Key Facts

  • Classified as a Aten-class Asteroid
  • Comparable in size to the U.S. Pentagon (1.32 km diameter)
  • Will pass within 5,182,079 km of Earth in 2019
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation

Overview

66391 (1999 KW4) is a small asteroid whose orbit could bring it in close proximity to Earth. NASA JPL has classified 1999 KW4 as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

1999 KW4 orbits the sun every 188 days (0.51 years), coming as close as 0.20 AU and reaching as far as 1.08 AU from the sun. 1999 KW4 is about 1.3 kilometers in diameter, making it larger than most asteroids, comparable in size to the U.S. Pentagon.

The rotation of 1999 KW4 has been observed. It completes a rotation on its axis every 2.76 days.

Close Approaches

1999 KW4's orbit is 0.01 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.

1999 KW4 has 40 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
May 25, 2019 5,182,079 21.513
May 26, 2020 23,910,464 24.631
June 2, 2034 29,416,418 19.876
May 29, 2035 16,789,425 19.679
May 25, 2036 2,323,201 20.798
May 26, 2037 16,830,313 23.351
May 30, 2052 23,696,140 19.655
May 27, 2053 10,145,942 20.008
May 25, 2054 6,835,794 21.760
May 27, 2055 25,699,175 24.982
June 2, 2069 29,610,873 19.883
May 29, 2070 17,119,795 19.667
May 26, 2071 2,620,687 20.740
May 26, 2072 16,029,902 23.233
June 1, 2087 25,949,635 19.716
May 27, 2088 12,947,017 19.844
May 25, 2089 3,568,610 21.300
May 27, 2090 21,777,573 24.256
May 31, 2105 20,201,288 19.614
May 27, 2106 5,896,773 20.363
May 27, 2107 11,822,134 22.557
June 3, 2122 27,498,712 19.773
May 30, 2123 14,665,363 19.767
May 26, 2124 2,109,515 21.071
May 27, 2125 19,737,759 23.890
May 31, 2140 20,128,566 19.611
May 27, 2141 5,627,701 20.387
May 27, 2142 12,317,701 22.648
June 2, 2157 26,062,243 19.703
May 29, 2158 12,793,963 19.865
May 27, 2159 3,914,907 21.381
May 28, 2160 22,562,238 24.411
June 4, 2174 29,874,531 19.889
May 30, 2175 17,209,383 19.666
May 27, 2176 2,386,265 20.762
May 27, 2177 16,468,218 23.346
June 1, 2192 24,132,394 19.639
May 28, 2193 10,491,941 20.008
May 27, 2194 6,450,746 21.763
May 29, 2195 25,408,798 24.955

Images and Observations

1999 KW4's orbit is determined by observations dating back to May 29, 1998. It was last officially observed on July 16, 2019. The IAU Minor Planet Center records 3,880 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 1999 KW4:

References

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Orbital Elements

  • Epoch: 2458600.5 JD
  • Semi-major axis: 0.642195596279 AU
  • Eccentricity: 0.688720225068
  • Inclination: 38.8825649438°
  • Longitude of Ascending Node: 244.909614761°
  • Argument of Periapsis: 192.618431633°
  • Mean Anomaly: 68.0861382732°

Physical Characteristics

  • Diameter: 1.31700 km
  • Magnitude: 16.5
  • Spectral type (SMASS): S:

Derived Characteristics

  • Orbit Period: 188 days (0.51 years)
  • Avg. Orbit Speed: 37.17 km/s
  • Aphelion Distance: 1.08 AU
  • Perihelion Distance: 0.20 AU
  • Rotation Period: 2.76 days

Size Comparison

Orbit Simulation

Sky Map

The position of 66391 (1999 KW4) 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.