Key Facts

  • Categorized as a Aten-class Asteroid
  • Comparable in size to the island of Manhattan
  • Will pass within 27,223,589 km of Earth in 2022
  • Classified as a Near Earth Asteroid (NEA)
  • Not a Potentially Hazardous Object
  • See orbit simulation


137170 (1999 HF1) is a mid-sized asteroid whose orbit could bring it in close proximity to Earth. NASA JPL has classified 1999 HF1 as a "Near Earth Asteroid" due to its orbit's proximity to Earth, but it is not considered potentially hazardous because computer simulations have not indicated any imminent likelihood of future collision.

1999 HF1 orbits the sun every 271 days (0.74 years), coming as close as 0.44 AU and reaching as far as 1.20 AU from the sun. Based on its brightness and the way it reflects light, 1999 HF1 is probably between 3.255 to 7.278 kilometers in diameter, making it larger than 99% of asteroids, very roughly comparable in size to the island of Manhattan.

The rotation of 1999 HF1 has been observed. It completes a rotation on its axis every 2.32 hours.

Close Approaches

1999 HF1's orbit is 0.17 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 HF1 has 8 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
March 16, 2022 27,223,589 19.709
March 8, 2045 27,937,264 17.084
March 13, 2065 26,202,024 18.882
March 12, 2108 26,312,254 18.074
March 17, 2128 28,142,933 20.048
March 12, 2151 26,892,189 17.661
March 17, 2171 27,013,614 19.445
March 9, 2194 29,278,117 16.769

Images and Observations

1999 HF1's orbit is determined by observations dating back to April 20, 1999. It was last officially observed on July 30, 2021. The IAU Minor Planet Center records 3,797 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 HF1:



   or view a random object

Orbital Elements

  • Epoch: 2459396.5 JD
  • Semi-major axis: 0.8192 AU
  • Eccentricity: 0.4624
  • Inclination: 25.66°
  • Longitude of Ascending Node: 155.86°
  • Argument of Periapsis: 253.4°
  • Mean Anomaly: 88.5°

Physical Characteristics

  • Diameter: ~4.202 km
  • Magnitude: 14.56
  • Spectral type (SMASS): X:

Derived Characteristics

  • Orbit Period: 271 days (0.74 years)
  • Avg. Orbit Speed: 32.89 km/s
  • Aphelion Distance: 1.20 AU
  • Perihelion Distance: 0.44 AU
  • Rotation Period: 2.32 hours

Map Comparison

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Orbit Simulation

Sky Map

The position of 137170 (1999 HF1) 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 above comparison is an artistic rendering that uses available data on the diameter of 1999 HF1 to create an approximate landscape rendering with Mount Everest in the background. This approximation is built for full-resolution desktop browsers. Shape, color, and texture of asteroid are imagined.