OrbitLab

Planetary Distance Calculator

From AU to kilometers to light-minutes.

Distance (AU)

Distance (km)

149,597,870.7

Light travel time: 8.317 min

What you entered

Distance (AU): 1

1
km = AU × 149,597,870.7
1 × 149597870.7= 149597870.7 km
2
Light travel time
149597870.7 ÷ 299792.458 km/s ÷ 60= 8.3167 min

Result

Distance (km): 149,597,870.7

1 AU is 149,597,871 km — light takes 8.32 minutes to cross that distance.

Planetary distances in kilometres and light travel time

One astronomical unit is the Earth-Sun distance, 149,597,871 km. Light covers it in about 8.3 minutes.

Planet	Distance from Sun	Kilometres	Light travel time
Mercury	0.387 AU	57,894,376	3.22 minutes
Venus	0.723 AU	108,159,261	6.01 minutes
Earth	1 AU	149,597,871	8.32 minutes
Mars	1.524 AU	227,987,155	12.67 minutes
Jupiter	5.203 AU	778,357,721	43.27 minutes
Saturn	9.537 AU	1,426,714,893	79.32 minutes
Uranus	19.19 AU	2,870,783,139	159.60 minutes
Neptune	30.07 AU	4,498,407,972	250.08 minutes
Pluto	39.48 AU	5,906,123,935	328.35 minutes

These are average distances from the Sun, not distances from Earth, which change constantly as the planets orbit. The light travel times explain the communication delay with spacecraft: a command to a probe at Neptune takes over four hours to arrive.

The AU is astronomy's convenient yardstick

One astronomical unit (the Earth-Sun distance, about 149.6 million km) is used because solar-system distances in kilometers are unwieldy — Jupiter's ~5.2 AU is far easier to grasp than 778 million km.

Why light travel time matters for space missions

The same distance that converts to a light-travel-time delay is exactly why real-time control of Mars rovers is impossible — commands take several minutes each way, so rovers must operate with a degree of onboard autonomy.

Frequently asked questions

Mars is about 1.52 AU from the Sun — how far is that in kilometers and light-minutes?

1.52 AU × 149.6 million km = 227.4 million km. Light travel time = 227.4 million / 299,792 ≈ 758 seconds ≈ 12.6 minutes one way.

How is the planetary distance calculator different from the orbital period calculator?

This calculator converts AU to km and light travel time — pure unit conversion. The orbital period calculator uses Kepler's third law to find how long an orbit takes from that distance and the central body's mass.

Why do astronomers use AU instead of kilometers?

Solar system distances in km are unwieldy — Jupiter is 778 million km, Neptune is 4.5 billion km. In AU, those become 5.2 and 30 — far easier to compare and remember. AU also simplifies Kepler's third law calculations.