Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to Mount Everest
  • Will pass within 6,641,274 km of Earth in 2024
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation


415029 (2011 UL21) is a mid-sized asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified 2011 UL21 as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

2011 UL21 orbits the sun every 1,130 days (3.09 years), coming as close as 0.74 AU and reaching as far as 3.51 AU from the sun. Based on its brightness and the way it reflects light, 2011 UL21 is probably between 1.693 to 3.785 kilometers in diameter, making it larger than 99% of asteroids, very roughly comparable in size to Mount Everest.

The rotation of 2011 UL21 has been observed. It completes a rotation on its axis every 2.73 hours.

Close Approaches

2011 UL21's orbit is 0.02 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.

2011 UL21 has 5 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
June 27, 2024 6,641,274 25.882
June 25, 2089 2,666,337 24.957
July 1, 2123 14,848,598 27.043
June 16, 2154 25,937,869 21.942
June 22, 2188 8,046,580 24.064

Images and Observations

2011 UL21's orbit is determined by observations dating back to Oct. 29, 1989. It was last officially observed on Sept. 5, 2021. The IAU Minor Planet Center records 1,508 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 2011 UL21:



   or view a random object

Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 2.122 AU
  • Eccentricity: 0.6534
  • Inclination: 34.88°
  • Longitude of Ascending Node: 275.33°
  • Argument of Periapsis: 284.95°
  • Mean Anomaly: 282.71°

Physical Characteristics

  • Diameter: ~2.185 km
  • Magnitude: 15.98

Derived Characteristics

  • Orbit Period: 1,130 days (3.09 years)
  • Avg. Orbit Speed: 20.43 km/s
  • Aphelion Distance: 3.51 AU
  • Perihelion Distance: 0.74 AU
  • Rotation Period: 2.73 hours

Map Comparison

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Orbit Simulation

Sky Map

The position of 415029 (2011 UL21) 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 2011 UL21 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.