How far is Neptune from the Sun?

Today, 10 October 2026, Neptune is 4,469,746,509 km from the Sun — 4.47 billion kilometres, or 29.88 astronomical units. That figure changes constantly: the orbit is an ellipse, so Neptune is closer at one end than the other.

What is Neptune's average distance from the Sun?

30.07 AU — 4.50 billion km. This is the semi-major axis, which is the number most references quote as "the" distance. It is an average, and Neptune is actually at it only twice per orbit.

What are Neptune's closest and furthest distances?

Closest (perihelion) 29.81 AU or 4.46 billion km, next on 11 September 2042. Furthest (aphelion) 30.34 AU or 4.54 billion km, next on 16 November 2125. The difference between them is 79,759,180 km.

How long does sunlight take to reach Neptune?

4.14 hours at today's distance. Light from the Sun reaches Earth in about 8 minutes 20 seconds, so sunlight arrives at Neptune roughly 29.9 times later than it reaches us.

Neptune

Neptune's distance from the Sun

Not the average everyone quotes — the figure for today, and the two extremes it swings between.

Right now

4.47 billion km

4,469,746,509 km · 29.88 AU · sunlight takes 4.14 hours to get there

Computed 10 October 2026 and rebuilt through the day.

Closest to the Sun: 29.81 AU; 4.46 bn km · 11 September 2042
Furthest from the Sun: 30.34 AU; 4.54 bn km · 16 November 2125
Average: 30.07 AU; the figure most tables give
Orbital speed: 5.47 km/s; right now, from the ephemeris

Why there is no single answer

Neptune’s orbit is an ellipse with the Sun at one focus rather than at the centre, so the distance changes continuously. Over one orbit it swings by 79,759,180 km — aphelion is 1.02 times further out than perihelion. At 0.0089 its orbit is very nearly a circle — draw it to scale and the difference from one would be thinner than the line.

That is why the number in an encyclopedia and the number here differ. Theirs is the semi-major axis, an average over the whole orbit; this one is where Neptune is today. Both are correct, and they answer different questions.

Looking down on the plane of the ecliptic, traced from the ephemeris over one full orbit of 165 years. Uranus’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.

Where it is heading

Neptune reaches perihelion — its closest approach to the Sun — on 11 September 2042, in 16 years, at 29.81 AU. It is currently 13% of the way from perihelion to aphelion, moving at 5.47 km/s.

Distance from Earth is a different question again, and a more variable one: today it is 28.91 AU, and it changes as both planets move. Neptune right now carries that figure.

Common questions

How far is Neptune from the Sun?: Today, 10 October 2026, Neptune is 4,469,746,509 km from the Sun — 4.47 billion kilometres, or 29.88 astronomical units. That figure changes constantly: the orbit is an ellipse, so Neptune is closer at one end than the other.
What is Neptune's average distance from the Sun?: 30.07 AU — 4.50 billion km. This is the semi-major axis, which is the number most references quote as "the" distance. It is an average, and Neptune is actually at it only twice per orbit.
What are Neptune's closest and furthest distances?: Closest (perihelion) 29.81 AU or 4.46 billion km, next on 11 September 2042. Furthest (aphelion) 30.34 AU or 4.54 billion km, next on 16 November 2125. The difference between them is 79,759,180 km.
How long does sunlight take to reach Neptune?: 4.14 hours at today's distance. Light from the Sun reaches Earth in about 8 minutes 20 seconds, so sunlight arrives at Neptune roughly 29.9 times later than it reaches us.

Positions from VSOP87 via Astronomy Engine, accurate to within one arcminute. Perihelion and aphelion are found by search rather than taken from a table, which is why the dates are exact and why the extremes differ slightly from one orbit to the next — the other planets pull on this one. See Neptune’s orbit, Neptune right now, or watch it move in the live simulation.