How long is Mercury's orbit?

Mercury takes 88.0 days to go once round the Sun. It is travelling at 41.32 km/s at the moment — a speed that changes through the orbit, fastest at perihelion and slowest at aphelion.

What shape is Mercury's orbit?

An ellipse with the Sun at one focus, not at the centre. Its eccentricity is 0.2056, derived here from the perihelion and aphelion distances rather than quoted: 0.308 AU at closest and 0.467 AU at furthest, a difference of 23,815,897 km.

Where is Mercury in its orbit now?

0.444 AU from the Sun — 0.066 billion km — which is 86% of the way from its closest point to its furthest. It next reaches perihelion on 10 November 2026.

Mercury

Mercury's orbit

Once round the Sun every 88.0 days, on an ellipse drawn here from the ephemeris rather than from a formula.

Looking down on the plane of the ecliptic, traced from the ephemeris over one full orbit of 88 days. Earth’s orbit is the faint one, for scale. The Sun sits off the centre of the ellipse — that offset is the eccentricity, and it is why the two distances differ.

Orbital period: 88.0; days for one lap
Eccentricity: 0.2056; 0 would be a circle
Semi-major axis: 0.387; AU · the orbit's average radius
Speed now: 41.32; km/s, from the ephemeris

What is worth knowing about it

Mercury has the most eccentric orbit of the eight planets, and the fastest — it completes four laps in the time Earth takes one. Its perihelion also creeps forward by a fraction of a degree per century more than Newton allows, which was the first observational evidence for general relativity.

The shape of it

Mercury does not travel a circle. It comes as close as 0.308 AU (0.046 billion km) and goes as far as 0.467 AU (0.070 billion km) — aphelion is 1.52 times further out than perihelion, a swing of 23,815,897 km. At 0.206 this is one of the most elliptical orbits of any major body — far enough from a circle to see it in a drawing without being told.

Because the Sun sits at a focus rather than the centre, Mercury does not move at a constant speed either. It runs fastest when it is closest and slowest when it is furthest, sweeping equal areas in equal times — which is Kepler's second law, and is visible in the diagram above as the uneven spacing of a constant time step.

Where it is now

Today Mercury is 0.444 AU from the Sun, 86% of the way from perihelion to aphelion, travelling at 41.32 km/s. It reaches perihelion on 10 November 2026 at 0.308 AU.

Common questions

How long is Mercury's orbit?: Mercury takes 88.0 days to go once round the Sun. It is travelling at 41.32 km/s at the moment — a speed that changes through the orbit, fastest at perihelion and slowest at aphelion.
What shape is Mercury's orbit?: An ellipse with the Sun at one focus, not at the centre. Its eccentricity is 0.2056, derived here from the perihelion and aphelion distances rather than quoted: 0.308 AU at closest and 0.467 AU at furthest, a difference of 23,815,897 km.
Where is Mercury in its orbit now?: 0.444 AU from the Sun — 0.066 billion km — which is 86% of the way from its closest point to its furthest. It next reaches perihelion on 10 November 2026.

Positions from VSOP87 via Astronomy Engine, accurate to within one arcminute. The orbit above is traced by sampling a full period rather than drawn from elements, so the tilt and the off-centre Sun are the real ones. See Mercury’s distance from the Sun, Mercury right now, or watch the whole system move in the live simulation.