Aten
Key facts
- What it is
- Near-Earth asteroid (namesake of the Aten group)
- Size
- About 1 km across
- Discovered
- 1976, by Eleanor Helin
- Spacecraft
- Not yet visited
- Orbit group
- Aten
- Average distance from the Sun
- 0.97 au (about 140 million km)
- Time to go round the Sun
- 347 days
- Closest and farthest from the Sun
- 0.79 to 1.14 au
- Tilt of its orbit
- 18.9°
- Closest its orbit comes to Earth's
- 17,000,000 km (44 times the Moon's distance)
- Spins once every
- 42.2 hours
An au (astronomical unit) is Earth's average distance from the Sun, about 150 million km. Orbit figures are from open tracking data, figures last updated 1 Nov 2026.
Aten was the first asteroid found that spends most of its time closer to the Sun than Earth does. Eleanor Helin discovered it on 7 January 1976 at the Palomar Observatory in California, and it gave its name to the Aten group.
An Aten asteroid has an average distance from the Sun less than Earth's, so its year is shorter than ours, but at its farthest point it swings out beyond Earth's orbit. That means it crosses our orbit from the inside. Aten asteroids are harder to find than other near-Earth asteroids, because they spend much of their time in the part of the sky near the Sun, where telescopes cannot look at night.
Aten itself is about a kilometre across and goes around the Sun in about 347 days, only a little shorter than Earth's year.
A further group, the Atiras, stay entirely inside Earth's orbit and never cross it. They are harder still to spot, and only a few dozen are known. Specially planned searches, made at twilight or from space, are needed to find bodies like these.
Eleanor Helin was a pioneer of asteroid searching. Working with photographic plates at Palomar from the 1970s, she discovered or co-discovered many near-Earth asteroids and comets and started some of the first organised searches for them. Those early surveys laid the groundwork for today's automated sky surveys, which now find thousands of near-Earth asteroids each year.
Aten is named after the Egyptian god of the Sun's disc, a fitting name for an asteroid that stays so close to the Sun.
Coming close to Earth
Its next passes within about 30 million km of Earth, worked out from its orbit. Each one is a safe miss.
| Date | Distance | In Moon distances |
|---|---|---|
| 31 Dec 2032 | 29,000,000 km | 74 |
| 20 Jan 2034 | 20,000,000 km | 52 |
| 14 Jan 2053 | 18,000,000 km | 46 |
| 2 Jan 2072 | 28,000,000 km | 72 |
| 21 Jan 2073 | 21,000,000 km | 54 |
| 13 Jan 2092 | 19,000,000 km | 49 |