Mars at Opposition

Magnitude: -2.6
Apparent size:22.5 arc-sec.
Diameter:6792 km.
Distance:0.41 AU (3.46 light min).

Mars will be at opposition this year on 14th October but its closest orbital approach was actually on 7th October. I took this image midway between the two, on 10th October.

The synodic period of Mars (the time between two oppositions) is the longest of all the seven celestial planets. How long is the synodic period?

The Earth (orbital period 365 days), overtakes Mars (orbital period 687 days) and as a result, the synodic period is 780 days.

Surface features visible in this image include the white southern polar cap.

The image is the result of extracting and stacking the best 20% of frames from a five hundred frame video.

One of the advantages of opposition is that future astronauts on Mars could ask a question from their flight controller on Earth and only have to wait about seven minutes to get a response!

Telescope Details

SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Field flattener; 2x Powermate.
SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Imaging camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).
Software: EQMOD, Cartes du Ciel, PHD2, SharpCap, Autostackert, Gimp.
Observatory location: 34° South.

See annotated image at

The Seven Best Southern Sky Objects


  1. Your image is excellent. It joins the thousands of others posted by astronomers worldwide. The culmination of opportunity and technology has produced a great show for the planet.

    I was out viewing Mars that night, too. It was strictly by eyepiece and at about 75x. I could make out subtle variation of the surface. But, no details like your image shows. I later looked around for other things to view. I was surprised how few stars were visible. We had been covered by another haze layer from fires to our west. Hoping it will improve for those suffering from the fires.

    Liked by 3 people

    1. Thanks. Yes, I am conscious that many are taking the opportunity to record the occasion. Whilst I’ve stepped back a bit from social media, it’s great to see so many great images of our neighbour. The next few oppositions won’t be as close.

      Sorry to read that you are getting smoke haze, the fires must still be quite bad.


    1. …and forgot to mention, by the time Mars has humans on or near it, hopefully Star Trek’s vision of “subspace communication” will be a reality, and there will be no transmission delay, especially for a planet so close.

      Liked by 2 people

      1. Thanks. I bet it’s cold at the South Pole.

        Instantaneous transmission would very handy if it were possible. Especially so when Mars is at conjunction, where the time lapse would be more like half an hour!

        Robots seem to handle the delay quite well (Voyager 1 takes nearly 42 hours, two-way) but humans in space may find it somewhat unbearable!

        Liked by 1 person

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