Look! Up in the Sky!

Posted by jns on 7 December 2008

All sorts of stuff has been going on up in the sky lately. There’s just so much to look at.

For instance, NASA sent word today (SpaceWeather for 6 December 2008) that the SOHO spacecraft, the orbiting solar observatory,^* has only hours ago taken this picture (like this one, which I’ve cropped quite a bit; full-sized source here) of a massive solar prominence. They also link to some additional amazingly beautiful photographs of the prominence taken by other people with solar telescopes: from Mark Walters of Four Crosses, Powys, Wales, UK; from Emiel Veldhuis of Zwolle, the Netherlands; from Robert Arnold of Isle of Skye, Scotland; from M. Ugro et al. of South Portland, Maine.

Now, you may remember the giant meteorite that made an appearance last week over British Columbia. There’s been another (a “superbolide”), this time in Colorado. From the same SpaceWeather page as above:

Astronomer Chris Peterson photographed the event using a dedicated all-sky meteor camera in the town of Guffey, near Colorado Springs.

“In seven years of operation, this is the brightest fireball I’ve ever recorded,” says Peterson. “I estimate the terminal explosion at magnitude -18, more than 100 times brighter than a full Moon.”

Here’s an animation of some of the photographs of the event.

Finally, more pretty pictures. There was some excitement earlier this week on Monday (1 December 2008), when there was, at sunset, a beautiful conjunction of Venus, Jupiter, and a crescent moon. We had clear, cold skies that evening and beautiful viewing of the event, which really was remarkably pretty. NASA has a “Conjunction Gallery” of very lovely photographs of the event submitted astronomy enthusiasts. Visit when you have some time to look and ooh and aah.
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^* About SOHO’s orbit, from the project page at NASA:

SOHO is in orbit between the Earth and the Sun. It is about 150,703,456 kilometers (92 million miles) from the Sun and only about 1,528,483 Kilometers (1 million miles) from the Earth (three times farther than the moon). This orbit is around a mathematical point between the Earth and the Sun known as the Lagrange point or the L1 point. The L1 point is a point of [gravitational] equilibrium between the Earth’s and Sun’s gravitational field, that is to say that the pull is equal from both the Sun and the Earth. The L1 point is a point of unstable equilibrium (like a bowl round side up with a marble balanced on it). As a result, we have to compensate for perturbations due to the pull of the planets and the Earth’s moon. Every few months we use a little fuel to fine tune our orbit and keep it from getting too far off track. This is known as “station keeping manoeuvres”

No spacecraft is actually orbiting at the L1 point. For SOHO there are two main reasons: the unstable orbit at the L1 point and facility of communication in a halo orbit. If SOHO was sitting directly at the L1 point, it would always be right in front of the Sun. The trouble is that the Sun is very noisy at radio wavelengths, which would make it very difficult to tune into the radio telemetry from the spacecraft. By putting it into a halo orbit, we can place it so that it’s always a few degrees away from the Sun, making radio reception much easier.