Apophis

99942 Apophis (2004 MN4)

Near-Earth Potentially Hazardous
Space Reference » Aten-class Asteroids » Apophis

Key Facts

  • Categorized as a Aten-class Asteroid
  • Comparable in size to the U.S. Capitol building (0.34 km diameter)
  • Will pass within 16,852,647 km of Earth in 2021
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation

Overview

Apophis is a very small asteroid whose orbit could bring it in close proximity to Earth. NASA JPL has classified Apophis as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

Apophis orbits the sun every 324 days (0.89 years), coming as close as 0.75 AU and reaching as far as 1.10 AU from the sun. Apophis is about 0.3 kilometers in diameter, making it larger than 90% of asteroids but tiny compared to large asteroids, comparable in size to the U.S. Capitol building.

The rotation of Apophis has been observed. It completes a rotation on its axis every 30.56 hours.

Apophis's spectral type None (Tholen) / Sq (SMASSII) indicates that it is likely to contain and .

Close Approaches

Apophis's orbit is 0.00 AU from Earth's orbit at its closest point. This means that its orbit is very close to Earth's orbit.

Apophis has 10 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
March 6, 2021 16,852,647 4.585
April 13, 2029 38,012 7.423
Aug. 24, 2044 12,016,712 3.955
April 20, 2051 6,201,717 4.695
Sept. 16, 2066 10,406,426 7.763
July 27, 2073 16,793,463 4.566
May 9, 2080 13,005,068 4.198
April 7, 2087 14,333,334 8.659
Sept. 11, 2102 3,505,412 5.662
April 12, 2116 2,911,545 6.444

Images and Observations

Apophis's orbit is determined by observations dating back to March 15, 2004. It was last officially observed on May 12, 2021. The IAU Minor Planet Center records 7,300 observations used to determine its orbit.

Accessibility and Exploration

Apophis can be reached with a journey of 354 days. This trajectory would require a delta-v of 6.049 km/s. To put this into perspective, the delta-v to launch a rocket to Low-Earth Orbit is 9.7 km/s. There are 272,328 potential trajectories and launch windows to this asteroid.

See more at the NHATS Mission Trajectories table for Apophis.

Similar Objects

These objects have orbits that share similar characteristics to the orbit of Apophis:

References

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Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 0.9227 AU
  • Eccentricity: 0.1914
  • Inclination: 3.34°
  • Longitude of Ascending Node: 203.96°
  • Argument of Periapsis: 126.6°
  • Mean Anomaly: 142.86°

Physical Characteristics

  • Diameter: 0.34000 km
  • Magnitude: 19.09
  • Albedo: 0.35
  • Spectral type (SMASS): Sq

Derived Characteristics

  • Orbit Period: 324 days (0.89 years)
  • Avg. Orbit Speed: 30.98 km/s
  • Aphelion Distance: 1.10 AU
  • Perihelion Distance: 0.75 AU
  • Rotation Period: 30.56 hours
  • Approx. Composition: and .

Map Comparison

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Orbit Simulation

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Sky Map

The position of Apophis is indicated by a ◯ pink circle. Note that the object may not be in your current field of view. Use the controls below to adjust position, location, and time.

Size Rendering

The below comparison is an artistic rendering that uses available data on the diameter of Apophis to create an approximate landscape rendering with New York City in the background. This approximation is built for full-resolution desktop browsers. Shape, color, and texture of asteroid are imagined.