How far is Saturn from Earth?
Saturn is between about 1.2 billion km (750 million miles) and 1.66 billion km (1.03 billion miles) from Earth, depending on where the two planets are in their orbits. At its closest, around opposition, light from Saturn takes about 67 minutes to reach us; at its farthest, when Saturn is behind the Sun, about 92 minutes. Averaged over time, the distance is close to Saturn's distance from the Sun, about 1.43 billion km.
Contents
Why the Earth–Saturn distance changes
Both planets orbit the Sun, at very different distances and speeds. Earth circles at 1 astronomical unit (AU, about 149.6 million km) in one year; Saturn moves along a much larger orbit of 9.54 AU in 29.46 years. The gap between them therefore depends on two things.
The first is their relative position. When Earth passes between the Sun and Saturn, an alignment called opposition, the two planets are on the same side of the Sun and the distance is at its smallest: roughly Saturn's distance from the Sun minus 1 AU. About six months later, at conjunction, Saturn lies on the far side of the Sun and the distance is roughly Saturn's solar distance plus 1 AU. This cycle repeats every 378 days, Saturn's synodic period, which is why oppositions come about two weeks later each year.
The second is Saturn's own orbit. With an eccentricity of 0.054, Saturn's distance from the Sun varies between about 1.35 and 1.51 billion km over its 29.5-year orbit. Oppositions that happen while Saturn is near perihelion bring it closest, about 8.0 AU or 1.2 billion km; those near aphelion are about 1 AU more distant. Saturn last passed aphelion in 2018 and will reach perihelion around 2032, so successive oppositions through the late 2020s and early 2030s bring the planet slightly closer each time. The opposition dates page lists them.
| Configuration | Approximate distance | Light time |
|---|---|---|
| Opposition near perihelion | 8.0 AU, 1.20 billion km | about 67 min |
| Opposition near aphelion | 9.0 AU, 1.35 billion km | about 75 min |
| Conjunction near perihelion | 10.0 AU, 1.50 billion km | about 83 min |
| Conjunction near aphelion | 11.1 AU, 1.66 billion km | about 92 min |
Light time and talking to spacecraft
Light travels about 300,000 km per second, so even the minimum distance means more than an hour of delay. The Saturn we see in the sky is the Saturn of over an hour earlier, and any spacecraft there is effectively on its own. Commands sent to Cassini took well over an hour to arrive and the confirmation the same again to return, so every manoeuvre, from orbit insertion in 2004 to the final plunge in 2017, was preprogrammed. When Cassini's signal stopped on 15 September 2017, the spacecraft had already been destroyed in Saturn's atmosphere more than 80 minutes before engineers saw the carrier wave vanish. See Cassini's Grand Finale.
Radio signals also weaken with the square of distance. Cassini's 20-watt transmitter reached Earth with a power measured in billionths of a billionth of a watt, which is why NASA's Deep Space Network relies on dishes up to 70 metres across.
How long does it take to get to Saturn?
No spacecraft flies straight to Saturn. Launching directly would demand an enormous rocket, so missions borrow speed from other planets through gravity assists, and the flight time depends on whether the probe merely flies past or must slow down to enter orbit.
| Mission | Launch | Arrival at Saturn | Flight time | Route |
|---|---|---|---|---|
| Pioneer 11 | April 1973 | 1 Sept 1979 (flyby) | about 6 years 5 months | Jupiter flyby 1974 |
| Voyager 1 | Sept 1977 | 12 Nov 1980 (flyby) | about 3 years 2 months | Jupiter flyby 1979 |
| Voyager 2 | Aug 1977 | Aug 1981 (flyby) | about 4 years | Jupiter flyby 1979 |
| Cassini | 15 Oct 1997 | 1 July 2004 (orbit) | about 6 years 8 months | Venus twice, Earth, Jupiter |
Voyager 1 holds the record for a visit, but it flew past at high speed. Cassini, much heavier and needing to brake into orbit, took a longer path with four gravity assists. NASA's New Horizons, the fastest probe ever launched from Earth, crossed the distance of Saturn's orbit in mid-2008, about two and a half years after launch, though Saturn itself was far away at the time. Dragonfly, bound for Titan, is scheduled to launch in July 2028 and arrive in 2034.
Putting 1.4 billion km in perspective
- A car driving nonstop at 100 km/h would need about 1,600 years to cover the average distance.
- An airliner at 900 km/h would take around 180 years.
- Saturn is about ten times farther from Earth than the Sun is, and roughly 3,700 times farther than the Moon.
- Sunlight at Saturn is about 90 times weaker than at Earth, which is why the planet, despite its size, shines only about as brightly as the brightest stars.
Even so, Saturn is the most distant planet easily visible to the naked eye; the how to see Saturn guide explains how to find it.
FAQ
How far is Saturn from Earth right now?
It is always somewhere between about 1.2 and 1.66 billion km. Around each opposition it is near the low end for that year, and about six months later, near conjunction, it is roughly 300 million km farther away. Planetarium software or NASA's online ephemeris tools give the exact current value.
How long does light take to travel from Saturn to Earth?
Between about 67 and 92 minutes, depending on the distance. The average is roughly 80 minutes.
Is Saturn closer to Earth than Jupiter?
No. Jupiter orbits at about 5.2 AU and is always much closer, between roughly 590 and 970 million km. Saturn is the next planet out.
When will Saturn be closest to Earth?
The closest oppositions occur when Saturn is near perihelion, which it reaches around 2032. Oppositions in the early 2030s will bring Saturn to about 8.0 AU, some 1.2 billion km.