(792156) 2020 XR

(792156) 2020 XR is a binary Apollo near-Earth object and potentially hazardous asteroid roughly 390 meters (1,000 feet) in diameter. With a 5-day observation arc it was briefly listed as having a 1 in 11,000 chance of impacting Earth on 1 December 2028, which placed it at the top of the Sentry Risk Table with a Palermo scale rating of -0.70.^[4][5]

(792156) 2020 XR

Discovery[1][2]
Discovered by	Pan-STARRS 2
Discovery site	Haleakala Obs.
Discovery date	4 December 2020
Designations
MPC designation	2020 XR
Minor planet category	NEO–Apollo [2][3] PHA [2]
Orbital characteristics[3]
Epoch 2020-May-31 (JD 2459000.5)
Uncertainty parameter 0
Observation arc	7.8 years[4]
Aphelion	4.0272 AU (602,460,000 km) (Q)
Perihelion	0.97013 AU (145,129,000 km) (q)
Semi-major axis	2.4987 AU (373,800,000 km) (a)
Eccentricity	0.61174 (e)
Orbital period (sidereal)	3.95 yr
Mean anomaly	312.19° (M)
Inclination	13.947° (i)
Longitude of ascending node	249.74° (Ω)
Time of perihelion	8 December 2020
Argument of perihelion	163.01° (ω)
Known satellites	1
Earth MOID	0.00085 AU (127,000 km; 0.33 LD)
Jupiter MOID	1.4 AU (210,000,000 km)
Physical characteristics
Mean diameter	~390 meters (1,000 feet)[4]
Absolute magnitude (H)	19.8[2][3]

Discovery

2020 XR was discovered by Pan-STARRS 2 on 4 December 2020,^[2] when it was 0.426 AU (63.7 million km) from Earth and had a solar elongation of 75°. It came to perihelion on 8 December 2020. On 2 January 2021, it passed 0.328 AU (49.1 million km) from Earth.^[3]

On 13 December 2020, precovery observations from 2013, 2016, and mid-2020 extended the observation arc from 8 days to 7.8 years allowing the asteroid to be removed from the Sentry Risk Table.^[2][4]

Satellite

A satellite was discovered on December 2, 2024 by Goldstone Observatory in California using radar observations. Permanent designation was assigned on March 31, 2025. ^[6]

2024

It was the Earth perturbations of the asteroid in 2024 that determined if an impact was possible in December 2028. On 4 December 2024, the asteroid will pass 0.0147 AU (2.20 million km; 5.7 LD) from Earth with an uncertainty region of about ±800 km.^[3] This will increase the asteroid's orbital period by 10 days.

Orbital period 3 months before and after 2024-Dec-04 Earth approach

Parameter	Epoch (date)	Orbital Period
Units		(days)
Pre-flyby	2024-Sep-04	1441
Post-flyby	2025-Mar-04	1451

2028

On 7 November 2028, the asteroid will pass 0.121 AU (18.1 million km) from Earth.^[3] By 1 December 2028 the asteroid will be 0.19 AU (28 million km) from Earth^[7] with an uncertainty region of about ±10,000 km.^[a]

Notes

1. While the observation arc was only a few days, the uncertainty region on 1 December 2028 was approximately a billion km.