Mercury

Mercury tonight from your location

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This panel computes tonight's position and rise and set times for Mercury in your browser, and it needs JavaScript to run. The rest of this page, including the calendars and event dates below, is fully readable without it. For a live all-sky view, open the Sky Map or Today in the Sky.

Everything is computed on your device. Tapping "Use my location" sends your coordinates once to a place-name service only to show your city's name. Times appear in your device's time zone.

Mercury at a glance

Physical data: NASA NSSDCA Mercury Fact Sheet (temperature extremes from NASA Science).

Morning star or evening star?

Because Mercury orbits closer to the Sun than Earth does, it never strays far from the Sun in our sky. It swings from one side of the Sun to the other, appearing as an evening star in the west after sunset, then as a morning star in the east before dawn. Each switch happens at a conjunction, when it passes nearly in front of or behind the Sun, and for a stretch around every conjunction date Mercury is too close to the Sun to see at all. Dates are in Universal Time.

How to see Mercury

Mercury only ever appears in twilight, and the viewing windows are the greatest elongations in the table above. An elongation is the angle between a planet and the Sun in our sky; because Mercury orbits inside Earth's orbit, that angle tops out between roughly 18 and 28 degrees, set by where the planet sits on its stretched path. At an evening elongation, look low above the western horizon as the sunset glow fades; at a morning one, low in the east before dawn. For northern observers, evening showings are best in spring and morning ones in autumn (reversed for southern observers), when the ecliptic, the line the Sun and planets follow across the sky, meets the horizon most steeply.

The single most important piece of equipment is a flat horizon: Mercury never climbs high before it sets or the sky brightens, so a treeline or bank of haze in the wrong direction hides it completely. Binoculars make the hunt far easier, provided you never raise them to sweep until the Sun is entirely below the horizon. Then scan the twilight for a single steady point of light; once found, Mercury is usually easy to hold with the naked eye.

Do not wait for a dark sky, because Mercury almost never appears in one; by the time twilight ends it has usually set, and at dawn the sky brightens around it. A small telescope shows a tiny disk, about 5 to 13 arcseconds across (tiny: the full Moon spans roughly 1,900 arcseconds), running through phases like a miniature Moon, from gibbous to a thin crescent as it swings near us. Surface detail is beyond backyard equipment, and the low altitude keeps the image churning; the photo on this page is a spacecraft view, not what the eyepiece shows.

Mercury's cycles

Mercury's synodic period of 115.88 days is the clock behind every apparition, the time it takes to lap Earth and line up with the Sun again. Mercury circles the Sun in 87.97 days, but Earth keeps moving too, so the meeting cycle runs about a month longer than the orbit itself. Our synodic vs sidereal lesson untangles the two clocks, and the Synodic Period Calculator derives the 115.88 days from the two orbits. Each lap brings one evening and one morning apparition, and at about three laps a year that means six or seven greatest elongations, more viewing windows than any other planet offers.

Mercury also holds one of the solar system's tidiest orbital locks, a true 3:2 spin-orbit resonance. It rotates once every 1,407.6 hours, about 59 days, exactly two thirds of its 88-day year, so it completes three spins for every two orbits, held in step by the Sun's tidal grip on its slightly lopsided body. A solar day on Mercury, sunrise to sunrise, therefore lasts about 176 Earth days, two full Mercury years. It is a cousin of the 1:1 lock that keeps one face of the Moon turned toward Earth, explained in our tidal locking lesson.

The same overtaking cycle makes Mercury the sky's most frequent backtracker. Around each inferior conjunction, the moment it passes between Earth and the Sun, Mercury appears to slide backward against the stars for a few weeks, so it turns retrograde three times in most years and occasionally four, more often than any other planet. Nothing about its orbit changes; it is pure perspective, and the retrograde lesson shows the geometry in motion. To find Mercury tonight, start with Today's Sky, or plot it over your own horizon with the Sky Map.

To see where these periods fit among everything else that repeats overhead, find the Mercury synodic period in the full list, sorted by length, on the Cycles page.

What's next for Mercury

These are the dates that shape each apparition: greatest elongations (the best viewing), and the conjunctions when Mercury switches between the morning and evening sky. Dates are in Universal Time.

Frequently asked questions

Why is Mercury so hard to see?

Mercury orbits inside Earth's orbit, only about 58 million km from the Sun on average, so from our vantage point it never appears more than about 28 degrees from the Sun in the sky. That keeps it trapped in twilight: it sets soon after the Sun in the evening, or rises only shortly before it in the morning, and it always sits low over the horizon, where haze and obstructions are worst. Brightness is not the problem; the challenge is timing and a clear horizon.

How long is a day on Mercury?

It depends which day you mean. Mercury rotates once on its axis every 1,407.6 hours, about 59 Earth days. But a solar day, noon to noon for someone standing on the surface, lasts about 176 Earth days, because the slow spin is locked in a 3:2 resonance with the fast 88-day orbit: three rotations for every two trips around the Sun. One Mercury solar day therefore spans two complete Mercury years.

Is Mercury the hottest planet?

No. Mercury's daytime side reaches roughly 430 degrees Celsius, but with almost no atmosphere to hold the heat, the night side plunges to about minus 180 degrees Celsius. Venus, wrapped in a thick carbon dioxide atmosphere, stays hotter than Mercury's daytime peak across its whole surface, day and night. Mercury's real record is the largest temperature swing of any planet in the solar system.

Does Mercury have any moons or rings?

No. Mercury has zero moons and no rings. It orbits deep in the Sun's gravity, where the zone in which a moon could circle Mercury stably is very small; anything wandering there tends to be pulled away by the Sun or lost. Of the eight planets, only Mercury and Venus travel with no moon at all.

How often is Mercury in retrograde?

About three times a year, and occasionally four. Every 115.88 days Mercury laps Earth on its faster inside orbit, and for a few weeks around that pass it appears to drift backward against the background stars before resuming its normal eastward march. It is a line-of-sight effect, like a slower car seeming to roll backward as you overtake it; Mercury itself never stops or reverses.

Is Mercury a morning star or an evening star right now?

Mercury is currently too close to the Sun to see. It passes between Earth and the Sun (inferior conjunction) on July 13, 2026, then emerges as a morning star, low in the east before dawn, with the best view at its greatest elongation on August 2, 2026. The apparition table on this page lists every switch for the next few years.

Keep exploring

• Sky Map: plot Mercury over your own horizon during a twilight window
• Retrograde Motion lesson: why Mercury backs up more often than any other planet
• Synodic vs Sidereal lesson: the 88-day orbit and the 116-day sky cycle, untangled
• Synodic Period Calculator: derive the Mercury-Earth meeting cycle yourself
• Venus: the other inside planet, and a far easier twilight target