Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to the Golden Gate Bridge (0.94 km diameter)
  • Will pass within 26,874,954 km of Earth in 2106
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation


85774 (1998 UT18) is a small asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified 1998 UT18 as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

1998 UT18 orbits the sun every 607 days (1.66 years), coming as close as 0.94 AU and reaching as far as 1.86 AU from the sun. 1998 UT18 is about 0.9 kilometers in diameter, making it larger than ~97% of asteroids but small compared to large asteroids, comparable in size to the Golden Gate Bridge.

The rotation of 1998 UT18 has been observed. It completes a rotation on its axis every 55.00 hours.

1998 UT18's spectral type None (Tholen) / C (SMASSII) indicates that it is likely to contain water, iron, nickel, cobalt, nitrogen, and ammonia.

Close Approaches

1998 UT18's orbit is 0.04 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.

1998 UT18 has 7 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
Dec. 26, 2106 26,874,954 7.949
Dec. 18, 2111 21,138,355 8.024
Dec. 13, 2116 17,260,820 8.219
Dec. 11, 2121 15,489,812 8.348
Dec. 12, 2126 15,996,281 8.312
Dec. 15, 2131 18,817,021 8.122
Dec. 20, 2136 23,720,680 7.937

Images and Observations

1998 UT18's orbit is determined by observations dating back to April 30, 1989. It was last officially observed on Aug. 7, 2021. The IAU Minor Planet Center records 763 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 1998 UT18:



   or view a random object

Orbital Elements

  • Epoch: 2459396.5 JD
  • Semi-major axis: 1.403 AU
  • Eccentricity: 0.329
  • Inclination: 13.59°
  • Longitude of Ascending Node: 64.65°
  • Argument of Periapsis: 50.13°
  • Mean Anomaly: 184.56°

Physical Characteristics

  • Diameter: 0.93900 km
  • Magnitude: 19.07
  • Albedo: 0.042
  • Spectral type (SMASS): C

Derived Characteristics

  • Orbit Period: 607 days (1.66 years)
  • Avg. Orbit Speed: 25.15 km/s
  • Aphelion Distance: 1.86 AU
  • Perihelion Distance: 0.94 AU
  • Rotation Period: 55.00 hours
  • Approx. Composition: water, iron, nickel, cobalt, nitrogen, and ammonia.

Map Comparison

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Orbit Simulation

Sky Map

The position of 85774 (1998 UT18) 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 1998 UT18 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.