2021 SP4

Very small Apollo-class Asteroid

Near-Earth Potentially Hazardous
Space Reference » Apollo-class Asteroids » 2021 SP4

Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to a football field
  • Will pass within 21,452,952 km of Earth in 2022
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation

Overview

2021 SP4 is a very small asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified 2021 SP4 as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

2021 SP4 orbits the sun every 649 days (1.78 years), coming as close as 0.87 AU and reaching as far as 2.06 AU from the sun. Based on its brightness and the way it reflects light, 2021 SP4 is probably between 0.171 to 0.382 kilometers in diameter, making it a small to average asteroid, very roughly comparable in size to a football field.

Close Approaches

2021 SP4's orbit is 0.05 AU from Earth's orbit at its closest point. This means that there is a wide berth between this asteroid and Earth at all times.

2021 SP4 has 12 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
Jan. 30, 2022 21,452,952 9.046
Jan. 30, 2038 21,363,400 9.054
Jan. 29, 2054 21,586,536 9.054
Jan. 26, 2070 22,192,710 9.048
Jan. 19, 2086 23,212,071 8.977
Jan. 11, 2102 24,098,945 8.843
Jan. 2, 2118 24,641,314 8.690
Dec. 21, 2133 24,967,491 8.731
Dec. 11, 2149 25,422,980 9.408
Dec. 4, 2165 26,918,479 10.622
Nov. 30, 2181 29,620,394 11.972
April 2, 2189 26,015,353 14.521

Images and Observations

2021 SP4's orbit is determined by observations dating back to Sept. 28, 2005. It was last officially observed on June 4, 2022. The IAU Minor Planet Center records 166 observations used to determine its orbit.

Accessibility and Exploration

This asteroid is not considered a viable target for human exploration by the NHATS study.

Similar Objects

These objects have orbits that share similar characteristics to the orbit of 2021 SP4:

References

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Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 1.468 AU
  • Eccentricity: 0.405
  • Inclination: 9.91°
  • Longitude of Ascending Node: 161.33°
  • Argument of Periapsis: 324.96°
  • Mean Anomaly: 330.03°

Physical Characteristics

  • Diameter: ~0.221 km
  • Magnitude: 20.96

Derived Characteristics

  • Orbit Period: 649 days (1.78 years)
  • Avg. Orbit Speed: 24.61 km/s
  • Aphelion Distance: 2.06 AU
  • Perihelion Distance: 0.87 AU

Map Comparison

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Orbit Simulation

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Sky Map

The position of 2021 SP4 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 2021 SP4 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.