Astronomy:2020 VT4

Short description: Near-Earth asteroid

2020 VT₄

Discovery
Discovered by	ATLAS-MLO
Discovery site	Mauna Loa Obs.
Discovery date	14 November 2020
Designations
MPC designation	2020 VT4
Alternative designations	A10sHcN
Minor planet category	NEO · Apollo (pre-flyby) Aten (post-flyby)
Orbital characteristics
Epoch 17 December 2020 (JD 2459200.5) (post-flyby as pre-flyby was very different)
Uncertainty parameter 5
Observation arc	5 days
|{{{apsis}}}|helion}}	1.092 AU
|{{{apsis}}}|helion}}	0.724 AU
Semi-major axis	0.908 AU
Eccentricity	0.20299
Orbital period	0.86 yr (315.92 d)
Mean anomaly	143.860°
Mean motion	1° 8m 22.286s / day
Inclination	10.173°
Longitude of ascending node	231.422°
|{{{apsis}}}|helion}}	14 November 2020 12:17 UT (pre-flyby)
|{{{apsis}}}|helion}}	53.678°
Earth MOID	0.0002 AU
Physical characteristics
Mean diameter	5–11 m (assumed)
Apparent magnitude	20.0 (current) 17.3 (at discovery)
Absolute magnitude (H)	28.66±0.50 28.7

2020 VT₄ is a tiny near-Earth asteroid that passed 370 km (230 mi) above Earth's surface on 13 November 2020 at 17:20 UTC. The asteroid was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey at the Mauna Loa Observatory fifteen hours after its closest approach to Earth. The Earth encounter perturbed the asteroid's trajectory from an Earth-crossing Apollo-type orbit to an Aten-type orbit, subsequently reducing the asteroid's heliocentric orbital period from 1.5 years to 0.86 years.

2020 VT₄ passed closer to Earth than any known asteroid, except for those that became meteors. It passed closer than 2020 QG and 2011 CQ1, which passed about 3,000 km and 5,500 km from Earth's surface, respectively. Given an estimated absolute magnitude of 28.7, 2020 VT₄ is estimated to be around 5 to 10 metres in diameter. Had it impacted Earth, it would mostly have disintegrated during atmospheric entry and might have left a common strewn field.

Discovery

2020 VT₄ was discovered on 14 November 2020, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey at the Mauna Loa Observatory in Hawaii. The asteroid was discovered fifteen hours after its closest approach to Earth, moving about 0.28 degrees per hour across the constellation Fornax at an apparent magnitude of 17.3. At the time of discovery, 2020 VT₄ was about 0.003 astronomical units (450,000 km; 280,000 mi) from Earth and had a solar elongation of 134 degrees.

The discovery was subsequently reported to the Minor Planet Center's Near-Earth Object Confirmation Page (NEOCP) under the internal designation A10sHcN. Further refinements to the asteroid's preliminary trajectory were made with additional follow-up observations by the Galhassin Robotic Telescope, iTelescope Observatory, and the Glenlee Observatory. The asteroid was also identified in earlier observations by the Zwicky Transient Facility one hour before its discovery by ATLAS-MLO. The asteroid was then confirmed by the Minor Planet Center and announced with the provisional designation 2020 VT₄ on 14 November 2020.

Orbit and classification

2020 VT₄ is currently on an Earth-crossing Aten-type orbit with an orbital semi-major axis of 0.908 AU (136 million km; 84.4 million mi) and an orbital period of 0.86 years or 316 days. With a nominal perihelion distance of 0.724 AU and an aphelion distance of 1.092 AU, 2020 VT₄'s orbit extends from Venus to Earth, resulting in occasional close passes with these planets. The nominal minimum orbit intersection distances (MOID) with Venus and Earth are approximately 0.0351 AU (5,250,000 km; 3,260,000 mi) and 0.0002 AU (30,000 km; 19,000 mi), respectively. 2020 VT₄ has an orbital eccentricity of 0.203 and an inclination of 10.2 degrees to the ecliptic.

Before the Earth encounter on 13 November 2020, 2020 VT₄ had an Apollo-type orbit crossing the paths of Earth and Mars. It had a perihelion distance of 0.989 AU and a semi-major axis of 1.31 AU (196 million km; 122 million mi), with an orbital period of 1.5 years or 550 days. The orbit had an orbital eccentricity of 0.246 and an inclination of 12.9 degrees to the ecliptic. The Jet Propulsion Laboratory's Small-Body Database still provides an Apollo-type osculating orbit for 2020 VT₄ based on the epoch 31 May 2020 (JD 2459000.5) before the Earth encounter; excluding all gravitational perturbations, the given orbit implies the asteroid would have passed perihelion 19 hours after it passed Earth.

Orbital Elements

Parameter	Epoch	Period (p)	Aphelion (Q)	Perihelion (q)	Semi-major axis (a)	Eccentricity (e)	Inclination (i)
Units		(days)	AU				(°)
Pre-flyby	2020-May-31	549.2	1.636	0.989	1.313	0.2462	12.909°
Post-flyby	2020-Dec-17	315.9	1.092	0.724	0.908	0.2028	10.161°

2020 flyby

On 13 November 2020, 15 hours prior to its discovery, 2020 VT₄ passed 373 ± 25 km (232 ± 16 mi) over the South Pacific Ocean at 17:20 UTC. At this time of closest approach, 2020 VT₄'s on-sky position was close to the Sun with a minimum solar elongation of 36 degrees, making it unobservable to Earth-based telescopes. 2020 VT₄ passed closer to Earth than any known asteroid, except for those that became meteors. It passed closer than 2020 QG and 2011 CQ1, which passed about 3,000 km and 5,500 km from Earth's surface, respectively.

Animation of 2020 VT4's orbit - 2020 flyby

Around the Sun

Around the Earth

   Sun ·   2020 VT4 ·   Earth

See also

• List of asteroid close approaches to Earth in 2020
• Asteroid impact prediction

External links

• "Pseudo-MPEC" for A10sHcN , Project Pluto, 14 November 2020
• 2020 VT4 at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemeris · Obs prediction · Orbital info · MOID · Proper elements · Obs info · Close · Physical info · NEOCC
• 2020 VT4 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical Properties · Summary
• 2020 VT4 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters