 Comet Väisälä 1 imaged from the Vega Observatory on March 18, 2004. | |
| Discovery[1] | |
|---|---|
| Discovered by | Yrjö Väisälä |
| Discovery site | University of Turku, Finland |
| Discovery date | February 8, 1939 |
| Designations | |
| P/1939 CB P/1949 Y1 | |
| |
| Orbital characteristics[4] | |
| Epoch | May 5, 2025 (JD 2460800.5) |
| Observation arc | 86.16 years |
| Earliestprecovery date | January 18, 1939 |
| Number of observations | 1,243 |
| Aphelion | 8.079 AU |
| Perihelion | 1.824 AU |
| Semi-major axis | 4.951 AU |
| Eccentricity | 0.63169 |
| Orbital period | 11.018 years |
| Inclination | 11.639° |
| 128.90° | |
| Argument of periapsis | 52.029° |
| Mean anomaly | 342.92° |
| Last perihelion | November 15, 2014[2] |
| Next perihelion | November 11-12, 2025[3] |
| TJupiter | 2.535 |
| EarthMOID | 0.823 AU |
| JupiterMOID | 0.077 AU |
| Physical characteristics[5] | |
Mean diameter | 4.2 km (2.6 mi) |
| Comet total magnitude (M1) | 11.6 |
| Comet nuclear magnitude (M2) | 14.8 |
40P/Väisälä is aperiodic comet that was discovered on February 8, 1939. Its orbit was determined on April 26, 1939.[2] In 1994, the diameter of itsnucleus was found to be 4.2 km (2.6 mi), similar in size to that ofComet Encke.[5] It was last observed in March 2025 and will come to perihelion on November 11-12, 2025.
Comet Väisälä was discovered accidentally on photographs exposed forminor planets. Originally, it was given theasteroid designation 1939 CB.[1][5] However, additional findings revealed that the object was of cometary nature. Thevisual magnitude of Väisälä at the time of its discovery was 15. The orbital characteristics of the new comet at the time of its discovery were "a period of about 10 years, aperihelion date of April 26, 1939, and a perihelion distance of 1.75 AU (262 million km)."[1]
The orbit of Comet Väisälä resembles that of many centaurs, and is therefore unstable[6] over thousands of years due to gravitational interactions with the gas giant Jupiter. One such close approach, 0.41 AU (61 million km) on December 31, 1961, increased its perihelion distance from 1.74 AU to 1.87 AU and increased its orbital period from 10.46 to 11.28 years. On September 21, 1973, an approach of Jupiter 1 AU away decreased perihelion distance from 1.87 AU to 1.80 AU decreased orbital period from 11.28 to 10.88 years.[1] Väisälä will make one more close approach in the 21st century,[5] but it will have a minimal effect.[1] However, in the year 2127, the comet will make a close approach of only 0.096 AU from Jupiter, and reduce perihelion to 1.4 AU.[5]
| Numbered comets | ||
|---|---|---|
| Previous 39P/Oterma | 40P/Väisälä | Next 41P/Tuttle–Giacobini–Kresák |
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