Apophis
Key facts
- What it is
- Near-Earth asteroid (Aten group)
- Size
- About 340 m across
- Discovered
- 2004, at Kitt Peak, Arizona
- Spacecraft
- OSIRIS-APEX due to arrive in 2029
- Orbit group
- Aten
- Average distance from the Sun
- 0.92 au (about 140 million km)
- Time to go round the Sun
- 324 days
- Closest and farthest from the Sun
- 0.75 to 1.1 au
- Tilt of its orbit
- 3.3°
- Closest its orbit comes to Earth's
- 16,000 km (0 times the Moon's distance)
- Spins once every
- 30.6 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.
Apophis is an asteroid about 340 metres across that will make a spectacular but completely safe pass by Earth on 13 April 2029. It will come within about 32,000 kilometres of the surface, closer than the satellites that hover above the equator in geostationary orbit. For a few hours it will be visible to the unaided eye as a moving point of light from Europe, Africa and western Asia. On average, an asteroid this large passes this close only about once in a thousand years.
Apophis became famous soon after its discovery in June 2004. Early in its tracking, when only a few weeks of observations were available, the calculated chance of a collision in 2029 rose briefly to about 3 per cent. That is normal: when an orbit is poorly known, the range of possible paths is wide, and Earth can fall inside it. Within days, older images of Apophis were found, and the extra measurements showed that it would miss in 2029.
Later passes in 2036 and 2068 were studied for years. In 2021 radar measurements during a distant pass fixed its orbit so precisely that any risk of impact for at least the next hundred years was ruled out.
Scientists are now preparing to make the most of 2029. NASA's OSIRIS-APEX, the spacecraft that sampled Bennu, has been redirected to meet Apophis soon after the pass and watch how Earth's gravity tugs at its shape and spin. Apophis is named after an Egyptian serpent god of chaos.
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 |
|---|---|---|
| 13 Apr 2029 | 38,000 km | 0.1 |
| 24 Aug 2044 | 12,000,000 km | 31 |
| 20 Apr 2051 | 6,200,000 km | 16 |
| 16 Sept 2066 | 10,000,000 km | 27 |
| 27 Jul 2073 | 17,000,000 km | 44 |
| 9 May 2080 | 13,000,000 km | 34 |