Home > Observing, Occultation, The Moon, Venus > Venus Occultation December 7, 2015 from Northern Michigan

Venus Occultation December 7, 2015 from Northern Michigan

December 5, 2015

What is an occultation?  An occultation is when one nearer celestial body covers  or hides another, more distant body.  The word occultation comes from occult which simply means hidden.  No black magic is involved.

The occultation of Venus will occur on December 7, from 12:21 p.m. to 1:27 p.m. for the Grand Traverse Area, give or take a few minutes either way. The exact time depends on your location.  This event would be a great sight if it occurred in the early morning skies before sunrise.  Unfortunately it’s centered on 1 p.m.  Venus and the Moon are visible in the daytime with a telescope and even binoculars, but are difficult to find.  The Moon and Venus do make a beautiful sight in the morning in the 5 to 7 a.m. hours.

Venus Disappearance.

Disappearance of Venus at 12:20 p.m. Created using Cartes du Ciel (Sky Charts).

The trick to viewing this event is even finding the Moon or Venus.  One could set up a telescope with tracking ability to track Venus throughout the morning. Unless you have a telescope Go To mount and can track the Moon, track Venus instead.  The Moon moves about its own diameter with respect to the stars in an hour, so it will have to be constantly adjusted to keep pointed at the Moon. Actually Venus has a higher surface brightness than the Moon, so it should be easier to track, especially if the sky is hazy and the Moon isn’t visible.

Venus Reappearance.

Disappearance of Venus at 1:27 p.m. Created using Cartes du Ciel (Sky Charts).

Unlike a stellar occultation Venus will disappear over several seconds.  A telescope capable to seeing Venus’ gibbous phase will see the bright edge of the Moon actually pass in front it.  Venus will emerge from the Moon’s dark side which will be invisible.  So Venus will slowly reappear next to the crescent Moon.  Hoping for clear skies, and good luck.
If you are not located near Traverse City, you can use my technique to estimate the occultation times.  I used Cartes du Ciel the free software found on the Internet at http://www.ap-i.net/skychart/en/start.  Make sure that the program is set for topocentric positions under Setup/Solar System.  And you have entered your position under Setup/Observatory.  You can find your location in Google Earth.
You can also use Stellarium (http://stellarium.org).  Just make sure the Moon is normal sized.
In both programs you can lock the Moon or Aldebaran in the center of the screen Pick a time in advance of the occultation and using the set time window walk the star towards the Moon, mark the time.  Then walk the star out from the Moon and record the reappearance time.  That’s it.
This should work with other planetarium programs too.


Animation of the occultation. Created using Cartes du Ciel (Sky Charts) and GIMP.

For better accuracy go to the International Occultation Timing Association (IOTA) website.  Download and install their Occult4 program for Windows computers.  Follow the instructions.  When I ran the program for my location, the location I use for Interlochen/Traverse City (Since I live approximately half-way between the two).  I got results within a half-minute of the IOTA Occult4 program results.  So the approximation method using planetarium programs is valid.

Sky at occultation start

Sun and Moon’s positions at the start of the occultation from northern Michigan. Note the Moon and Venus will be invisible to the naked eye. Created using Stellarium.

Sky at occultation end

Sun and Moon’s positions at the end of the occultation from northern Michigan. Note the Moon and Venus will be invisible to the naked eye. Created using Stellarium.

When I made up the above images I really thought there would be snow on the ground by now.  But what little we had has come and gone.

Occultation Map

Occultation of Venus Visibility Map for North America. Credit: Astronomical Almanac Online -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.

  1. richard kuschell
    December 6, 2015 at 7:51 pm

    Where in travere city the sky should I look for the moon?

  2. December 6, 2015 at 9:14 pm

    At the start of the occultation Venus and the Moon will be about 223 degrees azimuth, 2 degrees east of due southwest and 24 degrees altitude. At the end Venus and the Moon will be about 237 degrees azimuth and 16 degrees altitude. That’s according to the two sky images in the post that show the supposed sky with snowy trees in the above post.

  1. December 7, 2015 at 12:03 am
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