P/2010 H2 (Vales)
A distant Jupiter-family comet discovered during a massive outburst.
P/2010 H2 (Vales) is a distant Jupiter-family comet that orbits the Sun once every 7.5 years. Its regular close passes by Jupiter place it in the quasi-Hilda category. As of 2025, it remains the only comet ever found by Slovenian astronomer Jan Vales. The comet was last at perihelion in March 2025 and will return to that point in September 2032. It has not been seen since its discovery in April 2010, when it erupted in a massive outburst that brightened it from magnitude 20 to magnitude 12. Normally, the comet is expected to reach only about magnitude 20 when near perihelion. Its next opposition will occur on 27 June 2026. P/2010 H2 is part of the Unistellar citizen science tracking project. Jan Vales discovered the comet on 16 April 2010 during this outburst. No earlier images of it have been found from before 15 April 2010. Later analysis of Catalina Sky Survey data suggested the outburst had been underway for about 15 hours at the time of discovery, boosting the comet’s brightness by a factor of a thousand. Observations the day after discovery showed its coma had expanded from 24–26 arcseconds across to 34–38 arcseconds. Although the comet’s orbit is relatively short, it was not recovered during its next predicted return in 2017. On 17 March 2023, Toni Scarmato reported spotting an object near the expected position of P/2010 H2, hinting at a possible recovery. However, further analysis in 2024 showed that object did not match the comet’s position, and it is now considered a different body. Further search attempts in 2015 and 2025 from the 4.3-meter Lowell Discovery Telescope failed to recover the comet, indicating a possible absolute nuclear magnitude fainter than 20.6, and a nucleus smaller than 0.5 km in diameter assuming a geometric albedo of 0.04. However it is still likely that it may have become inactive after the 2010 outburst instead of simply disintegrating.
Quick Facts
- Discovery Ref
- CBET_2249
- Discoverer
- Jan Vales
- Discovery Site
- Črni Vrh Observatory
- Discovery Date
- 16 April 2010
- Orbit Ref
- jpldata
- Epoch
- 8 May 2010 (JD 2455324.5)
- Observation Arc
- 141 days / (Not observed in 2010 · 9 · 4)
- Earliest Precovery Date
- 15 April 2010Balanutsa_2010
- Obs
- 1,631
- Perihelion
- 3.108 AU
- Aphelion
- 4.593 AU / (2028-Dec-14)aphelion
- Semimajor
- 3.851 AU
Facts from the source article.
Lore & Background
The comet underwent a massive outburst when it was discovered by Jan Vales on 16 April 2010. No prediscovery observations earlier than 15 April 2010 were found. Later analysis of data from the Catalina Sky Survey indicated that the outburst may have been ongoing for 15 hours at the time, resulting in its brightness increasing by a thousand-fold. Observations conducted on the day after discovery noted that its coma had undergone a significant increase in size, from 24–26 arcseconds to 34–38 arcseconds across. Although calculated to have a relatively short orbital period, it was not recovered during its next apparition in 2017. On 17 March 2023, Toni Scarmato reported the observation of an object close to the predicted position of P/2010 H2, indicating a possible recovery of the comet. Further analysis in 2024 did not match the position of the initial reports, concluding that Scarmato's find is likely a different object. Further search attempts in 2015 and 2025 from the 4.3-meter Lowell Discovery Telescope failed to recover the comet, indicating a possible absolute nuclear magnitude fainter than 20.6, and a nucleus smaller than 0.5 km in diameter assuming a geometric albedo of 0.04. However it is still likely that it may have become inactive after the 2010 outburst instead of simply disintegrating.
Reader's Guide
P/2010 H2 (Vales) is notable as the only comet discovered by Slovenian astronomer Jan Vales as of 2025, and for its dramatic outburst that enabled its discovery. The comet's brightness surged from magnitude 20 to magnitude 12 in April 2010, a thousand-fold increase possibly ongoing for 15 hours. Despite its short orbital period, the comet has not been observed since that outburst, and recovery attempts in 2017, 2023, and 2025 have failed. The 2023 candidate recovery by Toni Scarmato was later determined to likely be a different object. Searches with the 4.3-meter Lowell Discovery Telescope in 2015 and 2025 suggest the nucleus may be smaller than 0.5 km and fainter than absolute magnitude 20.6, leading to the possibility that the comet became inactive after the outburst rather than disintegrating. Its classification as a quasi-Hilda comet due to frequent Jupiter encounters adds to its interest. The comet is part of the Unistellar citizen science tracking project, and its next opposition occurs on 27 June 2026, offering a potential observation window for amateur astronomers.
Did You Know?
- The comet's brightness increased by a thousand-fold during its discovery outburst in April 2010.
- It has not been observed since its discovery outburst in 2010.
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