2021 GW4

2021 GW₄ is an Apollo near-Earth object roughly 5 meters (20 feet) in diameter. It was discovered by the Mount Lemmon Survey on 8 April 2021.^[1] On 12 April 2021 13:01 UTC it passed 19821 km from the surface of Earth.^[3] The uncertainty in the close approach distance was ±30 km.^[4]

2021 GW₄

Discovery[1]
Discovered by	MLS
Discovery site	Mount Lemmon Obs.
Discovery date	8 April 2021
Designations
MPC designation	2021 GW4
Minor planet category	NEO–Apollo[2]
Orbital characteristics[2]
Epoch 2020-Dec-17 (JD 2459200.5)
Uncertainty parameter 6
Observation arc	4 days
Aphelion	2.045 AU (305,900,000 km) (Q)
Perihelion	0.97725 AU (146,195,000 km) (q)
Semi-major axis	1.511 AU (226,000,000 km) (a)
Eccentricity	0.3532 (e)
Orbital period (sidereal)	1.862 yr (678 days)
Mean anomaly	286.5° (M)
Inclination	0.73712° (i)
Longitude of ascending node	201.52° (Ω)
Time of perihelion	6 May 2021
Argument of perihelion	26.568° (ω)
Earth MOID	0.00012 AU (18,000 km; 0.047 LD)
Jupiter MOID	2.9 AU (430,000,000 km)
Physical characteristics
Mean diameter	3–8 meters (CNEOS)
Absolute magnitude (H)	29.5[2]

The Earth approach caused the asteroid to migrate inward and reduced the orbital period by roughly 71 days (from 678 days to 607 days).^[5] As a result of the orbit change, it came to its next perihelion (closest approach to the Sun) on 6 May 2021.

Meteor scientist Peter Brown^[6] and astronomers Jonathan McDowell^[7] and Michael Busch^[8] agree that the fireball near South Florida at 13 April 2021 2:16 UTC was unrelated to 2021 GW₄. The unrelated fireball became visible at 100 kilometers (62 mi) above sea level and airburst at 37 kilometers (23 mi) before entering dark flight and landing in the Atlantic ocean.^[6] Thousands of fireballs occur every day.^[9]