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David Darling's Newsletter #35


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February 3, 2006



Meanderings

Many thanks to all the folk who signed up to receive the newsletter over the holiday period and through January. And thanks also to everyone who's written in with suggestions for extra features on the website. Last time, if you remember, I mentioned the new forum that I'd set up. This is now starting to take off with threads on topics as diverse as artificial intelligence, gravity, and the search for life on Titan. I hope many more of you will join the discussions - whatever your interest or level of expertise. Start your own thread or have your say on one of those already underway.

Something else that people have been asking me about for a while is a blog. I pretty much put in anything that I find interesting on any particular day - it could range from what's making world headlines that day to something I saw while strolling around.

I'm also looking into RSS feeds for both the blog and the main website. The idea is to help you keep in touch with breaking news or other changes on the website, as soon as they happen.


Keep your e-mails coming. It's always good to hear from you.


In the News

These past few weeks have been a big time for news of little things. The discovery of a tiny fish - only 7.9 millimeters (a third of an inch) long when fully grown - in peaty wetlands in Sumatra has opened up a debate about what is the smallest vertebrate (animal with a backbone) on Earth. All the smallest known vertebrates are fish. But which deserves the title of "smallest of the small"? The answer isn't as straightforward as you might think. Take this new discovery of the miniature Sumatran fish. Here's my page on it with some pictures.

The researchers who found it claimed it was the smallest vertebrate in the world. But they admitted later that they hadn't heard of two earlier discoveries. One of these is the strangely named "stout infantfish" which makes it's living in the waters around Australia's Great Barrier Reef. Check it out here.

Lengthwise, this little guy seems to come in slightly under the 7.9 mm quoted for Paedocyprus. Shorter still, though, is the bizarre male angler fish of the species Photocorynus spiniceps. To see a very weird looking couple indeed (the male is the itsy stub that looks like a fin on the female's back), go here.

It turns out that the male Photocorynus is shorter from snout to tail than either of its two Lilliputian rivals. But how do you measure smallness - by length, volume, weight? The stout (but, in reality, very skinny) infantfish and its Sumatran rival may be a bit longer than the angler fish but they're quite a bit lighter. We'll just have to wait and see who makes it into the Guiness Book of Records next year.

Another ongoing debate where size is matters has to do with the recently found "tenth planet" of the Solar System. Its discoverers have nicknamed this world Xena, after the TV warrior princess, although its still officially known as 2003 UB313. Xena orbits the Sun way out beyond Pluto in a very elongated path that takes it into the so-called Kuiper Belt. Go here for all the specs, pictures, etc.

The exciting thing is that new observations have confirmed that Xena is definitely bigger than Pluto - by several hundred kilometers. Admittedly Pluto is the runt of the Sun's planetary litter but it's always been called a planet ever since its discovery in 1930. So if Xena is bigger than Pluto surely that means we'll have to call it a planet, too. Well, maybe not. Astronomers have got a problem on their hands because if they grant Xena planetary status, they'll have to do the same to every other Kuiper Belt object they find in the future that's bigger than Pluto - and there could be quite a few of them. Are we prepared to have 20 or 30 objects going round the Sun all of which are called planets? The alternative is to demote Pluto, which might be a smart move since it seems pretty clear now that the ninth "planet" is itself a body that came from the Kuiper Belt. On the other hand, Pluto does have 70 odd years of tradition on its side. No wonder astronomers are scratching their heads.

Still on the theme of "It's a Small World," astronomers last month announced they'd found the smallest known planet going around another star. If you think 2003 UB313 is a pretty obscure name for a planet then how about OGLE-2005-BLG-390Lb? That's the unprepossessing title for this most Earthlike to date of extrasolar worlds. It orbits a red dwarf star at the very remote distance of 25,000 light years and was detected by a method called microlensing. The dimness of its parent star combined with its fairly large orbit means there isn't much chance of Planet OGLE being inhabited. Its surface temperature is probably a very chilly minus 220 degrees C! Find out more here.

Let me know if you think Pluto should stay a planet. Maybe we can have a chat about it on the forum. That's it for now.

Best wishes,
David Darling