An Aristeia of Mars

Get ready for the opposition of Mars on Sunday May 22, and even better later.

Jupiter is still the brightest “star” in the evening sky, but as it goes down in the west Mars, now almost exactly its equal in brightness, climbs from the east.


Mars, along with Saturn, Antares, and the Moon, shows above the southeastern horizon.  It will be highest in the south at local midnight (called 1 AM by “Daylight-Saving Time”), and the exact moment of opposition will come a few hours later again.

The palely-red planet has been growing nearer and brighter since about April 17, when it went into retrograde motion (that is, when we started overtaking it).

I was going to let you see the two large pages on Mars in Astronomical Calendar 2016:
and then say that no more needs to be said, but I do have some more to say.

We could call a planet’s best-observable time – the time centered on its opposition – its aristeia.  In the Iliad, there are episodes in which one of the heroes, such as Diomedes (a Greek) or Hector (a Trojan), goes on a rampage, single-handedly routing the foe, and this was called his aristeia, “bestness.”  Even Ares (the Greek Mars), one of the gods sympathizing with the Trojan side, enters the battle and has a sort of abortive aristeia, but he is soon put out of action by his Greek-supporting sister Athena – “hateful Ares,” she calls him, because he loves nothing but conflict and blood.

Planet Mars’s aristeia of April-May-June 2016 is not quite his best, for three reasons.

First, he has to share it with Saturn, in the background and about to be at opposition next.

Earth passing Mars and Saturn

Oblique view of the planets moving along their orbits in May and June; Earth overtaking Mars on May 22 and Saturn on June 3.  Earth and Mars are exaggerated 400 times in size; Saturn, 100; the Sun, 5.  Stalks connect the planets to the ecliptic plane.  The red line indicates the vernal equinox direction (longitude 0).

Second, Mars is in the glare of the Moon, which is Full on May 21 at 21 Universal Time, and only 9 degrees away from Mars at the opposition.

Third: Mars will be nearer to us than at any opposition since 2005, but not as near as it was in 2003 or will be in 2018.  And unfortunately the near-in part of its orbit is tilted southward (in relation to our equatorial plane), which is why the planet is riding far below the celestial equator and not as high as we would like above the horizon.

But a pleasant feature of a Mars opposition in this part of its cycle is that it is near to Antares, the red “rival of Mars.”

Because Mars is on the inward-sloping part of its rather strongly elliptical orbit, the moment when it is nearest is not exactly at opposition but as much as 8 days and 10 hours later, on May 31 at 21 UT.

Mars when nearest

By then the Moon will be well out of the way.  Mars will at the same time of night be higher, because it is now in the evening sky.  It will be essentially as good in your telescope.  Actually, it will be an indiscernible 0.2 second wider, yet also an indiscernible 0.1 of a magnitude fainter; interestingly, the factor of nearness is slightly outweighed by the factor of phase, that is, of being full-face-on to us.

The first time I went to San Francisco, it was the scene of a great anti-war demonstration.  I remarked to someone I had met: “That’s Mars.  It’s nearly at opposition.”  Without asking what that meant, she turned around (we were in a crowd coming out of a stadium) and yelled: “People!  Mars is at opposition!”  This, you may well believe, stopped the war.


6 thoughts on “An Aristeia of Mars”

  1. In central Virginia, we finally seem to be getting relief from our month of cloudy, rainy weather, but despite a couple of clear nights, the seeing has not been good, so the views of Mars have not been great for us. The other night I could see the remnants of the north polar cap and some dark markings, probably Syrtis Major given its shape, but last night (May 24) I could only see some dark areas along the limb contrasted against an otherwise featureless orange disk. Either there’s a planet-wide sandstorm or my seeing was poor :) I’m guessing it was the seeing. Good luck to all in your Mars observing!

  2. Also, if you we able to stand on the western side of northern Mare Acidalium Saturn would be in basically at the same spot and height above the horizon as on Earth around 40º North Lat. Only by itself no full moon and now bright Mars since you would
    be standing on it..

    1. Good point. And on June 13 will come the heliocentric conjunction of Mars and Saturn, which is also the opposition of Saturn as seen from Mars.

      1. Hypothetical Martian skywatchers are appreciating their approaching Saturn opposition, all the more because they only get half as many as we Earthlings get.

  3. Rather than commiserating with poor Mars for needing to share the spotlight with Saturn, I feel sorry for Saturn, who is being upstaged by Mars. Usually this close to a Saturn opposition we would all be agog, but the ruddy nephew is hogging the limelight this year.

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