Mars and Jupiter Conjunctions

About this pairing

Jupiter, near magnitude minus 2, is the brighter of the two, with Mars varying a great deal as its distance from Earth changes. When Mars is near one of its close approaches it can rival Jupiter for a while, making a Mars-Jupiter conjunction especially eye-catching. On average the two line up about every 2.2 years.

Both are outer planets that travel all the way around the zodiac, so unlike the Venus pairings these conjunctions can fall anywhere in the sky, including high overhead in the middle of the night. The table shows where each one lands and how closely the two approach.

For the rhythm behind these meetings, the average time between alignments of any two planets, see the Synodic-Period Calculator.

Watching this pair

Unlike the Venus pairings, a Mars-Jupiter meeting owes nothing to twilight, which makes it the most comfortable bright-pair conjunction to observe. You can catch it high in a fully dark sky, sometimes near midnight, with no race against the sunrise and no low, murky horizon to squint through.

It is also the pairing with a genuine contest in it. Jupiter holds steady near magnitude minus 2 while Mars swings enormously with its distance from Earth, a dim ember most years yet a match for Jupiter when a meeting falls near one of its close approaches. Those close-approach years are the ones worth timing from the table above.

Photographing Mars and Jupiter

Of all the bright pairings, this is the one you can photograph at leisure. With no twilight deadline to beat, you can work deliberately: set a camera on a tripod, choose a modest telephoto that frames the pair with a little room to spare, and take a series of frames rather than one rushed shot. A cable release or the camera's two-second timer keeps each frame sharp.

The exposures are straightforward: Jupiter is steady near magnitude minus 2 and Mars a smaller amber point beside it, both easily held in a fraction of a second to a couple of seconds at a low ISO. The color contrast, white Jupiter against orange Mars, is the picture, and it reads best when a meeting falls near one of Mars's close approaches, when the red planet is at its brightest. A short lens that takes in some landscape suits the wider meetings; a longer one isolates the pair when they draw especially tight.

Because the pair is up for hours in a dark sky, it also rewards a patient sequence. A photograph on each clear night through the weeks around the meeting, framed the same way every time, records the two planets sliding toward each other, touching at closest approach and drawing apart again, with the fixed background stars holding still behind them. Stacked into a simple animation or laid side by side, that run of frames turns an abstract idea, that the planets wander while the stars do not, into something you can watch happen. No tracking mount is needed for a project like this, only a tripod, a consistent framing and a little persistence with the weather.

The two-year rhythm, and the years Mars competes

Mars and Jupiter line up about every 2.2 years, and that interval is essentially Jupiter's slow drift plus the time Mars needs to catch it again. Jupiter takes almost twelve years to circle the zodiac, so from one meeting to the next it has moved only a little, and Mars, running its own orbit in under two years, does most of the chasing. The exact gaps wander because both planets speed up and slow down against the stars through their yearly retrograde loops.

What makes a given meeting memorable is where Mars stands in its cycle of approaches to Earth. Most years Mars is a dim ember and Jupiter dominates the pair, but when a conjunction lands near a Mars opposition the red planet can climb toward magnitude minus 3, brighter than Jupiter usually appears, and the sky carries two rival beacons of almost equal rank. Those are the meetings worth marking, and the live table above shows when the next ones fall.

Occasionally the geometry throws in a bonus. If a conjunction falls while both planets are near their retrograde loops, Mars can pass Jupiter, reverse and pass it again, then cross a third time, a triple conjunction spread over weeks rather than the single clean meeting of a typical year. These are uncommon for this pair but reward anyone watching night to night, as the gap between the two visibly opens, closes and opens again.