Apophis, officially designated 99942 Apophis, is a near-Earth asteroid that has captured worldwide attention since its discovery in 2004. Initially estimated to have a 2.7% chance of impacting Earth in 2029, this asteroid has attracted widespread coverage media and public interest. Fortunately, other observations have confirmed that it will not collide with our planet, including during its approaches in 2029 and 2036.
Measuring about 450 meters in diameter, Apophis will pass 30,600 kilometers (19,000 miles) from Earth on April 13, 2029, making it one of the closest encounters with a significant asteroid in recent history. As scientists prepare to study this intriguing celestial body, upcoming flybys present valuable opportunities for research and public engagement.

What is Apophis?

Apophis, formerly known as 99942 Apophis, is a near-Earth asteroid whose orbit puts it 1.3 times the distance between Earth and the Sun. Since its discovery in 2004, it has received widespread media attention, particularly when it was initially estimated to have a 2.7% chance of impacting Earth in 2029. There was also a brief period during which it was thought to pose a risk in 2036. However, further observations have confirmed that Apophis will not collide with Earth in any of these years.

Upcoming close approaches by Apophis

Although Apophis will not collide with Earth, it will come very close on April 13, 2029. On that day, it will pass just 30,600 kilometers (19,000 miles) from Earth, closer than some of our geostationary satellites. This close encounter is expected to generate public interest, and organizations like the Planetary Society are recommending ways to educate the public about the event. On March 30, 2036, Apophis will be much further away, passing Earth at a distance of 8.4 million kilometers (5.2 million miles), more than 20 times the distance of the Moon.

Origin and discovery of Apophis

The name “Apophis” is derived from Egyptian mythology, where Apophis represents a serpent enemy of Ra, the sun god. Every night, Apophis attempted to engulf the world in darkness, only to be defeated by Ra at dawn.
Apophis was discovered on June 19, 2004 by astronomers Roy Tucker, David Tholen and Fabrizio Bernardi at the Kitt Peak National Observatory in Arizona. Tucker previously received a grant from the Shoemaker Near Earth Object Grant Program, which supports amateur astronomers in their efforts to find, track and characterize near-Earth objects.

Size and structure of Apophis

Determining the exact size and shape of Apophis from Earth is difficult due to its small size. However, radar imaging revealed that Apophis measures about 450 meters (1,500 feet) on its longest axis, comparable to five football fields and taller than the Empire State Building.
Its shortest axis measures approximately 170 meters. The asteroid is likely egg-shaped or perhaps two-lobed, resembling Arrokoth, a small celestial body that NASA’s New Horizons spacecraft encountered in 2019.

What will happen if Apophis hits Earth?

Currently, Apophis is not expected to hit Earth anytime soon. It will definitely miss Earth in 2029 and 2036, and observations made in March 2021 ruled out any risk of impact for at least the next 100 years. Initially, the likelihood of an impact in 2029 was higher because initial observations had not yet refined its trajectory. As more data became available, scientists were able to rule out the possibility of an impact.
If Apophis were to collide with Earth, it would cause significant destruction, the effects of which would be felt hundreds of kilometers from the impact site. The energy released would be equivalent to over 1,000 megatons of TNT, similar to multiple nuclear explosions. In comparison, the asteroid that caused the extinction of the dinosaurs was much larger, measuring at least 10 to 15 kilometers across.

Will Apophis hit our satellites?

Apophis will not collide with our geostationary communications satellites. Although it passes closer than some of these satellites, its trajectory is away from the equator, ensuring that it does not enter the region occupied by these vital communications systems.

Will we be able to see Apophis?

Yes, during its close approach in 2029, Apophis will be visible from Europe, Africa and western Asia, appearing as a bright star moving across the sky. By 2036, it will be too far away to see without a telescope.

How do astronomers track asteroids?

Astronomers monitor asteroids like Apophis through a combination of follow-up observations and follow-up efforts. These observations are collected from professional astronomers and trained amateurs and then submitted to the Minor Planet Center. Teams from NASA’s Jet Propulsion Laboratory and the NEODyS program in Italy calculate the orbits of asteroids from this data. The accuracy of these predictions is determined by the quality and quantity of observations.
In some cases, radar is used to obtain precise distance measurements, thereby refining orbital predictions. Additionally, spacecraft missions to near-Earth asteroids provide even more precise orbital data.

Future missions to Apophis

NASA’s OSIRIS-APEX mission will study Apophis for 18 months starting in April 2029, just before its close encounter with Earth. This mission uses the OSIRIS-REx spacecraft, which recently returned samples from the asteroid Bennu.
OSIRIS-APEX will study how Earth’s gravity affects the rotation and surface properties of Apophis. This study could provide valuable information about the asteroid and help scientists learn how to deflect similar objects that could threaten Earth in the future. As close encounters with Apophis approach, continued research and public education will be important to understanding this fascinating asteroid.
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