2021 TP21 is an Apophis-sized asteroid that was discovered on 11 October 2021 when it was 0.5 AU (75 million km) from Earth.[1] This potentially hazardous asteroid (PHA) spends most or its orbit closer to 4 AU (600 million km) from the Sun as objects orbit more slowly when near aphelion (furthest distance from the Sun). 2021 TP21 was rated with a Torino scale of 1 from 31 October 2021 to 4 November 2021 for a potential impact on 27 March 2081.[3] As the observation arc became longer the nominal distance from Earth became further on the potential impact date.

2021 TP21
Discovery[1]
Discovered byMount Lemmon Survey
Discovery date11 October 2021
Designations
2021 TP21
Orbital characteristics[2]
Epoch 2021-Jul-01 (JD 2459396.5)
Uncertainty parameter 6
Observation arc57 days
Aphelion4.2274 AU (Q)
Perihelion0.81425 AU (q)
2.5208 AU (a)
Eccentricity0.67699 (e)
4.00 years
318.4° (M)
Inclination25.404° (i)
8.089° (Ω)
116.3° (ω)
Earth MOID0.03 AU (4.5 million km)
Jupiter MOID1.7 AU (250 million km)
Physical characteristics
Dimensions
  • ~300 m (1,000 ft)[3]
  • 240–540 meters
20.2[2][4]
Nominal approach getting further from Earth with longer observation arc
(27 March 2081 virtual impactor)
Observation
arc
(in days)
JPL Horizons
nominal geocentric
distance (AU)
uncertainty
region
(3-sigma)
Impact
probability
(1 in)
Torino
scale
17 0.17 AU (25 million km)[5] ± 1.5 billion km[5] 100000 0
19 1.4 AU (210 million km)[6] ± 870 million km[6] 50000[3] 1[3]
57 2.5 AU (370 million km)[7] ± 18 million km[7] 0 0

See also

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References

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  1. ^ a b "MPEC 2021-U10 : 2021 TP21". IAU Minor Planet Center. 17 October 2021. Retrieved 6 November 2021. (K21T21P)
  2. ^ a b "JPL Small-Body Database Browser: (2021 TP21)". Jet Propulsion Laboratory. Retrieved 6 November 2021.
  3. ^ a b c d "(Archive 31 October 2021): ESA Risk-List". European Space Agency (ESA). Archived from the original on 31 October 2021.
  4. ^ "2021 TP21 Orbit". Minor Planet Center. Retrieved 6 November 2021.
  5. ^ a b "JPL Horizons Archive: 2021 TP21 geocentric distance and uncertainty with 17 day arc". JPL Horizons. Archived from the original on 30 October 2021.
  6. ^ a b "JPL Horizons Archive: 2021 TP21 geocentric distance and uncertainty with 19 day arc". JPL Horizons. Archived from the original on 30 October 2021.
  7. ^ a b "JPL Horizons Archive: 2021 TP21 geocentric distance and uncertainty with 57 day arc". JPL Horizons. Archived from the original on 6 November 2021.
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