Four days ago, February 2^nd, we ‘celebrated'(?) Groundhog Day where in the Northern Hemisphere if the groundhog sees its shadow there will be 6 more weeks of winter. Coincidentally on Saturday February 6^th it is the spring equinox on the planet Mars as the planet transitions from its winter season to spring during its 684 Earth day orbit around the Sun. However there are no groundhogs on Mars! So there may be clear skies but given daily temperatures on the Martian surface to me it looks like spring time all the time, albeit rather cool!
   Seasons on Mars are marked by the planet’s heliocentric longitude coordinates using the position of Mars along its orbit around the Sun. Each seasonal start/ending point is 90 degrees apart, but because of its elliptical-shaped orbit each Martian season is of varying lengths.

   I’m not exactly sure why this particular date is used but by international agreement astronomers have selected April 11^th, 1955 as 0 degrees for year 1 of this Martian calendar. What this works out to is that on Saturday February 6^th, Earth time, it is the start of spring for year 36 using the aforementioned calendar system.

Year 35
0 degrees — Spring Equinox — March 23 2019
90 degrees — Summer solstice — October 08 2019
180 degrees — Fall Equinox — April 08 2020
270 degrees — Winter Solstice — September 02 2020

Year 36
0 degrees — Spring Equinox — February 06 2021
90 degrees — Summer solstice — August 25 2021
180 degrees — Fall Equinox — February 24 2022
270 degrees — Winter Solstice — July 21 2022

Learn a little (or a lot) more about the exploration of Mars at the NASA Explore the Moon to Mars website.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.


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