Thursday, February 23, 2012

Mercury and a 28-hour moon

Yesterday there was an aesthetically nice astronomical coincidence. Even better, I got to observe it from the comfort and convenience of the economics grad student lounge, which has a beautiful view towards the west from the 6th floor of a building up a hill in Berkeley. This means you can see all the way to the western horizon, so you can observe objects that fall right on the cusp of possibility, setting just after the sun itself.

Today Mercury and a 28-hour old moon coincided in this brief window. Mercury by itself is very difficult to observe: since it orbits close to the sun, you can only see it just after sunset or just before sunrise, and even then only rarely, when it's as far away from the sun as it ever appears to us (with the Earth and Mercury forming a right angle with the sun.) The last time I saw it definitively was in 2001 (although I can't say I've often tried; I'm more of a deep sky fan than a solar system buff...)

The same applies to extremely thin crescent moons. A goal of any lunar observer is to pick out the hairline crescent as soon as possible either before or after the new moon, when it passes directly between us and the sun and is momentarily invisible. 28 hours old is definitely not the youngest moon you can observe, but I think it's my personal record, and is definitely sufficiently strikingly beautiful.

So, some pictures:

Mercury and crescent moon side by side over bay, shortly after sunset (about half an hour)

moon through binocular eyepiece

Mercury and moon a little later, as it's getting dark

Jupiter (upper left), Venus (left of middle) and moon sliver (on horizon). Unfortunately Mercury didn't quite get picked up in this exposure, but you could still see it naked eye at the time.

3 comments:

Anthony said...

Informative post and great photos. PS. Some of my friends/fellow students while in grad school were Berkley (undergraduate) alums. Great school.

Anthony said...

Correction: "Berkeley"...they would probably kill me if they saw that error. Lol.

Vera L. te Velde said...

thanks Anthony :)