SpaceWhat is in the solar system?
At the centre is the Sun, a star that holds 99.8% of all the mass. Round it go eight planets. The four nearest, Mercury, Venus, Earth and Mars, are small and rocky. The four beyond, Jupiter, Saturn, Uranus and Neptune, are giants with rings and many moons. By NASA's count the eight planets have 416 moons between them. Pluto, once called the ninth planet, has been classed as a dwarf planet since 2006.
A sense of scale
Earth is 12,756 km across and 149.6 million km from the Sun. Jupiter is 11.2 times as wide as Earth. Neptune, the farthest planet, is 30 times as far from the Sun as we are, and sunlight takes 4.2 hours to reach it. The Moon, our nearest neighbour, is 384,000 km away.
Missions
- ISRO missions: Chandrayaan-1, the Mars Orbiter Mission, Chandrayaan-3 and Aditya-L1.
- NASA missions: Apollo 11, the Voyagers, Hubble, Webb and Perseverance.
The sky from Earth
- Phases of the Moon: why its shape changes through the month.
- Solar eclipses: the kinds, and how to watch safely.
- The seasons: why it is Earth's tilt and not its distance from the Sun.
How this site was made
Space is a subject where numbers get copied from site to site until nobody knows where they began. Here every figure comes from NASA's planetary fact sheet, and every description from a NASA or ISRO page, read on 12 November 2026. The source is named on each page. Where an official page did not say something, this site does not say it either. The About page lists every source.
Common questions
How many planets are there?
Eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto was reclassified as a dwarf planet in 2006.
Which is the largest planet?
Jupiter. It is 142,984 km across, 11.2 times the width of Earth.
Which is the hottest planet?
Venus. NASA's fact sheet gives its mean temperature as 464 °C, hotter than Mercury although Mercury is nearer the Sun.
Where do the facts on this site come from?
From official pages of NASA and ISRO read on 12 November 2026. Each page names its source.
For the shapes and sizes of spheres and their volumes, see our neighbour site Shapes.