This has been a most interesting year to follow Mars. If you’ve been monitoring the Red Planet since the start of 2025, you have no doubt noted the dramatic change in its brightness as well as the occasional interactions it has had with the moon, bright stars and other celestial objects.
Mars travels a little more than half of its orbit each Earth year, and thus has oppositions (that point in the sky where it appears directly opposite to the sun in the sky) every two years plus about 50 days (its “synodic period,” which is also the longest for any known planet). Prior to 2025, the last opposition of Mars was on Dec. 8, 2022; after 2025, the next will come on Feb. 19, 2027. It reached opposition this year on Jan. 16 and two nights earlier, on Jan. 14, a nearly full moon passed directly in front of Mars as seen from much of North America.
Mars is the most Earth-like planet of all known beyond our own, and it passed closest to Earth during the American morning of Jan. 12, just 3.5 days before opposition.
An “off year” for the Red Planet
But the 2025 apparition of Mars has been one of the poorer and more distant ones in the planet’s 15-to-17-year cycle of oppositions near and far. Just three months after opposition, Mars arrived at aphelion (farthest from the sun) in its eccentric orbit, so we came no closer than 59.7 million miles (96.1 million kilometers) to it last winter — some 5.3 light minutes away. Shining with a yellow-orange hue, it attained its peak brightness, gleaming at magnitude -1.3. That’s just a trifle fainter than Sirius, the brightest star in the sky.
Ever since Jan. 12, however, it has been receding from Earth, and consequently it has gradually been getting dimmer. So, we’re leaving it behind, and ever since Feb. 24, Mars has been traveling in prograde (eastward) motion — a long, straight line around the sky, becoming steadily farther away and smaller. Still, in spite of its fade-down, it continued to put on an eye-catching show during February and March with the “twin stars” of Gemini, Pollux and Castor as the brightest member of a prominent, albeit temporary, triangle.
And then, on the evening of May 4, Mars made a very close pass near the Beehive Star Cluster (M44), a very pretty sight as viewed through binoculars or a low-power, wide-field telescope.
And during the latter part of June, Mars will again make for a couple of eye-catching shows, teaming up first with a bright star and then, late this month, with Earth’s nearest neighbor in space.
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A close conjunction with Regulus
Mars now appears as nothing more than a featureless dot in most telescopes. But on Tuesday evening (June 17), it forms a wonderful naked-eye pairing with the thin, only slightly brighter star Regulus in the constellation of Leo the Lion. Observers in the Americas will see the planet and star 2 degrees apart or less from June 13 through June 20, and one degree or less apart June 15 through June 18.
For viewers, around 40 degrees north latitude, Regulus and Mars are side by side, only 1.5 degrees apart on June 14, and Mars is 45 arc minutes (three quarters of one degree) almost straight above Regulus on June 17. That will be the evening when they are closest together. Neither one is exceptionally bright; Regulus shines at magnitude +1.34 and Mars is at magnitude +1.41. But the fact that they will appear so near to each other and are so closely matched in brightness will make them appear to stand out in the early evening sky.
Look for them around 10 p.m. local daylight time, roughly one-quarter up in the western sky. In addition to their closeness to each other, look for the orange-gold of Mars and blue-white of Regulus to appear intensified by contrast to each other when they are so close together (as seen with the naked eye or binoculars).
Don’t miss this near miss!
On Sunday evening, June 29, a waxing crescent moon, 24% illuminated by the sun, will pass very close to Mars and make for a rather attractive sight, low in the western sky at dusk. The moon, moving around Earth in an easterly direction at roughly its own diameter each hour, will appear to pass just below the orange-gold planet. Even though North America will miss out on seeing the moon pass directly in front of Mars (called an “occultation”), Mars will attract attention as it slowly appears to glide above the moon.
The view of the moon occulting Mars will be restricted to parts of Ecuador and Peru.
After closest approach, the moon will move slowly away from Mars. Locations to the east (or to the right) of a line running roughly from central Texas through central Ontario will be in various stages of twilight at the moment that the moon and planet are closest together (called a “conjunction”).
To the west (or to the right) of that line, the sun will be above the horizon when the two are in conjunction, but will still appear relatively close as darkness falls. For places where the two are closest together within an hour or less after sunset, you’ll probably initially need binoculars to pick Mars out against the bright twilight sky.
Once the sky has sufficiently darkened, however, Mars will be relatively easy to see. For most locations, the upper limb of the moon will skim to within about 20 arc minutes (one-third of a degree) of Mars. For places across the northern U.S. and Canada, the gap between the two will be a bit larger, while across the southern U.S. and the Caribbean, the gap will be a bit smaller.
The table below (calculated exclusively for Space.com by Joe Rao) provides the specific details for 15 selected cities in the U.S. and Canada.
The table gives civil times (all p.m.) of Mars’ closest approach to the edge of the moon’s upper limb. Separation between Mars and the moon’s upper edge is given in terms of minutes of arc (the apparent width of the moon on June 29 is 31 arc minutes), and the percentage of the apparent width of the moon. A value of 0.48, for example, is equal to 48% of the moon’s width (or fractionally, slightly less than one-half).
Examples: from Miami, closest approach between Mars and the moon is at 10:13 p.m. EDT. Separation is 15 arc minutes or 0.48, which is just under one-half of a moon’s width from Mars to the upper edge of the moon. From New York, closest approach is at 9:48 p.m. EDT, the separation is listed at 23 arc minutes or 0.74, which means that 74% of the moon’s width will separate Mars from the moon’s upper edge.
Where do we go from here?
After its rendezvous with the moon, Mars will continue to press on to the east. In the weeks and months that follow, Mars will continue to be a fixture in the evening sky, but will continue to recede from Earth and consequently will get fainter, diminishing to the rank of second magnitude.
Passing north of Spica on Sept. 13 and Mercury on Oct. 19, Mars will be getting progressively lower in the sky — more southerly and nearer to the sunset. When it finally fades into the evening twilight glow of early November, it will be on the far side of the sun, some 225 million miles (362 million km) from Earth and just 1/13 as bright as it was in mid-January. It will finally end its run as an evening object when it will be at conjunction with the sun next year, on Jan. 9.
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky and Telescope and other publications.
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