Bad Astrologers II

It is that time of year again; the start of a new one. The newspapers will be full of horoscopes for the coming year. Many people will believe these predictions despite the (western) zodiac signs being based on an out-of-date version of the sky. Oh, that and having no basis in reality but I digress.

Earlier in the year I reviewed the attempts of a bunch of astrologers, and assorted others, at predicting the results of the UK General Election. They didn't do very well. In fact they were rubbish. When it comes down to making actual predictions they don't perform any better than guesswork. Despite that, they do make a killing from all those premium rate phone lines. Why do I mention it now? Well, looking back through my website logs, I notice that that post has had a lot of visits from people looking for the astrologers mentioned. I hope that these visitors saw my poor review and stopped to get some astronomy while they were here. I can hope at least. On a related point, one visitor came here looking for the phrase "Phil Plait is trouble". I guess he is, but in a nice way ;-)

Have a great 2006 everyone!

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Posted in astro blog by Stuart on Saturday 31st Dec 2005 (12:33 UTC) | Permalink

The astronomy blogosphere

As usual, the holidays have been (and still are) busy. This, along with my inability to think of anything original, has meant that I haven't posted much recently. To take you through new year, here is a short round-up of what has been happening elsewhere on t'Internet.

Recently the weather seems to have been a bit poor for observing. This is quite normal in the UK, but it is most annoying now that we have long dark nights in the northern hemisphere. Christmas morning mist has been stopping Megan (UK) seeing the Lovell Telescope, so she made do with scanning in some old photos instead. Cloud has put Dave P (UK) in the doldrums while James (Ireland) has managed to get a couple of clear cold nights. I bet they weren't as cold as Tom (New England) is getting at the moment; he has been fitting out his new Sky Shack (think of a shed on a sledge) with a heater to keep him warm in the deep snow. It seems to be working a treat.

When the weather allowed, this month has seen lots of solar system observing from both hemispheres. Mars is getting smaller again, but that hasn't stopped people getting views of the major features. Venus has also been giving a good show as it overtakes the Earth on the inside and becomes a larger slim cresent. Saturn has also started to become sociable by rising earlier. This has allowed Rob (Florida) to get a nice shot of it.

Nearer to home, the Moon has been providing a good target for all. Ian (Australia) has a lunar mosaic, Math (Belgium) has a nice video trip across the Moon and Peter (New York City) has a great record of a night observing craters on the Moon. Perhaps he should enter it in Ian's competition (judge's

decision is final!) to find the best sky watching experience. Mind you, I would suggest Aditi's (India) experience of the night sky during a powercut as a contender too.

In other news, a small meteroid was caught on camera hitting the Moon, Stardust will be returning on 15th January and Uranus has gained two new rings (see Phil P or Tom). I still haven't been able to decipher that anagram yet.

Finally, Dave P has been encouraging the return of sketching (I've made you the "and finally" again Dave ;-) ) and Peter has taken up the challenge with some great sketches of the Moon. It would be nice to see more in the new year. Now, if only it wasn't foggy outside...

Posted in astro blog by Stuart on Thursday 29th Dec 2005 (18:56 UTC) | Permalink

Christmas on Mars?

Back on 31st October 2006 the British Rocket Group (also known as BERG) launched Guinevere One towards Mars. The trip has taken a very quick two months and the lander should be touching down later on today. Of course, the Prime Minister (Harriet Jones) has been claiming some of the credit for this mission (preparations for which started several years before her recent appointment), so she must be hoping that it doesn't go the same way as Beagle II did. Especially as the latest data from Mars Reconnaisance Orbiter still hasn't located the crash site. Whatever happens, there is bound to be coverage on the TV tonight.

Guinevere One should be landing at about 7pm GMT and shortly after it will begin transmitting live video images - with a delay of about 20 minutes due to the finite speed of light - from Isidis Planitia. Later, several robotic rovers will study the soil around the landing site as well as provide ground-based information about the martian weather. Since the Opportunity rover stopped working during the martian winter, we've been down to just one rover on the red planet. Hopefully there will be a few more by tomorrow.

Guinevere One is also carrying a suite of messages to alien life that are similar to those on Voyager I. This is rather bizarre, as there isn't thought to be any life on Mars and certainly none that could read! This is really just a publicity stunt to get press and public attention.

Of course, it isn't the end of 2006. Most of this post is fiction created to fit in with the special Christmas edition of Doctor Who.

Posted in astro blog by Stuart on Sunday 25th Dec 2005 (00:00 UTC) | Permalink

Stardust

Back on the 7th February 1999, NASA's Stardust spacecraft was launched. Its seven year, 2.88 billion mile, mission was a round-trip to comet Wild 2 (pronounced Vilt 2). I remember the launch because a year or so before it there was an opportunity to add your name to a microchip that would be on board. I added quite a few names of friends and relatives to that chip. (If you missed out you may still be able to add your name to the Dawn spacecraft, although this was recently asked to stand down.)

Stardust collected samples of dust from the comet's tail in 2000 and inter-stellar dust in 2002 using aerogel 'tennis racquets'. In January 2004 Stardust made the front pages of many newspapers when the mission team released images of the comet nucleus.

Now, if you were thinking ahead you may have noticed that 1999 plus seven years brings us to 2006 and indeed there are only 23 days (or is that 24 days?) before it returns with the dust samples. The samples will be released in a capsule from the main spacecraft and hurtle through the atmosphere at 12.8 kilometres per second finally landing in the Utah desert by parachute.

If you live in the western States of the U.S. you will be able to watch re-entry early in the morning  (3:15am) on January 15th. In fact the mission team would like amateur astronomers to take photographs or movies of the re-entry to help with their analysis of what happens to the heatshield at these speeds. If you are in the right place you could even catch it passing in front of the Moon. You can find out more at the Hypervelocity re-entries website.

Posted in astro blog by Stuart on Thursday 22nd Dec 2005 (18:47 UTC) | Permalink

Hunting the Beagle

The BBC report the possible discovery of the UK's Beagle 2 lander on the surface of Mars. Colin Pillinger claims that various light and dark areas in a crater, seen by NASA's Mars Global Surveyor, could be parts of the ill-fated lander. It was thought that Beagle 2 probably crashed during Christmas Eve/Day 2003 because the atmosphere was thinner than had been expected so there wasn't enough braking and it hit the ground too fast. It was the first British thing to crash on Mars!

Frankly, you may need to be someone like Richard Hoagland to see much in the images on the BBC news site. I think I'll wait for higher resolution images from Mars Reconnaisance Orbiter next year before celebrating.

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Posted in astro blog by Stuart on Tuesday 20th Dec 2005 (12:46 UTC) | Permalink

Favourite Image

It is the time of the year when every TV show seems to be the "Best cars/films/sporting events/ovens of 2005" or something equally thrilling. After seeing Tom's post about the Time Magazine image of 2005 I thought I would jump on the bandwagon and see what your favourite space/astronomy image of the year was.

Perhaps it was the view from one of the Mars rovers, the shadow of Hayabusa on asteroid Itokawa, Saturn's moons and rings seen by Cassini, the "Mountains of Creation" seen by Spitzer, water-ice on Mars observed by Mars Express, a deep impact on 4th July, the shadow cast by Venus or something completely different. Add links to you own favourites in the comments.

There is no grand prize for the winner - I'm just hoping that someone saw a great image that I didn't.

Posted in astro blog by Stuart on Monday 19th Dec 2005 (19:40 UTC) | Permalink

Hayabusa Returns?

The Japanese space agency JAXA doesn't seem to have been having much luck recently. First there was Mars-bound Nozomi spacecraft which suffered a technical fault just after launch in 1998. The mission controllers were able to save the mission by adjusting the course to include two fly-bys of the Earth. This increased the journey duration to about five years meaning that it would reach Mars at the end of 2003. Unfortunately, during the extended trip around the solar system, Nozomi had its electrical systems damaged by a solar flare. So despite the years of effort, ingenuity and tenacity the mission was doomed to fail at the final hurdle.

Fast forward to 2005 when the Hayabusa probe reached asteroid Itokawa. Everything seemed to have gone fine up until arrival. Since then it has survived the failure of several gyro-wheels, the loss of the Minerva probe due to a communications problem and more recently a fuel leak. Hayabusa's mission was to collect samples of the asteroid to return to Earth and it may have indeed collected something when it briefly landed a few weeks ago. However, the partial loss of fuel and a total loss of communication has meant a change of plan for the return journey. Originally it was hoped that Hayabusa would return in 2007 but that is now out of the question. The latest projections show that there is a 66% chance of a recovery in communication by early 2007. If this happens, a revised journey home is planned based on the amount of fuel left. That will take an extra three years arriving back in 2010 if all goes well.

Hayabusa return journey
The suggested return journey for the Hayabusa spacecraft. CREDIT: Courtesy of JAXA
JAXA are in good company when it comes to suffering set-backs in space travel - just think of NASA's Mars Polar Lander, Mars Climate Orbiter, ESA's Beagle II lander or the Planetary Society's solar sail. JAXA do an impressive job of coming up with work-arounds and fall-back plans. I really do admire their determination and hope they are able to return Hayabusa back to the Earth. Even if they don't, Hayabusa has already done quite a lot.

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Posted in astro blog by Stuart on Monday 19th Dec 2005 (02:17 UTC) | Permalink

Our neighbour in space

The Earth's moon is pretty beautiful isn't it? For thousands of years people have watched it, written poems to it and about it, treated it as a god and dreamed about visiting our closest neighbour in space. It would be awesome (in the full meaning) and humbling to stand on the Moon looking back at our blue-green planet. Just imagine the entire Earth hanging serenely over the lunar landscape like a huge glimmering bauble. So far, only twelve people have been lucky enough to have this privilege, but that may change in the not too distant future. Until we get there, we have to make do with watching the Moon from down here. The view's not bad though.

The Moon
The Moon on 18th December 2005 CREDIT: Stuart

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Posted in astro blog by Stuart on Sunday 18th Dec 2005 (14:27 UTC) | Permalink

Jodrell at Sixty

Yesterday was the sixtieth anniversary of Sir Bernard Lovell's very first observations at what became Jodrell Bank Observatory. Jodrell Bank is in the Cheshire countryside and was (and still is) the site of the University of Manchester's botanical grounds. On 15th December 1945 Sir Bernard made use of the botany huts and some radar equipment left over from the second world war to listen to echos from the Geminid meteor shower.

Over the following years the observatory grew up with various small dishes and in 1947 the 66 metre diameter transit telescope was built. This was the biggest radio telescope in the world at the time and basically consisted of lots of wires strung from a huge pole. Through the early 1950s Sir Bernard planned a 76m fully steerable telescope and this was finally completed in 1957 just as the space age began with the launch of Sputnik 1. At that time it was the largest fully-steerable radio telescope in the world and the only place that could track the carrier rocket of Sputnik.

Today, the Lovell telescope is still going strong. In fact it is better than ever following the surface upgrade of a few years ago. It is still the third largest steerable radio telescope in the world.

Posted in astro blog by Stuart on Friday 16th Dec 2005 (19:27 UTC) | Permalink

Buffy the theory slayer

Tom reports on the discovery of a Kuiper Belt object currently going by the temporary name 'Buffy'. The object is officially named 2004 XR 190 and was discovered by astronomers from Canada, France and the US. The object orbits the sun in a fairly circular orbit between 52 and 62 AU (about 7.8 - 9.3 billion kilometers) so is quite unusual; Kuiper belt objects normally have more elliptical orbits. Its orbit is also tilted at 47° compared to the rest of the solar system making it odd in more way than one. Both these oddities cause some difficulties for the current ideas about the way the Kuiper belt came into being. This will mean that more complex theories may have to be considered.

I presume the press-friendly name of Buffy takes its lead from Mike Brown's Xena earlier in the year.

Posted in astro blog by Stuart on Tuesday 13th Dec 2005 (19:04 UTC) | Permalink

Red sky at night...

...is a shepherd's delight. This is a popular saying in the UK. However, a red sky at sunset usually signifies an increase in dust particles in the atmosphere towards the west. This isn't half as poetic though. The picture below was taken this evening and shows a particularly pink sunset. It is very tempting to ascribe the vivid colours to smoke from the explosion that occurred on Sunday.

Sunset
Sunset seen following the Hemel Hempstead explosion. CREDIT: Stuart


In case you don't know, there was a massive explosion at a fuel depot near Hemel Hempstead in the UK. Amazingly, nobody was killed in the explosion but it has put - and is still putting - a lot of soot particles into the atmosphere over the south of England and Wales. The Met Office have flown through the expanding cloud in a plane and measured particles that range in size from one to three microns. These filter out the blue light, so will produce some dramatic sunsets in the UK (probably northern France too) until they get washed out of the atmosphere. I imagine this will also ruin the chances of many people seeing the Geminids.

No prizes for guessing what the structure to the right is.

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Posted in astro blog by Stuart on Tuesday 13th Dec 2005 (17:13 UTC) | Permalink

The Geminids

There are several good meteor showers each year and December brings us the Geminids. The peak is due around December 13th/14th but spotting 'shooting stars' will be difficult due to the brightness of the near full moon (or impossible due to cloud if you live near me). It is suggested that 20 per hour may be the best you can hope for this year even if you are at a good location. Still, it might be worth a try. My tips are to wrap up warm (at least two pairs of socks is essential for winter observers!) then lay down on a deck chair (lawn chair) looking straight up early in the evening or at about 45° later in the night. If you have radio equipment you can even try listening for Geminids.

I was reading about the history of observations of the Geminids and I see that the first person to note them was a man by the name of Robert P. Greg - a fellow Manchester resident (albeit 143 years ago). Of course back then there wasn't much light pollution to worry about but, in the heat of the industrial revolution, there may have been other issues affecting Manchester-based astronomers; factory smoke!

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Posted in astro blog by Stuart on Monday 12th Dec 2005 (00:18 UTC) | Permalink

Planets

For over ten years astronomers have been finding planets circling stars other than the Sun. The number has been increasing at a phenomenal rate and, as of the end of November, the total number of extra-solar planets stands at 170. These break down into 146 different systems, 18 of which have multiple planets. Currently, these planets are all very big - about the size of Jupiter or larger - and the hunt is on for the first detection of an Earth-mass planet. The trouble is that the bigger planets are easier to find than little ones.

Future space missions such as Kepler and Gaia should find more planets than you can shake a stick at.

Posted in astro blog by Stuart on Thursday 08th Dec 2005 (19:52 UTC) | Permalink

2004 MN4...again

If you remember back to the very start of the year you may remember mention of an asteroid that was going to hit the Earth in 2029. The asteroid had the name 2004 MN4 (having been discovered near the end of 2004) and measurements of the position of the asteroid had given it a rating of 4 on the Torino scale - the asteroid equivalent of the Richter scale - making it the highest rating ever. Even so, a rating of 4 just "merits attention by astronomers" (previously "meriting concern") although it helped fill up the pages of the major newspapers with graphics of asteroids hitting the Earth and size comparisons in units of Nelson's columns (or area the size of Wales). As more observations came in, the path of the orbit was refined, showing that it wouldn't hit the Earth, so the rating was revised downwards (as usually happens).

2004 MN4 - now named Apophis after an ancient Egyptian spirit of destruction - has made the news again (spotted courtesy of Davep). This is not because of any significant increase of danger but because it got mentioned at a recent meeting in London. Back in February the probability of impact with the Earth was put at 0.016% but has now slightly increased to 0.018% for an impact seven years later in 2036. It currently rates 1 on the Torino scale, so the "chance of collision is extremely unlikely with no cause for public attention or

public concern".

Posted in astro blog by Stuart on Wednesday 07th Dec 2005 (10:07 UTC) | Permalink

Eight Einstein rings

If you have a lot of mass you can bend light towards you. This was one of the consequences of the theory of general relativity and was first verified in an observation by Sir Arthur Eddington in 1919. He measured the change in position of a star that was seen to the side of the Sun during a solar eclipse. The star appeared to be about 1.75 arcseconds (about a thousandth the angular size of the Sun) closer to the Sun than it would be if the path of light wasn't bent. Basically the Sun was acting like a lens, focussing light. The effect is also predicted by Newton (obviously not personally) but he thought it would only be half that amount. So in the play-off between Einstein and Newton, Einstein came out on top.

All matter will bend light towards it as it passes by, just as the Sun does. If you have a massive galaxy of stars sat between the Earth and an even more distant galaxy, such as a quasar, the light from the quasar is bent around the nearer galaxy. This will usually produce two or four images of the distant quasar around the galaxy but you can also produce lots of interesting arcs of light if you have a cluster of galaxies. If you happen to have the Earth, galaxy and quasar perfectly lined up, you get a beautiful ring of light surrounding the lensing galaxy. This special case was also predicted by Einstein in a paper he published in 1936 and so they get called Einstein rings in his honour.

Adam Bolton, Leon Koopmans and others used the spectra of the light detected in the Sloan Digital Sky Survey to find a list of elliptical galaxies that they think may be candidates for gravitational lenses. They then used the advanced camera for surveys (ACS) onboard the Hubble Space Telescope to have a better look. Amongst the 50 galaxies that they looked at, eight were found to be Einstein rings (the blue arcs in the image). They still have another 50 or so candiate galaxies to look at so they may find some more.

Einstein Rings
Eight Einstein rings found using the HST and the Sloan Digital Sky Survey CREDIT: NASA, ESA, A. Bolton (Harvard-Smithsonian CfA) and the SLACS Team
Apart from being pretty, gravitational lenses also tell us loads of things about the Universe. You can use them to measure the size of the Universe and also find out about the density of galaxies. This is sort of obvious because you get fewer lenses if there aren't as many galaxies and if you have more galaxies there is more chance that some of them will line-up enough to give you a lens. Measuring the details of the arcs and images lets you also work out how much stuff - both normal matter and dark matter - is in the lensing galaxy so you can effectively weigh it.

You can see the same effect as a gravitational lens if you happen to have a broken wine glass (make sure you have a responsible adult with you ;-). Draw a large dot on a sheet of paper and hold it behind the broken off base of the wine glass. When you line up the neck of the glass with the dot you should get an Einstein ring.

Posted in astro blog by Stuart on Thursday 01st Dec 2005 (21:27 UTC) | Permalink
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