Author: Neal McBurnett
Posted: 2010-09-02 14:38:48-06:00
I love the cool picture of the Earth and moon from the Messenger spacecraft here.
But as an avid amateur astronomer, I'm trying to identify the stars. Not easy, since all the Messenger site gives is a date - no RA/Dec, constellation, etc.
In an effort to see where Messenger was on May 6, I found NASA's wonderful Solar System Simulator site:
I found the star field matches pretty closely if I plot it for the Earth at 8:00 UTC on the 6th:
Note that south is up in the image from Messenger. I figured that out because the moon, which is to the right of the Earth, was near 3rd quarter back then. So in the image which I included above I had to flip what I got from SSS by 180 degrees.
But I still have no idea exactly which way I'm facing and which stars those are. I figure they ought to be broadly speaking near Libra, since the sun from earth is in Aries, and Libra is in the opposite direction, and Messenger is near the sun.....
And that's all I have time for right now, other than suggesting to these two fine sites that they add information to the page about where we're looking.
If you've figured it out, leave a comment :)
| Update, before going to bed.... |
| Aha - I was right - it's in the constellation Libra! The two stars below the earth (actually North), halfway to the edge of the image, are 43 Librae and 41 Librae. Both about 5th magnitude, so you can see them on a good night. For a much richer sky field, see the 4-degree-wide image I saved from skyview (north is up this time): http://skyview.gsfc.nasa.gov/userimages/skv930353279680.html |
| [and hmm - comments seem to be broken....] |
Update Sept 4
By the way - the earth was at R.A. 15 37 27.02, Dec -20 47 26.1 and distance 1.22525823308655 AU from Messenger.
There is a discussion of this also at the APOD forum Starship Asterisk* http://bb.nightskylive.net/asterisk/viewtopic.php?f=9&t=20888&p=131323#p131217