Mars retrograde: 10 January 2027 to 1 April 2027

What is actually happening

Mars never moves backwards. It orbits the Sun in the same direction as everything else, outside the Earth's orbit, once every 687 days, and it never slows down to do this.

What changes is where we are watching from, and this time we are the faster planet. The Earth laps Mars once every 780 days — about 26 months — overtaking it on the inside. For most of that time the two are far apart and Mars drifts eastward against the background sky like everything else. The reversal comes as we pass it: for two or three months our own motion outruns its, our line of sight to it swings the other way, and against the background sky Mars appears to slide backwards before picking up its usual course. The middle of the loop is opposition, when Mars stands opposite the Sun in our sky, closest to the Earth and at its brightest.

The two moments either end are called stations: the points where the apparent motion stops before reversing. They are what the table above gives, computed to the minute, because "late January" is not an answer anyone can use.

Mars's real apparent path over the period, plotted from its computed position each day. The marked points are the two stations. The loop is the whole phenomenon: a planet that never stopped, seen from a planet that did not stop either.

How often, and for how long

Once every 26 months or so, for anything from two months to nearly three: the two periods above run 81 and 80 days. The length varies more than Mercury's or Venus's because Mars's orbit is noticeably elliptical. The loop runs longest when we overtake it near the far point of its orbit, with the opposition falling in the northern winter, and shortest near the close point, in late summer. Mercury does the same thing three times a year for about three weeks, and Venus every nineteen months for about six weeks.

There is nothing unusual about any of it. Measured from the periods above, Mars spends about 11% of its time in apparent retrograde — roughly 81 days in every 26 months — and because the loop is centred on opposition, those are also the months it is closest and brightest. The weeks Mars is most conspicuous are the weeks it appears to move backwards.