Thursday, December 23, 2010


The moon moves across the sky. We all know that. But you can't really tell by just looking.

At least most of the time.

But when the conditions are right, you can see the moon move. Like on the night of the total lunar eclipse.

Early on in the partial phase of the eclipse, the moon occulted a magnitude 6.7 star with a name only an astronomy geek could love, SAO 77647.

Now I was still setting up my camera gear at ingress, so I've got no shots, but I was shooting away at emergence. If you look really close at the bigafied version of the image above (click on any image to see a larger version) you'll see a tiny bump at the three o'clock position. (You might want to check the below images first, where the star is much more obvious.)

My friend Joe was observed both the start and end of the occultation. And he made a point of how he really got a sense of the moon's motion as he did. Most of the objects in the night sky are much too distant to show motion in real time. Only objects closer to home, those in our solar system, show any such motion.

More distant objects do show motion, but on the scale of decades or centuries. Not something obvious during a nights observing. The first two shots here were taken less than half a minute apart.

I had a similar experience watching Comet Lulin last year, as it moved past the field stars. Perhaps, like the star name, watching an occultation is something only an astronomy geek can get excited about. But I think that knowing something and then seeing it for yourself is really cool.


Ron a.k.a. Danudin said...

Thanks Teech!

Lené Gary said...

These are absolutely incredible, Steve! Thanks for sharing. :)

Anonymous said...

Beautiful shots, Steve. We were totally socked in here much to my 13-year-old son's chagrin.

MevetS said...

@ Ron: any time. :-)

@ Lené: My pleasure.

@ Julie: ah bummer. We stayed out all night, and stopped at a diner on the way home. A weather map shown on the TV had most of the continent clouded over. We were very lucky.