Eros
Key facts
- What it is
- Near-Earth asteroid (Amor group)
- Size
- About 34 km long
- Discovered
- 1898, by Gustav Witt
- Spacecraft
- NEAR Shoemaker (in orbit 2000–2001, landed 2001)
- Orbit group
- Amor
- Average distance from the Sun
- 1.46 au (about 220 million km)
- Time to go round the Sun
- 643 days
- Closest and farthest from the Sun
- 1.13 to 1.78 au
- Tilt of its orbit
- 10.8°
- Closest its orbit comes to Earth's
- 22,000,000 km (58 times the Moon's distance)
- Spins once every
- 5.3 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.
Eros was the first near-Earth asteroid ever discovered. Gustav Witt found it from Berlin on 13 August 1898, and Auguste Charlois photographed it independently in France the same night. Its orbit was quickly found to bring it closer to Earth than any planet does.
That closeness made Eros useful long before spacecraft existed. When it passed near Earth in 1900–1901 and again in 1931, astronomers around the world measured its position against the background stars from different places. The slight differences in direction, known as parallax, allowed them to calculate its distance and hence the scale of the whole Solar System more precisely than before.
Eros is a long, curved body, about 34 kilometres from end to end, shaped a little like a peanut or a saddle. In February 2000 NASA's NEAR Shoemaker became the first spacecraft to orbit an asteroid. It circled Eros for a year, mapping craters, boulders and smooth ponds of fine dust that had collected in low places. On 12 February 2001, at the end of the mission, the team gently landed it on the surface, although it had not been designed to land. It kept sending data for about two weeks.
Measurements of the elements on Eros's surface matched those of ordinary chondrites, the most common meteorites. Eros never comes closer than about 22 million kilometres to Earth, and its orbit does not cross ours. It belongs to the Amor group of asteroids, which approach Earth's orbit from outside without crossing it.
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 |
|---|---|---|
| 24 Jan 2056 | 22,000,000 km | 58 |
| 31 Jan 2093 | 27,000,000 km | 71 |
| 25 Jan 2137 | 22,000,000 km | 58 |
| 3 Feb 2174 | 28,000,000 km | 73 |
| 17 Jan 2181 | 30,000,000 km | 77 |