2020 QG, also known by its internal designation ZTF0DxQ, is an Earth-crossing asteroid, a few meters in diameter. It belongs to the

Apollo group Apollo Education Group, Inc. is an American corporation based in the South Phoenix area of Phoenix, Arizona, with an additional corporate office in Chicago, Illinois. The company owns and operates several higher-learning institutions, including ...

, and passed above the surface of Earth approximately away (less than half an

Earth radius Earth radius (denoted as ''R''🜨 or R_E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid, the radius ranges from a maximum of nearly (equatorial radius, deno ...

) on 16 August 2020 at 04:09 UT. It was first imaged by the Zwicky Transient Facility (ZTF) at the

Palomar Observatory Palomar Observatory is an astronomical research observatory in San Diego County, California, United States, in the Palomar Mountain Range. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

about 6 hours after this closest approach, and was later identified by Kunal Deshmukh, a student at the Indian Institute of Technology Bombay, along with colleagues Kritti Sharma, Chen-Yen Hsu and Bryce T. Bolin analyzing images from the ZTF. At the time, 2020 QG passed closer to Earth than any known asteroid, except for those that became

meteor A meteoroid () is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as micr ...

s. It passed closer than and 2020 JJ. Given an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 29.8, it is estimated to be around in diameter so similar to Earth-impactors ,

2014 AA 2014 AA was a small Apollo near-Earth asteroid roughly 2–4 meters in diameter that struck Earth on 2 January 2014. It was discovered on 1 January 2014 by Richard Kowalski at the Mount Lemmon Survey at an apparent magnitude of 19 using a reflec ...

2018 LA 2018 LA, also known as ZLAF9B2, was a small Apollo asteroid, Apollo near-Earth asteroid in mean diameter that impacted the atmosphere with small fragments reaching the Earth at roughly 16:44 UTC (18:44 local time) on 2 June 2018 near the border o ...

, and 2019 MO.

Orbit and classification

2020 QG orbits the Sun at approximately 1.0–2.9 AU every 964.2 days (2.64 years) after its 2020 orbital perturbation by its close approach with Earth. Before perturbation, it orbited every 990.5 days (with a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of 1.9 AU). Before its perturbation, flying by Earth, the asteroid's orbit had an eccentricity of 0.49 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 5.5 ° (with respect to the ecliptic). The asteroid came to perihelion (closest approach to the Sun) on 1 August, and then on 16 August 2020 the close approach to Earth reduced its orbital period. From the encounter with the larger gravity field, the orbital eccentricity became 0.48 and the inclination stands at 4.7°. In May 2020, before any perturbation, the asteroid had an Earth-MOID ( Minimum orbit intersection distance) of . Hours before the close approach the Earth-MOID was , the close-approach perturbation (change to orbit) bringing it closer.

Detectability

Asteroids that are similar in size to 2020 QG are difficult to detect because they are small and therefore dim. Between 2010–2020, the asteroid was never brighter than about

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

31 making it about 10 thousand times fainter than a typical discovery magnitude of 21. The

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

needs 3 weeks of exposure time to image magnitude 31 objects and has an extremely small field of view, making serendipitous discoveries essentially impossible at those magnitudes. During the 2020 approach, the asteroid appeared dimmer than magnitude 24 until it had a

solar elongation In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet's position, in its orbital path around t ...

of only 60 degrees. The asteroid was imaged when it had a solar elongation of 125 degrees and was around magnitude 19.

Future approaches

2020 QG will make several close approaches with Earth in the future, albeit at larger distances compared to the August 2020 encounter. The next close approach by 2020 QG will be in May 2028, which it will pass by Earth from a nominal distance of .

Notes

References

External links