Categories: "Science"

International Year of Astronomy

The IAU designated 2009 the year of astronomy. So this year I'll be trying to post more astronomy related goodness. With tools like the WorldWide Telescope the astronomical community can really try and spark people's curiosity about the universe around them. And hell maybe we could try and make a dent against the seemingly unstoppable encroachment of light pollution while we're at it, the skies should be for everyone to enjoy, regardless of if you live in a remote village in India or central London.

So let's start things off with a gorgeous image of an aurora (aka the northern lights) on Saturn.

Why do stars have a cross shape through them?

I've been following HST advent images the Boston Globe have been running over the last month, and reading the comments along the way.

I was shocked at the amount of nonsense attributing the universe to a supernatural deity of some kind, around half of what was posted was along these lines. I’m tempted to bring out the Flying Spaghetti Monster, and preach to all how the universe was touched by his noodly appendage.

Anyway aside from the nonsense there were several interesting comments, one of which asked:

I was once told that the cross shape (like the above image) that you see surrounding stars when you look up at the sky at night is actually just the result of scratches in our corneas, and that they don't make that '+' sign thing at all.

Yet looking at your beautiful images, most stars do in fact have the cross running through them. Can you explain? I'm most curious because I don't see any reason for that phenomenon to occur.

Stars don't make a cross shape when looked at with the naked eye - they should appear as points of light. If they're making funny shapes you should probably see an optician.

The cross shape in these images comes about because of the type of telescope used. Most people are familiar with the idea of a refracting telescope - a long tube with a lens at the front, and one at the end. These telescopes typically aren't used for astronomy because of their length, usually they're around fifteen times longer than they are wide - the width, or aperture of a telescope (or the lens or mirror of the telescope) is very important for astronomical work as we need to capture as much light as possible.

Astronomers typically use what's called a reflecting telescope. Instead of using a lens at the front of the telescope to gather light, it uses a mirror at the bottom which then reflects the light to a secondary mirror closer to the front of the telescope which sends it either out of the side or back down the tube to an eyepiece or camera.

The advantage with this design is the tube can be much shorter and easier to manage. Seven times longer than the width is a fairly common figure, and some types of reflectors are even shorter still. Reflectors are also cheaper to manufacture for a given aperture. Meaning we can gather more light for less money, when you're trying to get every last photon to reach your eye or camera, the larger the primary mirror or objective lens the better.

There are some drawbacks however. These cross shapes through bright objects are one of them. These are caused by the support struts (3 are shown in the diagram above, but usually there are four, like with the HST) which hold the secondary mirror into place. Light passing close to them diffract slightly, this creates the cross shaped pattern around the brighter stars.

Words of wisdom from Mr Branson

It's not every day we encounter such brilliance, I think everyone should take the time to read these words of wisdom from Richard Branson.

Hospitals are there to cure people - they are not to kill people.

Incredible. How on Earth did we manage to get along before this guy came along and shared his intellect with us?

He accuses politicians of tinkering with infection controls in hospitals, largely in relation to strains of staphylococcus aureus that have become resistant to a large group of antibiotics, while he himself is doing the same tinkering suggesting all hospital staff be screened for MRSA.

What he, and a great deal of other people don't seem to be able to grasp these efforts can only be temporary. The only solution to permanently deal with this is increase the number of people going into science, and to increase research spending, be it public or private. It is also necessary to tackle religion through solid science education, especially in the United States where it no doubt acts like a colossal break on scientific development - especially in evolution, genetics and going forward bio-engineering, all areas that will become critical in dealing with this going forward.

Probably the most worrying though is that the government accepts advice from non-experts like Richard Branson.

Venus and the Moon

The forecast was predicting heavy cloud cover after dark yesterday, but in the afternoon we had a clear spell. I used this opportunity to capture Venus and the Moon before the occultation. The following was taken at 15:34 UTC, a few minutes before the Moon moved in front of Venus.

As predicted the cloud covered the rest of the occulation.

Images of exoplanets around Sun-like stars!

You don't get many days like this. The first image of an exoplanet around a Sun-like star has been released. Previously we had only visually detected a 5 mass Jupiter exoplanet around a brown dwarf star. Brown dwarf stars are too small to undergo any nuclear fusion, and as such they just dimly glow from their original formation. This makes planets far easier to detect around them as they put out millions of times less light, which normally hides any planets. This however is a proper star.

Yup that tiny little dot is a planet estimated to be around the same mass as Jupiter.

The planet Fomalhaut b orbits Fomalhaut (aka Alpha Piscis Austrini) once every 872 years, it is pretty far out. The star itself is not easily visible from the UK, it hugs the horizon even at this time of year when its at its highest point.

In this image the star is blocked out (artificially eclipsed if you will), and the remaining starlight is then subtracted from the image by using a template of another star. The dust ring around it is actually real, as is the planet, the lines radiating from the central star are artifacts.

And that's not all, we've also got the first image of multiple planets orbiting the star HR 8799, this time taken in infrared, which reduces the contrast differences between the star and the planet. Again the light from the star had to be blocked out. This system is only about 60 million years old which worked in our favour for detecting these planets as they're still warm from their original formation and as such release much more infrared light than normal.

New build of WorldWide Telescope released

Have just been throwing my must-have applications onto my Windows 7 system and came across a nice surprise. There's a new build of WorldWide Telescope available. Here's the official blurb for those who haven't already tried it out:

Immerse yourself in a seamless beautiful environment.

WorldWide Telescope (WWT) enables your computer to function as a virtual telescope, bringing together imagery from the best ground and space-based telescopes in the world. Experience narrated guided tours from astronomers and educators featuring interesting places in the sky

I notice the website has had a bit of an overhaul, that there's several new sky surveys available, that it now has a 3D fly-around mode for viewing the Solar System and the Milky Way, similar to Celestia, and according to the little tip of the day box that popped up it now supports Xbox 360 controllers, but as it's gone 4 in the morning I'll have to wait until tomorrow and see if its got better support for 120 DPI systems and see if I can see anything else that's new.

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