2019 UN13 is a small near-Earth asteroid roughly 1–2 meters in diameter. Even though the asteroid was in the night sky for months, it was fainter than the sky survey limit of apparent magnitude 24 until 29 October 2019 when the asteroid was two million km from Earth. It was discovered on October 31, 2019, passing 6,200 km above Earth's surface.

2020 QG and 2011 CQ1 are the only asteroids known where the nominal orbit passed closer to the surface of Earth. Other asteroids that passed very close to Earth include 2004 FU162, 2018 UA, and 2019 AS5.

An impact by 2019 UN13 would be less significant than the 2018 LA impact.

2019 flyby

5 minute markers of trajectory above the earth near closest approach

Orbit changes

The close approach to Earth lifted the asteroid's aphelion point (furthest distance from the Sun) from 1.33 AU (inside the orbit of Mars) to 2.06 AU (near the edge of the inner asteroid belt). The approach changed the orbit from an Aten asteroid with a semi-major axis less than 1 AU to an Apollo asteroid with a semi-major axis greater than that of the Earth (> 1 AU).

Orbital elements for April 2019 and April 2020
20192020
Orbit typeAtenApollo
Perihelion (closest distance to the Sun)0.64 AU0.83 AU
Semi-major axis (average distance from the Sun)0.98 AU1.4 AU
Aphelion (furthest distance from the Sun)1.3 AU2.0 AU
Orbital period358 days637 days

With the new orbit, 2019 UN13 will come to perihelion 0.83 AU from the Sun on 15 December 2019. Without perturbations, the previous orbit would have come to perihelion in January 2020.

Future

There is a small chance the asteroid will pass 0.0001 AU (15,000 km) from Mars on 26 October 2023. There is also a 1 in 3 million chance the asteroid will impact Earth on 1 November 2111.

See also

Closest non-impacting asteroids to Earth, except Earth-grazing fireballs(using JPL SBDB numbers and Earth radius of 6,378 km)
AsteroidDateDistance from surface of EarthUncertainty in approach distanceObservation arcReference
2025 UC112025-10-30 12:11237 km±11 km1 day (41 obs)
2020 VT42020-11-13 17:21368 km±11 km5 days (34 obs)
2020 QG2020-08-16 04:092939 km±11 km2 days (35 obs)
2021 UA12021-10-25 03:073049 km±10 km1 day (22 obs)
2023 BU2023-01-27 00:293589 km±<1 km10 days (231 obs)
2011 CQ12011-02-04 19:395474 km±5 km1 day (35 obs)
2019 UN132019-10-31 14:456235 km±189 km1 day (16 obs)
2008 TS262008-10-09 03:306260 km±970 km1 day (19 obs)
2004 FU1622004-03-31 15:356535 km±13000 km1 day (4 obs)

External links

  • , Minor Planet Electronic Circular, 1 November 2019
  • , CSS, 1 November 2019
  • , EarthSky, 1 November 2019
  • , Deseret News, 1 November 2019
  • , IAWN – International Asteroid Warning Network
  • at NeoDyS-2, Near Earth Objects—Dynamic Site · · · · · · · ·
  • at the JPL Small-Body Database· · · · ·