Bob Moler's Ephemeris Blog

Ephemeris for Tuesday, September 21st.*  The sun will rise at 7:28.  It’ll be up for 12 hours and 13 minutes, setting at 7:41.   The moon, 2 days before full, will set at 6:49 tomorrow morning.

The planet Mercury is a mysterious place.  It is the closest planet to the sun.  It’s really close now because it’s at its closest part of the elliptical orbit of the sun.  Mercury’s distance from the sun today is 28.6 million miles, and it’s 91.2 million miles from us.  Being the closest planet from the sun has made it very difficult to study with a telescope.  It’s always close to the horizon where the atmosphere raises havoc with the image, and is never visible out of twilight, at least for observers north of the earth’s equator.  It’s a hard planet to get to as seen by the MESSENGER’s long travel time of nearly seven years.  That’s near an end.  In six months MESSENGER is to enter orbit of Mercury.  We’ll get exquisite images and data from this elusive planet.

*Times are for the Grand Traverse Area of Northern Michigan, USA.