If not, I suggest you have a look at this beautiful set of time-lapse videos, taken of the shower in Joshua Tree National Park in California.

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The bright stripe of stars across the sky is of course the Milky Way - the spiral galaxy that’s our home, viewed edge-on from our position inside it. The dark patches are lanes of interstellar dust: compare them to the patches you see in Hubble photographs of distant spiral galaxies, and you’ll be reminded that we do indeed live in one of those things!

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[The embedded video isn't working for me, but I can't tell if that's just the computer I'm writing it on - if you have trouble, use the direct link above]

Perhaps more excitingly, you can see my housemate Joe Zuntz talking about the iPhone application he’s written for Galaxy Zoo. As I’ve mentioned before, Galaxy Zoo is an online project to enlist the help of thousands of members of the public in classifying millions of images of galaxies taken automatically by telescope, so that the data can be more effectively used for scientific study. With this new app iPhone users can classify galaxies during spare time on the train or elsewhere. (It’s a bit of a shame the BBC segment doesn’t mention that the main Galaxy Zoo website lets you classify them online without a smart phone.)

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Read the rest of Galaxy Zoo on the iPhone, and my house on the BBC!

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A short guide on how to look for them is here, but really you can’t go far wrong by heading out to an open dark area and looking up!

The Perseids last year. This is a combination of 227 separate images taken throughout the night and combined, to show the circular paths across the sky the meteors take due to the Earth's rotation. Click for credit.

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Read the rest of Perseids tomorrow night!

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And, I went to this exhibition as promised. I’ll have some things to say about that and maybe the conferences over the next few days.

In the meantime, here again is a video of Jupiter taken by Voyager 1 during its approach, for no better reason than that I find it absolutely awesome. You can read more about it at my post here.

Voyager 1's approach to Jupiter

It’s good to be back!

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The exhibition’s on until next Sunday. I’m going to try and make it down to London to see it, though I’m a bit busy at the moment with moving into a new house. But if any of you gets the chance to go, do let me know what it was like!

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[There is a video that cannot be displayed in this feed. Visit the blog entry to see the video.]

That was the Japanese spacecraft Hayabusa (Japanese for “peregrine falcon”), returning to Earth two days ago after a seven year voyage. It went to explore an asteroid called 25143 Itokawa, which orbits the Sun at an avergae distance a bit further than the Earth but closer than Mars.

Lots of other spacecraft have flown close by asteroids to look at them before, but Hayabusa did something special: it actually landed on the asteroid briefly, so it could collect a sample and bring it back to Earth. This is the first time that a manmade machine has landed on a celestial body other than the Moon and returned home, which is a pretty exciting first.

The plan was for the craft to fire some metal pellets into the surface of the asteroid, and catch the debris thrown up by the impact to bring back for study. Unfortunately though, a problem with the firing mechanism may mean that the pellets weren’t fired (it can be hard to be sure what’s going on on a robotic craft a hundred million kilometres from home). But even if they didn’t fire, it’s possible that the craft itself threw up enough dust to catch - the pellets were to make absolutely sure - so there’s a chance we’ll have a usable sample anyway.

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Read the rest of Tuesday video: Hayabusa’s fiery return

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It should be appearing on the site at some point today - in the meantime, have a listen to some of the others. There’s a lot good stuff on there.

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Antimatter

Every type of matter particle which exists - electrons, protons, neutrons and others - has a corresponding ‘antiparticle’. The antiparticles are very similar to their particle counterparts, having the same size and mass - in a way they’re very like a mirror-image version, and also have reversed electric charge. Antimatter seems very exotic to us, not least because of the well-known fact that a particle and its antiparticle brought together will annihilate each other and release a colossal amount of energy, making antimatter very unstable and impossible to keep sitting in a jar without special precautions.

But this exoticness isn’t really inherent to the antimatter: after all, antimatter people living on an antimatter planet wound find a blob of matter just as strange and dangerous as we find them. Even the naming is arbitrary: neither type is more ‘anti’ than the other, since there’s a complete symmetry between them.

But why, if antimatter is so natural and so naturally paired to matter, is it rare and exotic when ‘normal’ matter is everywhere? Why are the two not equally abundant?

That question is one of the most important ones facing physics today.

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Read the rest of Why is there stuff?

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A simulated galaxy undergoing ram stripping. The image is about a million light years top to bottom.

For example: what’s the most important property of the gas in determining the amount of stripping that goes on? Is it the density of the gas, or the speed at which the galaxy hits it? Then again, does the temperature of the gas have a bigger effect? To answer this question observationally we’d find lots of galaxies undergoing stripping, measure all the quantities we’re interested in, and look for a relationship. But it might not turn out to be as simple as all that. For instance, the gas tends to be hotter and denser in bigger clusters. So if we find a relationship between stripping and density, it could just be telling us about the cluster mass. Since cluster masses are often quite hard to measure accurately - and in fact we often measure them by looking at the gas temperature - sorting out which variables are affecting what can be tricky.

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Read the rest of Tuesday picture: a galaxy in a wind-tunnel

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Earth and Jupiter with their moon systems. Credit: NASA/JPL/Malin Space Science Systems.

…and Jupiter with three of his.

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Read the rest of Tuesday picture: two marbles

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