240P/NEAT

240P/NEAT
Comet 240P/NEAT photographed from the Zwicky Transient Facility on 12 December 2018.
Discovery
Discovered byK. J. Lawrence
Discovery siteNEAT–Palomar
Discovery date7 December 2002
Designations
P/2002 X2, P/2010 P1
NEAT 12
Orbital characteristics
Epoch21 November 2025 (JD 2461000.5)
Observation arc23.64 years
Earliest precovery date5 October 2002
Number of
observations		7,754
Aphelion5.602 AU
Perihelion2.12163 AU (A)
2.12167 AU (B)
Semi-major axis3.861 AU
Eccentricity0.4506
Orbital period7.59 years
Inclination23.54°
74.91°
Argument of
periapsis		352.08°
Last perihelion19 December 2025 (A+B)
Next perihelion5 July 2033 (B+A)
TJupiter2.758 (A+B)
Earth MOID1.145 AU (A)
1.137 AU (B)
Jupiter MOID0.242 AU (A)
0.235 AU (B)
Physical characteristics
Mean radius
2.665 km (1.656 mi)
Fragments:
  • (A) = 0.2–0.3 km (0.12–0.19 mi)
  • (B) = 0.025–0.15 km (0.016–0.093 mi)
Comet total
magnitude (M1)		10.3
12.0
(2025-11-20)

240P/NEAT is a Jupiter-family comet with an orbital period of 7.61 years. It was discovered by Near Earth Asteroid Tracking (NEAT) on 7 December 2002.

The comet came opposition on 22 November 2025, and came to perihelion on 19 December 2025 when it was around magnitude 12-13.

Observational history

The comet at discovery had an apparent magnitude of 18.4, and further observations revealed it had a coma about 8 arcseconds across and a tail 14 arcseconds long. The comet was spotted in prediscovery images dating from 5 October and 6 December by LONEOS and from 5 November by NEAT. Based on these observations it was recognised it is a periodic comet with an orbital period of 8.1 years. The comet was recovered independently by H. Taylor, H. Sato, Leonid Elenin, and T. Yusa on 9, 10, 11, and 11 August 2010 respectively, at an estimated magnitude of around 17. It received its official numerical designation (240P) alongside six other comets on August 2010.

The comet had a close approach to Jupiter on 10 July 2007 at a distance of 0.252 AU (37.7 million km) which reduced the orbital period to 7.6 years and the perihelion distance from 2.5 to 2.1 AU. The comet experienced three events of significant brightening which last for three to six months during its next two perihelia, on March-April 2011, July-August 2017, and on November-December 2018. The events more likely are the result of the warming of previously insulated material due to the reduction of the perihelion distance. The new activity takes place in one or two locations of the nucleus.

240P-B

240P/NEAT with fragmant B on 27 November 2025

On 3 October 2025 fragment 240P-B was imaged by Kitt Peak and reported by V. Carvajal. 240P-B also came to perihelion on 19 December 2025, about 51 minutes after the main body and about 0.00004 AU (6,000 km; 3,700 mi) farther from the Sun.

2025 perihelion passage
Fragment Perihelion time Perihelion distance
240P-A2025-Dec-19 22:522.12163 AU (317,391,000 km; 197,218,000 mi)
240P-B2025-Dec-19 23:432.12167 AU (317,397,000 km; 197,222,000 mi)

The separation (∼108 m) and the rate of change of the separation (∼1 m s−1) of 240P-A from 240P-B point to splitting of the precursor nucleus at least three years before the present observations. The radius of 240P-B is uncertain, with a best estimate ∼300 m and an absolute lower limit 50 m. The mass loss of 240P-B peaked at ∼35 kg s−1 around perihelion, and the total ejected mass was 2.3×108 kg. The likely cause of the splitting is rotational instability triggered by outgassing torques. Both 240P-A and 240P-B are liable to further breakup and destruction by rotational instability on timescales that are shorter than the timescale due to sublimation mass loss.

Notes

  1. ↑ Observation arc from the Minor Planet Center database covering dates from 5 October 2002 until 26 May 2026.
  2. ↑ Estimated size of the original nucleus is approximately 5.33 km (3.31 mi) in diameter based on NEOWISE observations before fragmenting around October 2025.

References

  1. 1 2 3 4 K. J. Lawrence; R. Bambery; E. Helin; S. Pravdo; M. Hicks; et al. (9 December 2002). D. W. Green (ed.). "Comet P/2002 X2 (NEAT)". IAU Circular. 8029 (1). Bibcode:2002IAUC.8029....1L. ISSN 0081-0304.
  2. ↑ "Periodic Comet Names and Designations". Planetary Data System: Small Body Node. NASA. Retrieved 25 October 2026.
  3. ↑ "240P/NEAT Orbit". Minor Planet Center. Retrieved 29 September 2025.
  4. 1 2 3 "Horizons Batch for 240P/NEAT (90001205) on 2025-Dec-19" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 3 October 2025. Retrieved 1 March 2026. (Soln.date: 2026-Feb-27)
  5. 1 2 3 4 "Horizons Batch for 240P-B (90001206) on 2025-Dec-19" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 1 March 2026. Retrieved 1 March 2026. (Soln.date: 2026-Feb-27)
  6. ↑ "Horizons Batch for 240P-B (90001206) on 2033-Jul-05" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 17 April 2026.
  7. ↑ "Horizons Batch for 240P/NEAT (90001205) on 2033-Jul-05" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 17 April 2026.
  8. 1 2 "240P/NEAT – Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 22 August 2025.
  9. 1 2 J. M. Bauer; T. Grav; Y. R. Fernández; et al. (2017). "Debiasing the NEOWISE Cryogenic Mission Comet Populations". The Astronomical Journal. 154 (2): 53–62. Bibcode:2017AJ....154...53B. doi:10.3847/1538-3881/aa72df.
  10. 1 2 3 D. C. Jewitt; J. Luu; Y. Kim (2026). "Investigation of Split Comet 240P/NEAT" (PDF). The Astronomical Journal. 172 (2): 113–123. arXiv:2606.21609. Bibcode:2026AJ....172..113J. doi:10.3847/1538-3881/ae83ac.
  11. ↑ "COBS Observation list: 240P". COBS – Comet OBServation database. Crni Vrh Observatory. Retrieved 21 November 2025.
  12. ↑ S. Yoshida. "240P/NEAT". www.aerith.net. Retrieved 22 August 2025.
  13. ↑ H. Taylor; H. Sato; L. Elenin; T. Yusa; et al. (August 2010). D. W. Green (ed.). "Comet P/2010 P1 (NEAT)". IAU Circular. 9159 (2). Bibcode:2010IAUC.9159....2T. ISSN 0081-0304.
  14. ↑ K. Kadota; R. Bambery; E. Helin; et al. (12 August 2010). "P/2002 X2 (NEAT) = P/2010 P1". Minor Planet Electronic Circulars. 2010-P51. Bibcode:2010MPEC....P...51K. ISSN 1523-6714.
  15. ↑ D. W. Green (August 2010). "Numbering of Periodic Comets". IAU Circular. 9164 (1). Bibcode:2010IAUC.9164....1G. ISSN 0081-0304.
  16. ↑ K. Kinoshita. "240P/NEAT". jcometobs.web.fc2.com. Retrieved 22 August 2025.
  17. ↑ H. Sato (August 2017). D. W. Green (ed.). "Comet 240P/NEAT". Central Bureau Electronic Telegrams. 4427 (1). Bibcode:2017CBET.4427....1S.
  18. ↑ M. S. P. Kelley; D. Bodewits; Q. Ye; T. L. Farnham; E. C. Bellm; et al. (2019). "Comet 240P/NEAT Is Stirring". The Astrophysical Journal Letters. 886 (1): L16. arXiv:1911.02383. Bibcode:2019ApJ...886L..16K. doi:10.3847/2041-8213/ab53e0.
  19. ↑ V. Carvajal; et al. (6 October 2025). "Comet 240P-B/NEAT". Minor Planet Electronic Circulars. 2025-T124. Bibcode:2025MPEC....T..124R. doi:10.48377/MPEC/2025-T124. ISSN 1523-6714.
  20. ↑ "Spying on a Split Comet". Sky & Telescope. 18 August 2026.