Asteroid Apophis and Its 2029 Close Flyby

What Apophis is

Apophis, officially 99942 Apophis, was first designated 2004 MN4. Roy Tucker, David Tholen and Fabrizio Bernardi found it on June 19, 2004, at Kitt Peak National Observatory in Arizona, and it was recovered on December 20, 2004, at Siding Spring Observatory in Australia.

Published sizes differ by source and method, so treat 340 to 375 m as the range. An astronomical unit (AU) is the average Earth-Sun distance, about 149.6 million km (93 million miles). The Aten group is one of four near-Earth orbit classes, described in the article on near-Earth asteroids. For a broader view of what S-type means, see the guide to what asteroids are.

Why it was once feared, and why that ended

An orbit built from limited observations has a wide margin of error, and in 2004 that margin included the chance of an Earth encounter. ESA says initial observations raised a small chance of impact in 2029, 2036 or 2068, with the 2029 figure reaching as high as 2.7 percent. As more observations arrived, the 2029 and 2036 risks were ruled out, according to JPL. The 2068 possibility lasted longer.

• June 19, 2004: Apophis is discovered at Kitt Peak.
• December 20, 2004: it is recovered at Siding Spring Observatory in Australia.
• Around March 5, 2021: radar from the Goldstone 70-m antenna in California and the Green Bank Telescope in West Virginia measure the asteroid's distance to about 150 m (490 feet).
• March 25, 2021: JPL reports that the orbit uncertainty for 2029 has shrunk from hundreds of kilometers to a handful, and that a 2068 impact is no longer possible. Apophis is removed from NASA's Sentry risk table.
• March 26, 2021: ESA removes Apophis from its Risk List.

JPL's analysis says there is no impact risk for at least the next 100 years. Apophis is still carried as a potentially hazardous asteroid in JPL's database, a label that rests on its size and orbit and not on any forecast of impact.

The April 13, 2029 flyby

At closest approach Apophis will be about 32,000 km (20,000 miles) from Earth's surface. NASA notes that an asteroid this large passes this close only about every few thousand years on average. The distance sits inside the altitude of geosynchronous satellites, about 36,000 km (22,000 miles), and NASA states that there is no danger to Earth.

ESA says that for a short time Apophis will be visible to the naked eye from parts of Europe, Africa and Asia, and JPL describes it as visible from the Eastern Hemisphere without a telescope or binoculars. Anyone planning to look should check local timing and conditions from agency sources first. Never point binoculars or a telescope at the Sun without a proper solar filter made for that purpose.

After the flyby, Earth's gravity will change the asteroid's path. NASA says its orbit is expected to grow to about 1.2 years, and that it will move from the Aten group to the Apollo group. A guide to what those orbit terms mean is in the article on how to read an orbit.

What scientists want to learn

ESA says Earth's gravity will create tidal forces that may stretch and squeeze Apophis, possibly causing quakes and landslides and changing its rotation. The flyby is a chance to watch a small body react to a planet's pull. NASA also says Earth-based telescopes will observe Apophis during the encounter.

OSIRIS-APEX is the OSIRIS-REx spacecraft that delivered the Bennu sample capsule, renamed for its new target. Its first assignment is told in the story of OSIRIS-REx and Bennu. NASA says its thrusters may stir up surface rocks and dust so scientists can see just below.

Ramses is ESA's Rapid Apophis Mission for Space Safety. ESA signed a contract worth 81.2 million euros with OHB Italia on February 10, 2026, to build and test the spacecraft, and lists a spring 2028 launch window. It will carry two CubeSats, small satellites released after arrival, and JAXA is contributing solar arrays and a thermal infrared imager. Its purpose, ESA says, is to study Apophis and gain insight into asteroid physical properties and behavior, which supports planetary defense.

A checklist for reading Apophis news

• Check the date. Stories from 2004 to 2020 describe an older, uncertain orbit.
• Look for the agency wording: NASA says no impact risk for at least 100 years.
• Note that the distance is measured from Earth's surface, about 32,000 km.
• Remember that "potentially hazardous" is a size-and-orbit label, not a forecast.
• Expect size figures between about 340 and 375 m.

Common mistakes and myths

Myth: Apophis will hit Earth in 2029. NASA and ESA both say it will not. ESA states that Apophis poses no risk to Earth during its 2029 flyby. How agencies watch for real hazards, and test a response, is covered in the article on planetary defense and the DART test.

Myth: the 2036 and 2068 dates are still threats. JPL says additional observations ruled out the 2036 risk and the March 2021 radar work ruled out 2068. Apophis was removed from Sentry and from ESA's Risk List.

Myth: Earth's gravity will pull Apophis in during the flyby. The flyby changes its orbit, which grows from about 0.9 to about 1.2 years, according to NASA. JPL's calculations show no impact risk for at least the next 100 years, a span that includes the 2029 flyby.

Myth: it can only be seen through a telescope. ESA and JPL both say it will be visible to the naked eye from parts of the Eastern Hemisphere for a short time.

Frequently asked questions

When is the Apophis flyby?

April 13, 2029, according to NASA and ESA. The closest distance is about 32,000 km (20,000 miles) from Earth's surface.

Will Apophis hit Earth?

NASA says there is no risk of Apophis impacting Earth for at least 100 years. That conclusion rests on radar observations made in March 2021.

How big is Apophis?

NASA and JPL give a mean diameter of about 340 m (1,115 feet), while ESA gives roughly 375 m. The range reflects differences between sources.

Which spacecraft will study it?

NASA's OSIRIS-APEX is planned to arrive in June 2029, and ESA's Ramses is planned to launch in spring 2028 and rendezvous before the April 2029 flyby.