Mercury
The smallest planet and the closest to the Sun. With almost no air to hold heat, its nights are colder than Antarctica and its days hot enough to melt lead.
- Diameter
- 4,879 km
- Year
- 88 Earth days
- Moons
- None
Voyager 1 · launched 5 Sep 1977Voyager 2 · launched 20 Aug 1977New Horizons · launched 19 Jan 2006Pioneer 10 · launched 3 Mar 1972Pioneer 11 · launched 6 Apr 1973
Orrery
The Solar System, right now
Placing the planets
Why two scales
Mostly, it is empty
Every picture of the Solar System you have seen squeezes the distances so that the planets fit on a page. The readable scale does the same, so you can see where everything is.
Switch to true scale and the planets shrink to specks you cannot see: if the Sun were a grapefruit in the dome, the Earth would be a grain of salt eleven metres away and Neptune a speck of dust more than three hundred metres down the hill. The labels mark where each world really is.
The eight planets
Venus
Earth’s near twin in size, smothered in clouds of sulphuric acid over an atmosphere ninety times thicker than ours. The hottest planet, even though Mercury is closer to the Sun.
- Diameter
- 12,104 km
- Year
- 225 Earth days
- Moons
- None
Earth
You are here. The only world we know of with oceans of liquid water on its surface, and with anyone looking back.
- Diameter
- 12,742 km
- Year
- 365.25 days
- Moons
- 1
Mars
A cold desert with the tallest volcano and the longest canyon in the solar system. Rivers once ran here; today the water is locked in ice at the poles and underground.
- Diameter
- 6,779 km
- Year
- 687 Earth days
- Moons
- 2
Jupiter
More than twice the mass of all the other planets put together. Its Great Red Spot is a storm wider than Earth that has been raging for at least 190 years.
- Diameter
- 139,820 km
- Year
- 11.9 Earth years
- Moons
- 97 known
Saturn
Light enough to float in a large enough bathtub. Its rings are mostly water ice, 270,000 km across and in places only ten metres thick.
- Diameter
- 116,460 km
- Year
- 29.4 Earth years
- Moons
- 274 known
Uranus
Tipped over on its side, so each pole spends 42 years in sunlight and then 42 in darkness. The first planet discovered with a telescope, by William Herschel in Bath in 1781.
- Diameter
- 50,724 km
- Year
- 84 Earth years
- Moons
- 29 known
Neptune
Found in 1846 by mathematics before anyone saw it, from the way it tugged on Uranus. Its winds are the fastest in the solar system, over 2,000 km an hour.
- Diameter
- 49,244 km
- Year
- 165 Earth years
- Moons
- 16 known
Mission paths
Five ships leaving home
Turn on mission paths in the orrery to watch them fly. Their routes are drawn through the real positions of the planets on the days they flew past, and their distances update as time runs.
- Voyager 1Launched 1977In interstellar space since 2012, still sending data.
- Voyager 2Launched 1977The only spacecraft to visit Uranus and Neptune.
- New HorizonsLaunched 2006Flew past Pluto in 2015 and Arrokoth in 2019.
- Pioneer 10Launched 1972Silent since 2003, coasting toward Aldebaran.
- Pioneer 11Launched 1973Silent since 1995, heading toward the constellation of Aquila.
