Bob Moler's Ephemeris Blog

Ephemeris for Monday, July 15th.  Today the sun will be up for 15 hours and 12 minutes, setting at 9:24.   The moon, at first quarter today, will set at 12:48 tomorrow morning.  Tomorrow the sun will rise at 6:12.

The moon this evening is very close to the bright star Spica.  It might take a pair of binoculars to spot it in the glare of the moon.  Spica will be just above left of the moon tonight.  For other spots on the earth the moon will actually pass in front of the star.  The event is called an occultation, from the word occult meaning hidden.  Simply put the moon will pass in front of or hide the star for up to an hour.  The chief beneficiary of this occultation is the state of Hawai’i.  Occultations are one of the best ways to measure the position, diameter and shape of distant asteroids and Kuiper belt objects that are too small to measure otherwise.  Satellites of these objects have also been discovered this way.

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

Addendum

Spica and the Moon at 10 p.m. on July 15, 2013. Created using Stellarium.

Path on the Earth where the occultation of Spica will be visible. Credit Astronomical Almanac Online.

The Astronomical Almanac Online ( http://asa.usno.navy.mil/) “is a joint publication of the U. S. Nautical Almanac Office, United States Naval Observatory (USNO), in the United States and Her Majesty’s Nautical Almanac Office (HMNAO), United Kingdom Hydrographic Office (UKHO), in the United Kingdom.”