Monday, May 28, 2012

macro, micro, stars, spiders

Two weekends ago, I viewed some globular clusters from the observatory on the Blue Mountains. For example, Messier 68 in Hydra at 39 000 light-years. I noted, at the time, that it was not very satisfying, the view. I must admit, globulars are probably my least favourite deep sky object to view visually telescopically. I'm not sure why. Maybe it is because, in general, they all look the same to me. Round fuzzy balls. Seen one; you've seen 'em all. OK. Maybe that's a little harsh.

Globular clusters are dense conglomerations of stars. They surround our galaxy, like bees around the Queen, slowly orbiting around the galactic core. They are generally old, filled with low-metal stars. Hundreds of thousands to several million. Each. Some suggest that they were the first objects to form in the galaxy. They are, for the most part, spherical. Very dense in the centre. Some globulars transfer from one galaxy to another.

Certainly when conditions permit, in a big 'scope, with a nice eyepiece, some of the closer, bigger globulars get interesting. When you can see individual stars, that's a little exciting. Seeing individual stars with slightly different colours and brightnesses makes it worth the look. When you start to think about what it would be like to fly through one, with a million suns all around your ship, light flooding in every port... that would be wild.

Many a time I've had a good view of Messier 13, the great cluster in Hercules. 26 000 light-years away. Seeing more stars than I can count, merging together toward a dense, intense, bright, crowded centre. The stars in the middle... they must be tripping over each other. Reacting to each other. Then following some of the stragglers outward, along invisible arms or tentacles.

I understand that Omega Centauri and 47 Tucanae are quite something. But I don't know if I'll ever get to see them.

The macro and the micro:

Last weekend, once again at the Carr Observatory, I came across a similar shape. It was Sunday morning. We were packing up and getting ready to leave, after the Open House and Awards Picnic. In fact, most people had already left. Grace and I were at the back deck. And I was on a chair, standing on the chair, so to string some more twine up the posts of the pergola. Trying to train the ivy plants skyward. And to spiral, if possible, up the verticals.

At the last post, along the west edge, just under the top lattice, I spotted a small sphere. At first I thought it a plant, a thistle, or a burr. But then I recognised it. A nest of spiders! Tiny yellow and brown baby spiders, possibly Argiope aurantia, huddled together, suspended in a fine web. I assumed they were keeping warm. I called to Grace and she had a quick look. I returned to the task at hand, measuring and cutting the twine.

A mama spider can lay 3 000 to 4 000 eggs. Like many animals, there's safety in numbers. For life to propagate, given that some won't make it, it is best to have a large litter. I didn't see mom around. Dad has probably been consumed.

When I looked back at the nest, I saw it now was very different in appearance. I didn't think I had touched the web directly but clearly I had caught the attention of the gaggle. Vibration through the wood, perhaps. The spiderlings were dispersing, the dense sphere now loosened, and the miniature spiders at the outer edge had moved away, along invisible threads. And that's when it struck me, these tiny creatures, with bodies about 1 mm across, in this current configuration, if I could freeze it, they looked just like M 13. Each little spider as a star. A spider cluster.

  • Messier 80, by NASA, via wikipedia
  • baby spiders, by xaliuqs, via deviantART

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