Bob Moler's Ephemeris Blog

Ephemeris for Tuesday, February 19th.  The sun will rise at 7:36.  It’ll be up for 10 hours and 41 minutes, setting at 6:17.   The moon, 2 days past first quarter, will set at 4:01 tomorrow morning.

Last Friday we had what I’d call a hit and a miss.  The miss was the close passage of asteroid 2012 DA14 a rock maybe half the size of a football field.  We’ll know better once radar observation of the asteroid are processed. Up to then the size was calculated by its brightness and its supposed reflectance or albedo.  That last is the biggest variable.  The asteroid was traveling at a slight angle to the earth’s orbit and a bit slower than the earth.  It was crossing the earth’s orbit heading slightly northward, what astronomers call ascending node.  That’s why the asteroid appeared heading north from our point of view.  The meteoroid that exploded over Russia I think had a slight southerly trajectory.  We’ll find out when the orbit is reconstructed.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

The Bad Astronomer Phil Plait has the story of the Russian Meteor with lots of videos.

http://www.slate.com/blogs/bad_astronomy/2013/02/15/breaking_huge_meteor_explodes_over_russia.html

The Planetary Society Blog has more information including a Webcast available at:

http://www.planetary.org/blogs/mat-kaplan/20130218-2012-da14-planetcast-on-demand.html