Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to the Golden Gate Bridge
  • Will pass within 4,911,166 km of Earth in 2022
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation

Overview

138971 (2001 CB21) is a small asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified 2001 CB21 as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

2001 CB21 orbits the sun every 384 days (1.05 years), coming as close as 0.69 AU and reaching as far as 1.38 AU from the sun. Based on its brightness and the way it reflects light, 2001 CB21 is probably between 0.555 to 1.242 kilometers in diameter, making it small in absolute terms, but larger than ~97% of asteroids, very roughly comparable in size to the Golden Gate Bridge.

The rotation of 2001 CB21 has been observed. It completes a rotation on its axis every 3.30 days.

Close Approaches

2001 CB21's orbit is 0.02 AU from Earth's orbit at its closest point. This means that there is an wide berth between this asteroid and Earth at all times.

2001 CB21 has 21 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
March 4, 2022 4,911,166 12.017
Sept. 29, 2026 8,096,858 10.228
March 6, 2043 4,815,314 10.779
Oct. 1, 2047 5,384,739 11.329
Feb. 26, 2063 25,969,410 16.375
March 11, 2064 22,273,371 7.431
Sept. 17, 2067 27,512,734 6.758
Oct. 6, 2068 21,111,841 15.270
March 3, 2084 6,502,633 12.440
Sept. 27, 2088 11,955,361 9.412
March 3, 2105 11,007,459 13.374
Sept. 24, 2109 22,088,005 7.542
Oct. 9, 2110 24,341,263 15.889
March 9, 2127 10,661,230 9.501
Oct. 2, 2131 5,685,863 11.404
March 6, 2148 3,616,428 11.076
Sept. 30, 2152 6,538,794 10.759
March 7, 2169 4,241,838 10.838
Oct. 2, 2173 5,727,702 11.423
March 1, 2189 17,453,677 14.671
Sept. 25, 2193 18,541,992 8.168

Images and Observations

2001 CB21's orbit is determined by observations dating back to Feb. 2, 2001. It was last officially observed on Jan. 24, 2020. The IAU Minor Planet Center records 1,139 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 2001 CB21:

References

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Orbital Elements

  • Epoch: 2459000.5 JD
  • Semi-major axis: 1.034 AU
  • Eccentricity: 0.3335
  • Inclination: 7.9°
  • Longitude of Ascending Node: 353.73°
  • Argument of Periapsis: 271.8°
  • Mean Anomaly: 55.94°

Physical Characteristics

  • Diameter: ~0.717 km
  • Magnitude: 18.4

Derived Characteristics

  • Orbit Period: 384 days (1.05 years)
  • Avg. Orbit Speed: 29.29 km/s
  • Aphelion Distance: 1.38 AU
  • Perihelion Distance: 0.69 AU
  • Rotation Period: 3.30 hours

Map Comparison

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Orbit Simulation

Sky Map

The position of 138971 (2001 CB21) 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.