Home > Ephemeris Program, Mars, Observing > 02/25/2014 – Ephemeris – Mars starts its retrograde motion this weekend

02/25/2014 – Ephemeris – Mars starts its retrograde motion this weekend

February 25, 2014

Ephemeris for Tuesday, February 25th.  The sun will rise at 7:26.  It’ll be up for 10 hours and 58 minutes, setting at 6:24.   The moon, 3 days past last quarter, will rise at 5:15 tomorrow morning.

The planet Mars, which rises about 10:30 p.m. and is near the star Spica, is slowing its eastward motion as the Earth approaches it.  Mars will stop and appear to reverse course on Saturday March 1st.  It will begin what astronomers call retrograde motion.  This westward motion will continue past Mars’ opposition with the sun on April 8th, and its closest approach to the Earth on April 14th.  Mars retrograde motion will end on May 21st when Mars will resume its prograde or eastward motion.  The ancient Greeks especially had a problem with this because they believed that celestial bodies traveled in uniform circular motion.   They added a circle on the planet’s main circle called an epicycle to kind of solve the problem.  The problem was solved centuries later by Copernicus who made the earth another planet and Kepler who made the planet orbits elliptical.

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

Addendum

Retrograde trails

The trails of Mars and three asteroids from December 2013 to August 2014. Created using Stellarium.

Vesta and Ceres are going retrograde at the same time as Mars.  The Dawn spacecraft traveling between Vesta to Ceres is about half way in between them.  The other trail, not exhibiting retrograde is that of the small asteroid 2012 DA14 whose claim to fame is that it passed inside the ring  of geosynchronous satellites on February 15, 2013.  It was completely upstaged a few hours earlier by the meteor that exploded over Chelyabinsk, Russia.  It looks like the orbital trail shown for 2012 DA14 has not been updated.  As the result of the encounter with Earth that day the asteroid’s orbit was altered.  2012 DA14 is a provisional designation based on the year, half month and order of discovery.  It’s permanent designation with a name is 367943 Duende.  The name of the asteroid is usually up to the discoverer with the approval of the International Astronomical Union (IAU).  It is the 367,943rd asteroid whose orbital elements are known.  BTW Ceres is 1 Ceres, and Vesta is 4 Vesta.  Though the 4th asteroid found, Vesta is the brightest, at the very limit of naked eye visibility.

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