C/2025 R3 (PanSTARRS)
Oort cloud comet
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C/2025 R3 (PanSTARRS) is a hyperbolic Oort cloud comet and it is unknown if it will survive perihelion passage on 19 April 2026 when it passes 0.499 AU (75 million km) from the Sun.[6] Around perihelion it may reach a naked eye visibility of about apparent magnitude +3.[5][7][8] The comet was discovered by PanSTARRS in images obtained on 8 September 2025.[1] By 20 March 2026 it became visible in 10x50 binoculars.[9]
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Comet C/2025 R3 (PanSTARRS) imaged on 8 April 2026 | |
| Discovery[1] | |
|---|---|
| Discovered by | Pan-STARRS |
| Discovery date | 8 September 2025 |
| Designations | |
| CK25R030[2] | |
| Orbital characteristics[3][4] | |
| Epoch | 20 December 2025 (JD 2461029.5) |
| Observation arc | 213 days |
| Earliest precovery date | 7 September 2025 |
| Number of observations | 659 |
| Aphelion | ≈6300 AU (inbound)[3] ejection (outbound) |
| Perihelion | 0.499 AU (75 million km) |
| Semi-major axis | ≈3100 AU (inbound) |
| Eccentricity | 0.99984 (inbound)[3] 1.00025 (outbound) |
| Orbital period | ≈170000 years (inbound) ejection (outbound) |
| Inclination | 124.73° |
| 38.69° | |
| Argument of periapsis | 162.23° |
| Mean anomaly | -0.0022° |
| Next perihelion | 19 April 2026 |
| TJupiter | -0.498 |
| Earth MOID | 0.487 AU |
| Jupiter MOID | 1.45 AU |
| Physical characteristics | |
| Comet total magnitude (M1) | 11.9±0.7 |
| 5 (2026-04-12)[5] | |
Observational history
Discovery
The comet was spotted in images obtained by the 1.8-m Ritchey-Chretien telescope at Haleakala, Hawaii, as part of the PanSTARRS survey, at an apparent magnitude of about 20. The head of the comet appeared diffuse, about 2.5 arcseconds across, and there was no tail visible.[1] A broad tail 10 arcseconds long was visible in follow-up images by the Canada-France-Hawaii Telescope. On 11 September the comet was 3.60 AU (539 million km) from the Sun.[2]
Follow-up observations
In January the comet was around magnitude 17,[10] but afterwards the comet started to brighten quickly.[6] In mid March it had brighened to about magnitude 9.[5] On 20 March 2026 the comet was detected visually in 10x50 binoculars by Alan Hale.[9] On 21 March the tail of the comet was about one degree long.[11] On April 4 the comet had an apparent magnitude of about 6 and its coma 3 arcminutes across under moonlight and the comet near the horizon.[6]
On 7 April 2026 was 33 degrees from the Sun, its maximum elongation between the two solar conjunctions.[12] On April 8, its ion tail was at least 7 degrees long, but little dust tail was visible. At that time the comet was moving slowly at the western half of the Pegasus Square, but its motion was accelarating as the elongation started to reduce.[10] On April 11 the comet was spotted with naked eye, with an estimated magnitude of 5.1.[5]
It will come to perihelion, at 0.499 astronomical units (74,600,000 km; 46,400,000 mi), on 19 April 2026 when it will be 20 degrees from the Sun.[8] Afterwards it will move between the Sun and Earth and its brightness could be boosted by forward scattering.[7] It will reach solar conjunction on 25 April 2026 around 05:23 UT when it will be 3.5 degrees from the Sun.[13] The comet will pass 0.489 AU (73.2 million km) from Earth on 26 April 2026.[14][8]
Its future (outbound) trajectory shows the comet being ejected from the Solar System.[3]
See also
- C/2025 R2 (SWAN)
- C/2026 A1 (MAPS), a Kreutz sungrazer that was expected to become visible to the naked eye a few weeks before C/2025 R3, before disintegrating on 4 April 2026.