77-g at one point! They could have literally shook to pieces.  Thankfully they survived in one piece and after re-testing back in the lab they were shown to still be working. Phew.

Now we just have to make the rest of them.

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Posted in astro blog by Stuart on Wednesday 23rd Nov 2005 (21:27 UTC) | Permalink

Space Cadets

The UK's Channel 4 are about to start a new reality TV show where they send the winning contestants into space. The programme called Space Cadets sounds too good to be true and it is. The programme aims to trick nine carefully selected contestants into believing that they are competing to be launched. The 'best four' will be awarded a fake trip into space but will not actually feel the effects of weightlessness as they will be sat on terra firma in a mock-up from the film Space Cowboys. The contestants are being told that "they won't be going into 'deep space' when weightlessness kicks in". Will they fall for it? Maybe. Will Channel 4 actually explain to the public why this statement is a load of rubbish? Probably not.

Posted in astro blog by Stuart on Thursday 17th Nov 2005 (18:16 UTC) | Permalink

Moon halo

Tonight isn't the clearest night of the year despite being very chilly. It isn't good for observing as there is quite a lot of high-level wispy cloud and plenty of airplane contrails. However, I had just got on my bicycle to go home from work when I saw a pretty amazing sight in the sky. Luckily I wasn't going fast, so I managed to stop before I went into a nearby hedge. That'll teach me to look up at the night sky whilst cycling. But what did I see? There was the Moon in the east with Mars about 20 degrees or so away around to the right. Near Mars was something that looked a bit like a curved vapour trail. Looking more carefully I realised that it made a full loop of the Moon. This was no vapour trail but a Moon halo.

Moon halo
Labelled image showing a halo around the Moon - 16 November 2005. Click for a larger version. CREDIT: Stuart
Just as rainbows are caused when light from the Sun is refracted by raindrops, crystals of ice high up in the atmosphere can refract moonlight to create bows and dogs. Whereas rainbows require raindrops in front of you and the Sun behind your head, halos are seen in 22° arcs around a bright object such as the Sun or around the almost full Moon whenever there are hazy cirrus clouds about. As the light is refracted, different colours are bent through different angles just as in a prism. Although this happens with a Moon halo, the light is very weak so is difficult to pick up by eye. Hopefully, in the image above you can see the colours. Frankly, I am amazed that this came out on my camera.

The other feature of the photograph is a airplane contrail that was created as I was setting up my camera. If you look carefully, you can see that it even cast a shadow on the clouds below!

For great atmospheric effects such as 'upside down rainbows', supralateral arcs and pillars check out Les Cowley's site.

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Posted in astro blog by Stuart on Wednesday 16th Nov 2005 (23:53 UTC) | Permalink

Engage tractors

Picture the scene; an asteroid is discovered on a collision course with the Earth. What do we do? The usual suggestion is to follow the bad example set by Hollywood asteroid films and blow it up. As Phil Plait describes, this is a bad idea. It is much better to give the asteroid a nudge several years before it gets to us. Even a little nudge, long enough in advance, can put it a safe distance from the Earth. The only trouble is with how to apply a nudge to a spinning, rubble like mass of dirty ice or rock.

Recently EPSRC - the UK's Engineering and Physical Sciences Research Council - began a study of ways to deflect near Earth objects (NEOs). The latest edition of ABC Radio National's Science Show (a podcast is available) discusses one possibility that EPSRC may consider; using the attractive nature of gravity. The suggestion is for a massive spacecraft to go and sit next to a NEO which will then be attracted to the spacecraft (and vice versa) via gravity. The spacecraft then uses angled thrusters to slowly move in a direction away from the asteroid, dragging it along without ever needing to make contact with the surface. The resulting space tractor would tow asteroids out of harms way albeit very slowly.

Posted in astro blog by Stuart on Monday 14th Nov 2005 (19:54 UTC) | Permalink

Trouble at Itokawa

The Japanese Hayabusa spacecraft has just suffered another set-back according to New Scientist. The small Minerva (Micro/Nano Experimental Robot Vehicle for Asteroid) probe that was due to hop around on the surface of asteroid Itokawa has drifted off into space.

It seems that the loss occured due to an unfortunate series of events. It started when altimeter measurements mis-judged the distance between the main spacecraft and the asteroid. When the mission specialists realised that they were only 100m from Itokawa they decided to release Minerva which doesn't have its own thrusters. However, that decision coincided with an antenna changeover back here on the Earth which resulted in a delay before the command could be sent. In the mean time, Hayabusa's thrusters had fired automatically to maintain a minimum height above the surface of the asteroid. So, when the command arrived, Hayabusa was not where it had been - it was moving away from the asteroid. That meant that Minerva was released at a relative speed of 15cm (6 inches) per second away from the asteroid. With an escape velocity of 13cm per second, Minerva could do nothing but escape.

I will have my fingers crossed for the remainder of the mission. Once again it shows that space is difficult.

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Posted in astro blog by Stuart on Monday 14th Nov 2005 (13:09 UTC) | Permalink

SALT first light

Africa's largest telescope, SALT, had its Inauguration on Thursday when it was officially opened by the South African President Thabo Mbeki. SALT is an 11-m telescope constructed from 91 separate hexagonal mirror segments and is based on a similar design to the Hobby-Eberly telescope in the USA. The design is very unusual for an optical telescope as it doesn't drive in Right Ascension and Declination but rotates in azimuth as most radio telescopes do. However it doesn't tip in elevation. This might make you wonder how it can track an object on the sky. Well, rather than tip the main mirror - which would deform because of gravity - it moves the instruments (e.g. camera) to compensate. In effect the eyepiece moves while the telescope stays still.

SALT
The South African Large Telescope at the South Africa Astronomical Observatory, Sutherland, South Africa CREDIT: Stuart


SALT tea room
The tearoom at SALT, SAAO CREDIT: Stuart
I was lucky enough to visit the South Africa Astronomical Observatory a couple of years back and I got a tour around SALT as it was being built by an international team of engineers. At that time there were only a few mirrors in place but it still looked pretty impressive. In the image above, SALT is inside the big shiny dome with the column next to it. The top of the tower sits at the centre of curvature of the main mirror and every so often they use this to check the shape of the mirror. The air conditioning and various utilities are in the short building to the left.

The telescope dome itself is pretty huge and has plenty of rooms. There is a main control room with a viewing gallery so the public can make funny faces at the engineers and astronomers on duty. If you have ever spent a night observing you will know that it often gets cold and, to keep awake, astronomers drink copious amounts of tea or coffee. I am glad to say that the dome has its very own tea room (see my sneaky picture to the left).

Back at the start of September SALT released the first light images. They aren't the best images ever taken, as there seem to be some issues with matching up the images taken with different colours filters, but they are the first with a new telescope so they will improve. I can't wait to see more.

47 Tuc
SALT first light image showing globular star cluster 47 Tucane located about 15000 light years away. CREDIT: SALT

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Posted in astro blog by Stuart on Saturday 12th Nov 2005 (23:20 UTC) | Permalink

The Time Lords

The International Telecommunications Union are currently discussing the removal of leap seconds. To summarise the debate, astronomers want to keep adding leap seconds every now and then to keep our clocks in sync with the rotation of the Earth. However, computer programmers (and the US military) would like to remove them because they are annoying to implement in software. Who wins? The ITU will decide soon (possibly).

If you didn't see the last few minutes of Newsnight last night, I suggest you go over to the Newsnight website and 'Watch Again' (the video will only be there for another 14 hours though so don't dawdle). Skip forward to about 40 minutes 20 seconds and you will get Newsnight's take on the issue - they take it very seriously ;-)

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Posted in astro blog by Stuart on Friday 11th Nov 2005 (09:15 UTC) | Permalink

Where's Tom?

Is anyone else having trouble accessing Tom's Astronomy Blog? It appears to have been down since sometime on Sunday/Monday. I hope everything is OK over there.

Posted in astro blog by Stuart on Wednesday 09th Nov 2005 (20:57 UTC) | Permalink

ISS passes

I have just had a quick look at the Heavens Above website and discovered that the International Space Station (ISS) is once again visible from the UK. From Manchester we should get some good passes at 17:49 tonight (WSW to S toSE), tomorrow at 18:13 (W to S to SE) and several more over the next few days. These times and positions strongly depend on your location so select your country, enter the nearest city or town name and then select 'ISS passes' to find out the best times for you.

I had great fun earlier in the year pointing out the ISS to random passers-by in the street who were wondering what I was looking at. Sidewalk astronomy is great.

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Posted in astro blog by Stuart on Wednesday 09th Nov 2005 (11:16 UTC) | Permalink

Venus Success

The Venus Express spacecraft has successfully launched from the Baikonur Cosmodrome. This follows the unsuccessful launch of Cryosat and the power failure on the student built SSETI so must be a big relief to the folks at ESA. Venus Express was a relatively cheap mission as it reuses many of the instruments developed for ESA's tremendously successful Mars Express. As the name implies, this spacecraft is headed for our sister planet of Venus and will arrive there in April next year. Full science operations should be going by the 7th May.

Although the launch was during the middle of the night (UK time), Megan was covering the launch live. I hope she got some sleep.

Posted in astro blog by Stuart on Wednesday 09th Nov 2005 (08:26 UTC) | Permalink

Taurids

Over the weekend I managed to catch sight of several shooting stars. This was no mean feat considering the sheer number of fireworks being let off. Of course, shooting stars aren't stars at all, but meteors burning up as they enter the Earth's atmosphere. Most of the meteors I saw were Taurids - they appeared to originate from the constellation of Taurus - although I did see a sporadic meteor too. The Taurids are part of the debris trail of Comet Encke, through which the Earth passes at this time each year.

Over recent days there have been sightings of some impressive Taurids and this has increased the number of reported UFO sightings. Science@NASA have some recent pictures and more information about the Taurids.

Posted in astro blog by Stuart on Monday 07th Nov 2005 (11:24 UTC) | Permalink

Copernicus

Mikolaja Kopernika, known in English as Nicolaus Copernicus, was born in the town of Torun in February 1473. His father died when he was 10 and he was put into the care of his uncle - who later became the bishop of Warmia. In 1491, young Copernicus went off to university in Krakow where he studied mathematics but also did some astronomy. He then went on to the University of Bologna to study law and the University of Padua to study medicine. By 1503 he had been awarded a Doctor of Canon Law from the University of Ferrara. Talk about a perpetual student! Over the following years he worked as a doctor, a canon, a Commissioner for the region of Warmia, drafted currency reforms and made maps. However, throughout his life he kept up his interest in astronomy.

At that time in Europe, it was commonly thought that the Earth was at the centre of the Universe and the Sun, Moon, planets and stars orbited it once a day. This view was not so much based on evidence, as due to the prevailing religious doctrine based on the work of Ptolemy. This theory did not work very well because it was so poor at predicting the positions of the planets. To make the theory match the observations, a system of epicycles had been created, but this was horrendously complicated and still didn't quite meet the observations. Not knowing exactly where the planets were caused problems for navigation at night.

Copernicus, using his mathematical knowledge, gradually formulated an alternate arrangement of the Universe that had fewer assumptions. This was based on ideas of ancient Greek philosophers such as Aristarchus and put the Sun at the centre of all things with the Earth, Moon and planets orbiting it. One assumption Copernicus did made was that the planets followed circular orbits. This meant that he still needed to include epicycles to make things work. Later, once Johannes Kepler had shown that planets follow elliptical orbits rather than circular ones, epicycles would finally be removed and the maths become much more straightforward and better at predicting planetary motions.

Copernicus's ideas were quite revolutionary (in more ways than one) and he did not rush into publishing them. He did publish a paper in 1510 but it wasn't until 1539 that  a young professor named Rheticus encouraged Copernicus to publish all his work. This finally came out as a book titled De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) in the year of his death, 1543. According to legend, he saw the first printed copy of his book on his death-bed.

Copernicus, along with Galileo, Kepler and others, gradually overthrew the accepted philosophical/religious view of the cosmos by making observations, applying logic to what they saw and testing their theories. That is proper science.

Copernicus
A bust of Copernicus photographed with the world's third largest, steerable radio telescope looking in the same direction. CREDIT: Stuart

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Posted in astro blog by Stuart on Sunday 06th Nov 2005 (16:34 UTC) | Permalink

Fireworks

Remember, remember the fifth of November. In the UK it is Guy Fawkes night or bonfire night as most people call it these days. All over the country people have been building bonfires and letting off fireworks to celebrate the fact that Guy Fawkes didn't blow up Parliament or the King back in 1605. Nowadays it is an excuse to let off some fireworks and wave some sparklers around.

To keep in with the firework theme, here is a Hubble Space Telescope image of Hoag's Object, in the constellation of Serpens. Although it resembles a Catherine Wheel, it is actually a ring galaxy that is about 120,000 light years across and that makes it similar in size to the Milky Way. The outer ring consists of newly formed massive blue stars whereas the centre contains lot of older redder stars. How exactly it formed, nobody is sure, and that makes it really curious. Even more curiously, there just happens to be another remarkably similar ring-galaxy visible in the distance between the two rings.

Hoags Object
Hoag's Object CREDIT: Tiffany Borders and The Hubble Heritage Team

Posted in astro blog by Stuart on Saturday 05th Nov 2005 (23:59 UTC) | Permalink

Elsewhere...

Just in case you've had your head in the sand over recent days.... Pluto may have two newly discovered moons which were spotted in recent HST observations and bring the total for Pluto to three (the third being Charon). The Japanese Hayabusa spacecraft has been taking stunning shots of the surface of asteroid Itokawa - see the JAXA website for more details. Mars has been extremely bright in the night sky over recent weeks as it is relatively nearby at the moment - this has allowed folks to take some pretty fantastic images of the red planet (oh, and good shots of Venus too). Nearer to Earth, following the loss of Cryosat and the delay to Venus Express, the student built SSETI satellite has had power issues, although two (out of three) of the pico-satellites it release worked fine. And finally, how about a bargin basement method for safe solar observing.

Posted in astro blog by Stuart on Wednesday 02nd Nov 2005 (19:50 UTC) | Permalink
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