Does this mean nothing?

Just before I go off to bed, I thought I would check up on the blog and noticed a comment about the naming of stars. A guy named Jake had been given one as a present and was having difficulty finding it in the sky.

I presume he was looking up about his star on the internet and had stumbled across my blog entry in which I complain bitterly about star naming companies. I do get very annoyed by the star naming companies and I'm sure they annoy many astronomers around the world. These companies claim to have "official catalogues" but these are as official as me keeping my own list in the garden shed. They generally name stars that are very difficult to see by eye and quite often don't seem to exist. That makes the whole experience of trying to see the named star very disappointing. I know of many cases where such names were bought in good faith, as a meaningful gesture or in the memory of a loved one, and it is terrible when people find out that it isn't what they thought it was. As someone who has to deal with that side of things - as an astronomy person I get asked to point out where these stars are - I find the whole star naming business to be underhand and actually pretty scandalous. I also have the job of breaking the bad news to people and that just makes me look mean. I don't want to be mean.

Having read my post, Jake quite understandably asked "does this mean nothing then?" In Christmas spirit I'll say that it does mean something. Although it doesn't mean that his star name will be used or recognised by astronomers, it probably does means that he has a friend or relative who cares about him very much. The sentiment was there and that is what really matters on a day like today. Merry Christmas and happy New Year to all the readers of Astronomy Blog.

Posted in astro blog by Stuart on Tuesday 26th Dec 2006 (00:35 GMT) | Permalink

Santa Watch

At Jodrell Bank Observatory we have an image which shows the directions that the radio telescopes in the MERLIN array are looking. The image is updated every few minutes and today (and Christmas morning) it may be worth watching because the Saint Nicholas Orbital Watch Monitoring Array Notifications have been added. That means that every time Santa passes over Jodrell Bank (North West of England) he'll be labelled on the image just like the ISS and Envisat normally are. You may even make out the reindeer and sleigh. Of course, this is a passive system unlike the radar-based Norad Santa Tracking System.

For those that are interested, there is also a version of this without the Santa tracking but with the sky as seen by radio telescopes.

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Posted in astro blog by Stuart on Sunday 24th Dec 2006 (02:03 GMT) | Permalink

All change

In a few minutes from when I post this (00:22 UTC) we reach the point in our orbit where the Sun will appear the furthest south in the sky (for the point where it is currently midday). This is known as the winter solstice and the result is that this will be the longest night of the year for those in the northern hemisphere and the shortest night for those in the southern hemisphere. Of course the Earth will carry on its merry way, slowly causing the Sun to get higher (or lower for southern hemispherians) for the next six months due to the tilt of our planet. Right now it also means that the winter (read summer for southern hemispherians) constellations such as Orion are pretty high in the sky.

I've just been stood in a pub car park pointing out a few constellations to some friends. It was a bit tricky because the fog kept coming and going and Auriga and Cassiopeia were painfully high causing me a bit of a sore neck. Still, it is good fun telling people some of the Greek/Roman/African stories about the constellations.

The winter solstice should not be confused with the earliest sunset (which was a week or so ago) or with the point at which the Earth is closest to the Sun - that is in another couple of weeks at 20:00 GMT on 3rd January 2007.

Posted in astro blog by Stuart on Friday 22nd Dec 2006 (00:13 GMT) | Permalink

How many stars can you count?

The British Astronomical Association (BAA), in collaboration with the Campaign for Dark Skies (CfDS) are asking members of the UK public to participate in a nationwide survey of light pollution (via DaveP). The idea is to get as many people as possible to count the number of stars they can see bounded by the shoulders and knees (or feet) of Orion between the 20th and 24th December. Orion is a very easy constellation to spot so this should be fairly easy for most people to do.

If you want to participate, wrap up warm, have a hot drink and go outside for 10 minutes to let your eyes adapt to the dark. As your eyes are adapting you can find Orion in the south (around to the left from where the Sun sets) and identify the shoulders and knees.When you think your eyes have adapted, start counting stars. Once you are happy that you've counted as many as you can, submit your results on the BAA website. While you are outside and not too cold, have a look around at some of the other things you can see. I'll leave it to Ian Morison to tell you what you can see in the night sky during December (MP3: 3.5 MB).

It is just a pity that this isn't an international project.

Posted in astro blog by Stuart on Tuesday 19th Dec 2006 (15:54 GMT) | Permalink

Gamma ray signal

It is pretty well known that stars can brighten and dim on fairly short time-scales. These stars are called variables and thousands of amateur and professional astronomers monitor them regularly. But it isn't just in optical light that astronomical objects vary. It is almost 40 years since the first pulsar was discovered by Jocelyn Bell at Cambridge using a radio telescope. Pulsars are like cosmic clocks with a pretty regular cycle of 'ticks' as they rotate on their axes and the beams of radio waves they emit sweep past us. Now, for the first time, a regular clock has been found through observations with a gamma-ray telescope named H.E.S.S. in Namibia.

The High Energy Stereoscopic System (H.E.S.S) consists of four individual telescopes that are quite unusual. Rather than observing space, they are actually looking at our atmosphere. They look for small flashes of blue light known as Cherenkov radiation emitted by particle showers that occur when a gamma ray hits our atmosphere. By observing with several telescopes in different locations you can trace the flashes back to the point where the gamma ray hit and recover the direction that the gamma ray originally came from. So, you can make gamma ray images of the sky.

H.E.S.S. discovered a modulated gamma ray signal coming from a binary star system known as LS5039. I say binary star system but although one of the stars is a blue giant (20 times the mass of the Sun), the other is thought to be a black hole. It appears that these objects have orbits which take them from between 0.2 to 0.4 AU (1AU is the separation of the Earth and the Sun) of one another. The compact object interacts with the wind from the blue giant in different ways as it changes its separation and this changes the number of gamma rays that are produced. The number of gamma rays we detect on the Earth also depends on how the blue giant and companion are orientated with more gamma rays heading our way when the compact object is between us and the blue giant.

The best way to explore the Universe is to look in as many different ways as you can. I wish the ground-based gamma ray telescopes much success in the future.

Posted in astro blog by Stuart on Saturday 16th Dec 2006 (10:25 CET) | Permalink

Aurora Alert: Dec 15th

Overnight I got a couple of emails from the University of Lancaster's great Aurora Watch website informing me of a possible ongoing storm. Ian has been mentioning the possible activity for a few days since the outburst from sunspot group 930. If you are currently in a dark part of the world and at fairly northern or southern latitudes (e.g. nothern Europe, Canada, Siberia, New Zealand, Tasmania and South Africa) have a look and you may get to see the northern (or southern) lights.

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Posted in astro blog by Stuart on Friday 15th Dec 2006 (10:54 CET) | Permalink

Stardust Published

This morning the Italian newspapers all seem to have Stardust on their front pages - even the free ones! I thought there must be big news and I asked my Italian colleague to tell me what had happened. He tells me that the reporters are claiming that new results "prove" that we are all made of star dust. Although I thought this was likely to be reporter's hyperbole, the first thing I did when I got to work was to find out what has actually been announced.

You may remember that the Stardust mission to Comet Wild 2 was launched back in February 1999. I remember it because it was the first mission I was aware of that took a CD of names with it. As you can imagine, I added most of my family and friends to it. At the start of 2004 Stardust caught up with the Wild 2 and returned some images. It also exposed one side of an aerogel tile to the shower of particles streaming from the comet. As the comet originates out in the Kuiper belt, it was hoped that some of these small flecks of dust may originate from a time before the start of our solar system and so shed light on what conditions were like before the Sun "turned on". Stardust was also the first mission to return solid samples from another solar system body since the Apollo missions.

The reason for the sudden interest by the newspapers and TV is that today's Science Express has a special series of articles about Stardust (and there is a press release from JPL in case you need a subscription for Science) in which the preliminary science results from the mission are published. So what exactly has got the Italians (and the BBC) so excited? The news that seems to have made the press is the discovery of organic molecules (Science 15 December 2006: Vol. 314. no. 5806, pp. 1720 - 1724). Of course, organic molecules have been discovered in many different places in space and, rather than referring to life, the term 'organic' means that the molecule contains carbon and hydrogen. It's still quite exciting though.

The organic molecules that they've found are similar to those in interplanetary dust grains and carbonaceous meteorites, although they seem to have more nitrogen and oxygen. This suggests that the molecules brought back from Wild 2 are not the result of ejecta from stars or even chemical processes in the diffuse medium between stars but they are consistent with ices being heated by radiation in a dense cloud such as that surrounding our Sun when it was just a proto-star. The ratios of oxygen to carbon and nitrogen to carbon are also higher than for meteorites and even those seen by the Giotto spacecraft at Comet Halley. The paper suggests that it may be a new class of organic molecules not previously seen in extraterrestrial samples.

The cometary dust samples also contain some minerals that could only have formed at high temperatures. This is surprising because the comet originates in the outer solar system yet these minerals seem to have come from the inner solar system. The Stardust team suggest that this may infer large flows of material in the very early solar system outwards from the Sun.

So lots of results there and I don't have time just now to read the rest of the papers they published. But this is just the end of the preliminary phase and the in-depth science is actually only just beginning. Not only is there is still a possibility for Stardust and Deep Impact to visit further comets, but results from the other side of the aerogel (exposed to interstellar dust) are still to appear. Expect much more science from Stardust in the future.

Posted in astro blog by Stuart on Friday 15th Dec 2006 (10:43 CET) | Permalink

Earliest sunset

So which day of the year has the earliest sunset time? It isn't the winter solstice - December 21st/22nd - in case that was your guess. Using the USNO calculator, I reckon the earliest sunset in Cheshire (UK) is 15:50 GMT on 13th December (the days either side have the same time so I took the mean). So why should the earliest sunset not be on the shortest day? This is all because the axis of rotation of the Earth is tilted with respect to the Sun and the Earth travels in an elliptical orbit. It is very complicated to think about and John Holtz has a good page explaining it.

By the way, for those that care about these things, the Winter solstice for 2006 it

is at 00:22 on the 22nd December
.

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Posted in astro blog by Stuart on Monday 11th Dec 2006 (14:40 CET) | Permalink

Water on Mars? (yet again)

We have had many announcements of water on Mars over the last years and today sees another. This time it is a bit more interesting because there is now photographic evidence for flows on the surface. And not just flows or channels made millions of years ago (or by wind) but flows that have happened in the last few years. I present some "before and after" images from Mars Global Surveyor (now probably deceased).

Water on Mars - before and after
A new gully deposit in a crater in the Centauri Montes Region.
CREDIT: NASA/JPL/Malin Space Science Systems
And if that isn't enough, here are some perspective views of it.

Water on Mars?
A new gully deposit in a crater in the Centauri Montes Region. CREDIT: NASA/JPL/Malin Space Science Systems
Wow! It certainly looks like a flow of something to me. Even better, it isn't the only one. The MGS team also have a before and after image of a gully deposit in a crater in Terra Sirenum. The suggestion is that the flows look like they were created by a liquid (I agree) moving debris down the slope and that this liquid may be water (it may not be). Of course, liquid water won't last long on the surface of Mars due to the low pressure and temperature - it converts rapidly into a gas or solid - so any water would not flow far and indeed this flow does seem to stop. It is compelling to say that this is water sublimating. I worry that it may just be some other liquid though.

The announcement of water is probably going to overshadow the other announcement the MGS team have made which is the discovery of two recent impact craters. By recent I mean that they have happened since 1999. That MGS saw any at all in this seven year period is quite amazing because it only imaged 5.2% of the surface. Hopefully Mars Express and Mars Reconnaisance Orbiter will pick up the baton and discover a few more.

Updated 19:59 CET: NASA have an audio interview with Mike Malin, the principal investigator for the Mars Orbiter Camera on MGS, about this topic.

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Posted in astro blog by Stuart on Wednesday 06th Dec 2006 (19:47 CET) | Permalink

Moon Base 2020

According to BBC News, NASA has announced plans to build a base on the Moon in 2020. I have mixed feelings about this because I keep worrying that the science missions may suffer to pay for it.

The BBC article claims that the lunar poles have "a moderate climate and more sunlight" than other parts of the Moon. I would have thought that the sunlight was spread over a larger area as you got nearer the poles, so I don't understand why this would be so. Perhaps they get around the problem by building the solar panels vertically. There was also a sloppy use of terminology in the video report (may not be visible if you are outside the UK) which implied that the far side of the Moon is the same as the dark side. It isn't; you can often see part of the Moon that is in shadow from the Earth.

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Posted in astro blog by Stuart on Tuesday 05th Dec 2006 (12:53 CET) | Permalink

Beagle 2 and beyond

The Royal Institution of Great Britain will be holding a public lecture on the ill-fated Beagle 2 at the University of Central Lancashire, Preston on Wednesday 13 December 2006 (7.30 - 8.30pm). The event is free although the RI advise you to book ahead. Beagle 2 would have done good science had it survived to the surface of Mars intact back on 25 December 2003. Unfortunately, like many other missions to Mars, it didn't make it. Hopefully Mars Reconnaissance Orbiter will spot the wreckage as some point.

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Posted in astro blog by Stuart on Tuesday 05th Dec 2006 (12:06 CET) | Permalink

December Jodcast

It took its time but the December Jodcast (MP3: 23.5 MB) is finally out. This month, with it being almost the end of the year, we got a little silly and have our take on the Wizard of Oz for the intro/outro. Rather than a wizard we had the Great and Powerful Pod and he comes from New Zealand rather than Oz (groan). Somehow, we also managed to involve HAL and Dave in the outro again. In terms of astronomy, there is an interview with Cormac Purcell about masers (the microwave version of lasers) which can be used to discover things about stellar evolution, Tim talks about the Moon illusion and Ian M. (the northern one rather than the southern Ian M.!) tells us what we can see in the northern night sky during December.

In other podcast news, the Chandra Observatory has a video podcast about what clusters of galaxies can tell us (MP3: 24.0 MB), the December 2006 Astronomy a Go-Go (MP3: 22.3 MB) is online and so is Slackerpedia Galactica 4.0: The Astronomer Who Cried Wolf [FF] (MP3: 30.1 MB).

Posted in astro blog by Stuart on Monday 04th Dec 2006 (16:52 CET) | Permalink

Podcast ratings

The other day, whilst buying some presents on Amazon, I got to thinking about star rating systems. I often make use of them to get a rough idea if a product is any good. Of course, I also take into account how many votes have been made in an attempt to take into account individual biases. I wondered if I could create a rating system for astronomy podcasts on the Astronomy Media Player. Well I did make one and it is now live. I would be grateful if some of you could try it out and scream at me if it is horribly broken (I know it works in Firefox2 and IE6). This is partly driven by me seeing what I can do, but over time I hope that it adds some value too.

Posted in astro blog by Stuart on Friday 01st Dec 2006 (17:51 CET) | Permalink
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