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]

    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.

    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
    170.17 AU (25 million km)[5]± 1.5 billion km[5]1000000
    191.4 AU (210 million km)[6]± 870 million km[6]50000[3]1[3]
    572.5 AU (370 million km)[7]± 18 million km[7]00

    See also

    References

    1. 1 2 "MPEC 2021-U10 : 2021 TP21". IAU Minor Planet Center. 17 October 2021. Retrieved 6 November 2021. (K21T21P)
    2. 1 2 "JPL Small-Body Database Browser: (2021 TP21)". Jet Propulsion Laboratory. Retrieved 6 November 2021.
    3. 1 2 3 4 "(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. 1 2 "JPL Horizons Archive: 2021 TP21 geocentric distance and uncertainty with 17 day arc". JPL Horizons. Archived from the original on 30 October 2021.
    6. 1 2 "JPL Horizons Archive: 2021 TP21 geocentric distance and uncertainty with 19 day arc". JPL Horizons. Archived from the original on 30 October 2021.
    7. 1 2 "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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