Comet Tsuchinshan–ATLAS

C/2023 A3 (Tsuchinshan–ATLAS)
(Great Comet of 2024)
Comet Tsuchinshan-ATLAS photographed from Ohio, USA on 17 October 2024
Discovery
Discovery sitePurple Mountain Obs.
ATLASSAAO (M22)
Discovery date9 January 2023
Designations
C/2023 A3
A10SVYR
Orbital characteristics
Epoch10 February 2024 (JD 2460350.5)
Observation arc3.5 years (1,280 days)
Earliest precovery date9 April 2022
Number of
observations
7240
Aphelion97000 AU(inbound)
Perihelion0.39143 AU
Semi-major axis48000 AU (inbound)
Eccentricity0.999992 (inbound)
1.000039 (outbound)
Orbital periodmillions of years (inbound)
Ejection trajectory (outbound)
Max. orbital speed67.33 km/s
Inclination139.112°
21.559°
Argument of
periapsis
308.491°
Last perihelion27 September 2024
TJupiter–0.583
Earth MOID0.27503 AU
Jupiter MOID1.09559 AU
Physical characteristics
Mean radius
<5.9 ± 0.2 km (3.67 ± 0.12 mi)
Mass(4.3±0.8)×1014 kg
0.04 (assumed)
Comet total
magnitude
(M1)
6.5
Comet nuclear
magnitude (M2)
9.2 ± 0.3
–4.9
(2024 perihelion)

Comet Tsuchinshan–ATLAS, also known as the Great Comet of 2024 and formally designated as C/2023 A3, is a non-periodic comet from the Oort cloud discovered by the Purple Mountain Observatory in China on 9 January 2023 and independently found by ATLAS South Africa on 22 February 2023. The comet passed perihelion at a distance of 0.39 AU (58 million km; 36 million mi) on 27 September 2024, when it became visible to the naked eye. Tsuchinshan–ATLAS peaked at its brightest magnitude on 9 October, shortly after passing the Sun, with an apparent magnitude of −4.9 per reported observations at the Comet Observation Database (COBS), making it the brightest comet observed in the Northern Hemisphere since Comet Hale–Bopp in 1997.