Bertie and the Aliens

January 13, 2009

Back in the summer I bought a little plastic telescope for three dollars at a yardsale. I used it to look at Jupiter from the backyard. Seeing a disc appear was a very satisfying experience. I have a good pair of binoculars, but they are wide angle; good for getting the sparkled splendour of a field of stars, but no good for planets. Now, I am very far from being an expert amateur astronomer, but I do feel that some minimum level of concrete connection with the world outside the Earth is healthy for anyone claiming to understand the physical behaviour of the universe.

Many professional astronomers are dismissive of amateur knowledge and skill. There is a story of two well known senior astronomers gathering on the catwalk of the AAT waiting for twilight to run its course. Joe, an experienced Canadian observer, says “Hey, look at Canopus. That is a real sight.” “Oh”, says Bertie, an old fashioned loud upper class English type, “where’s that ?”. “What ?” says Joe. “You don’t know where Canopus is ?”. “Look,” says Bertie, “I’m an Astronomer not a bloody boy scout”.

As I tell that story, I can’t decide who I’m with. Some days it would definitely be Bertie. Professional astronomy is not train spotting. The point is to understand the physical processes in the Universe, not to collect pretty stars and memorise their co-ordinates. But if you are not careful, professional astronomy can be just a game in your head. That way lies string theory… Every so often its good to be reminded that what we work on is real.

Meteor storms are ideal for this. The cosmos comes to us. The best ever for me was the Leonids, just a few years back. Old seadog Mike Hawkins was holding a party out in the East Lothian countryside, and the sky just came alive. Streak after streak, bright, long, and coloured. I got a lift home with Eelco Van Kampen, and we watched them through the car windows, still bright enough to make your jaw stay open even as we got back to the Edinburgh city lights.

I have never seen a fireball come all the way to Earth. But as we live in the Age of YouTube, I can share the experience of others. Here is the video clip of the beast that fell to Earth in Canada just before Christmas, and here is a website with pictures of the whole slew of meteorites that Canadian scientists have collected since. (Thanks to the Bad Astronomer for posting the link.)

So I did one of those YouTube trail things, looking for more movies of fireballs. This had, umm, mixed results shall we say. But it turned up this gem … Just wait for the very last shot. You will love it.

Using Meteors to watch Polish TV

September 27, 2007

One man’s poison is another man’s meat. One man’s noise is another woman’s project. Radio telescopes see some odd things. Amateur astronomers miss half the best meteor showers. Polish TV is a nuisance. Or is it ? As Goethe said, connect, only connect. (Or was it E.M.Forster ?)

On Wednesday I was attending a meeting of the LOFAR-UK consortium. LOFAR is a project to construct a low frequency radio telescope array several hundred km across. It’s basically a Dutch project, but they are bringing foreign partners on board, partly to raise money and partly to expand the baselines. The UK consortium is planning several possible stations in the UK, maybe including one just outside Edinburgh, near where Dolly the Sheep was cloned. (A LOFAR station is hard to recognise as a telescope, being a collection of mesh tiles and odd looking metal spiders in a field…but all connected to an ultra-fast fibre link.)

LOFAR is appealing to a broad range of scientists. Years back, classical radio astronomy was entirely about exotic and violent things like quasars and pulsars, gravitationally collapsed and/or squirting out relativistic plasma. But now its part of the mainstream, with useful data on the interstellar medium, the early universe, star formation, stellar coronae, etc. Now the solar physicists and the space plasma folk are really interested too.

Ger De Bruyn gave a talk showing results from the first test station in the Netherlands. They made a map of the whole Northern Sky, and rediscovered the same sources Cambridge radio astronomers found in 1959. So far so good. But he also showed lots of raw data showing all the artefacts and radio frequency pollution you have to deal with. Some of this is cute. As Low Earth Orbit Satellites fly past, you can see them change frequency due to the Doppler effect. Some of it is very loud noise – Cas A and the Sun are horribly bright, and the Sun has a nasty habit of flaring erratically, as he showed in some data with 21 msec resolution. Suddenly Lyndsay Fletcher from Glasgow got excited. “Ooo give me that data” says she. “Are you sure?” says Ger, “its just a test run to see if we can clean the data”. “Yes I am sure” says Lyndsay, “we’ve got data at every other wavelength on the same flare – this is the missing link”. OK – science with LOFAR has started !

Next Ger showed how at one frequency Danish TV gets in the way, and at another frequency its Polish TV. (77 MHz if you want to tune in). The plot had a whole bunch of spikes. “That” says he “is the Perseid Meteor Shower”.

Being a dumb X-ray astronomer at heart I checked this with old hand Adrian Webster. Was the Polish TV signal really bouncing off the meteors ? Not quite, it seems. The meteors create an ionised trail as they burn through the atmosphere, and it is these trails which reflect the radio waves. So is this a discovery ? Nope, says Adrian. Bernard Lovell found the same thing at Jodrell in the 1950s, and claimed that all the best meteor showers were in the daytime…. There is a website run by the Marshall Space Flight Center which has a good explanation, and where you can even listen to radio meteor trails.

Ok, so I am catching up. Its still new to me. But the more I think about it the more bizarre and beautiful it seems. We bring together a field full of wire that can look at the edge of the Universe and an oscillating signal encoding pictures of people in Poland, and suddenly we can see small pieces of rock, unaltered for four billion years, finally streaking into oblivion above our heads.