Earth
What is Earth?
Planets· Diameter 12,742 km. The only known living world. Oceans cover 71% of its surface, and its unusually large moon steadies the axial tilt that gives us stable seasons.
The orbit of Earth at this moment: https://nowsky.org/solar/orbit?fw=earth&sp=3 — replayed live, no login.
Orbit and size
| Diameter | 12,742 km |
|---|---|
| Distance | 1 AU (150M km) |
| Year | 365.25 d |
| Moons | 1 — the Moon |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Moons of Earth
Related events
- Comet Hyakutake sweeps past Earth
- Voyager 1 passes one light-day from Earth(planned)
- Europa Clipper Earth flyby(planned)
Frequently asked
- How big is Earth?
- 12,742 km.
- How far is Earth from Earth?
- 1 AU (150M km).
- What are the main moons of Earth?
- Moon.
Earth as seen from other worlds
From the Moon, Earth looks four times the width of a full Moon and its phases run opposite to the Moon's — on a night of a thin crescent Moon here, Earth hangs nearly full there. Because of tidal locking, from any one spot on the near side Earth stays fixed in almost the same place in the sky and never rises or sets. Apollo 8's "Earthrise" was possible only from a command module in orbit.
In the evening sky of Mars, Earth shines like Venus does for us, and a good telescope splits it into a double with the Moon alongside. Curiosity photographed Earth above the Martian horizon in 2014, and in 1990 Voyager 1 captured it as a single pixel from six billion kilometres. Following Mars in the orbit view with Earth as the gaze target reproduces the arrangement.
The planet in depth
Earth is the only world confirmed to keep liquid water stable at its surface. The right distance from the Sun, a magnetic field deflecting the solar wind, plate tectonics cycling carbon, a large Moon steadying the axial tilt — stack those and you get nearly four billion years of unbroken life.
Earth's day is slowly lengthening — about 2 milliseconds per century, paid as tidal friction to the Moon. A dinosaur's day ran about 23.5 hours. The same physics pushes the Moon 3.8 cm farther away each year.
Every sky in this simulator is ultimately "the universe as seen from Earth". Change the observing location in Sky view and watch one latitude reshape the whole night — from Polaris's height to the Milky Way's tilt.
How Earth got its water is an open case — it formed in a zone too warm to keep it, so asteroids and comets likely made the delivery, though the courier's identity is still argued. The result is not in doubt: 71% of the surface is ocean, liquid for nearly four billion years running, and that continuity is what evolution required. Try using Earth as your anchor point on the size ladder.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.