It’s Spring on Mars

   Thursday June 18^th at 13 UT (8 am CDT) is the spring equinox on the planet Mars as the planet transitions from winter during its 684 Earth day orbit around the Sun.
   Seasons on Mars are marked by the planet’s heliocentric longitude coordinates using the position of Mars along its orbit around the Sun. At the Martian spring equinox Mars is at 0^o longitude. Each seasonal start/ending point is 90 degrees apart, but because of its elliptical-shaped orbit each Martian season is of varying lengths. Mars is at its greatest distance from the Sun, aphelion, before it reaches the Martian summer solstice when Mars is at 70^o longitude. Perihelion, its closest to the Sun, is when Mars is at 250^o longitude.
   I’m not exactly sure why this particular date is used but by international agreement astronomers have selected 11 April, 1955 as 0 degrees for year 1 of this Martian calendar. What this means is that Thursday June 18^th at 13 UT (8 am CDT) Earth time, is the start of spring for year 33 using the Earth-designed Martian calendar system.

   Mars is currently at solar conjunction, on the opposite side of the Sun, and will not be visible until later next month, July.

Year 32
0 degrees — Spring Equinox — Jul 31 2013
90 degrees — Summer solstice — Feb 14 2014
180 degrees — Fall Equinox — Aug 17 2014
270 degrees — Winter Solstice — Jan 11 2015
Year 33
0 degrees — Spring Equinox — Jun 18 2015
90 degrees — Summer solstice — Jan 03 2016
180 degrees — Fall Equinox — Jul 04 2016
270 degrees — Winter Solstice — Nov 28 2016
Year 34
0 degrees — Spring Equinox — May 05 2017
90 degrees — Summer solstice — Nov 20 2017
180 degrees — Fall Equinox — May 22 2018
270 degrees — Winter Solstice — Oct 16 2018

Learn a little (or a lot) more about Mars at the NASA/JPL Mars Curiosity mission web site.

Here is approximately 3 minutes worth of Mars from the Orbit performance.

   
   
   

   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Filed under: Astronomy, Mars, Observing, Planets, seasons Tagged: astronomy, mars, orbit around the sun, planet mars, planets, seasons, seasons on mars, spring equinox, spring on mars, summer solstice, sun