On April 13, 2029, a rock roughly the size of several football fields will sweep past our planet closer than most people thought possible for an object of its size. Its name is 99942 Apophis, and it is already one of the most talked-about space events of the decade.
Apophis is a near-Earth asteroid about 340 meters (1,100 feet) wide. It was discovered in 2004 and named after the Egyptian god of chaos, a name that has fueled plenty of dramatic headlines ever since. It belongs to the Aten group of asteroids, which have orbits that mostly stay inside Earth's orbit around the Sun.
At its closest, Apophis will pass about 32,000 kilometers (about 20,000 miles) above Earth's surface. That is roughly one tenth of the distance to the Moon, and closer than the ring of geostationary satellites, which orbit at about 35,786 km. The closest approach is expected around 21:46 UTC.
No. In 2004 early calculations gave a small chance of an impact in 2029, which caused real concern. Further observations and radar measurements removed that risk. NASA's Center for Near Earth Object Studies has ruled out an impact in 2029 and for at least the next 100 years.
Bottom line: the 2029 flyby is a spectacle and a scientific opportunity, not a threat.
Asteroids of this size pass this close to Earth only about once every 5,000 to 10,000 years on average. This is why scientists call it a once-in-a-lifetime opportunity: we can study a large asteroid up close, and it happens to be coming to us.
Apophis is a rocky near-Earth asteroid that circles the Sun in just under a year. Its orbit crosses Earth's path, which is why it comes close from time to time. Observations suggest it does not spin neatly around a single axis: it rotates once in roughly 30 hours and appears to tumble, a motion scientists call non-principal axis rotation. Studying exactly how Earth's gravity changes that tumbling is one of the goals of the 2029 observations.
Earth's gravity will pull on Apophis during the encounter and bend its path. After the flyby, its orbit is expected to become slightly larger, which will change its classification from an Aten-type asteroid to an Apollo-type asteroid. The tidal pull may also shake the surface, move loose material and perhaps change the spin. Scientists compare "before" and "after" images and measurements to learn how strong the asteroid really is inside, something we cannot measure from far away.
Yes, if you are in the right region. Apophis is expected to reach about magnitude 3 to 4 in brightness, visible to the naked eye as a moving point of light crossing the sky. Europe, Africa and parts of western Asia get the best view. Read our guide: how to watch the Apophis flyby.
Because the date has become an internet legend, many posts claim that something else is arriving in 2029. There is no scientific evidence for that. See our honest look at it: Will aliens arrive in 2029?
Facts in this article are drawn from public scientific sources. For primary information, see: