Comet Schwassmann–Wachmann 3
A comet caught falling to pieces, which gave the Tau Herculid shower its first real display in 2022.
Key facts
- Designation
- 73P/Schwassmann–Wachmann
- Type
- Jupiter-family comet (breaking apart)
- Orbital period
- about 5.4 years
- Closest to the Sun
- about 0.97 AU (about 145 million km)
- Farthest from the Sun
- about 5.2 AU, at Jupiter's distance
- Tilt of orbit
- about 11°
- Nucleus
- originally perhaps 1 to 2 km; now dozens of fragments
- Discovered
- by Arnold Schwassmann and Arno Wachmann at Hamburg on 2 May 1930
- Returns
- at perihelion in 2022; next in 2027
Orbit
The comet goes round the Sun every five and a half years, from just inside Earth's orbit out to Jupiter's. Its dust meets Earth slowly, at about 16 km/s, so its meteors are leisurely and faint.
Size and nature
In 1995 the comet suddenly brightened hundreds of times over. It had split into at least four pieces. By its pass in 2006 it had broken into more than 60 fragments, some no bigger than a house, strung out along its orbit. The Hubble Space Telescope watched smaller pieces shedding from the larger ones like sparks. The comet is a living example of how comets end their lives, and of where meteor showers come from.
History
Arnold Schwassmann and Arno Wachmann found the comet on photographic plates at Hamburg in 1930. That same year it passed only about 9 million km from Earth, and a meteor shower from Hercules was expected, but only a few meteors were reported. The comet was then lost until 1979. In May 2006 its fragments swept past Earth at about 12 million km.
Meteor showers
After the 1995 break-up, astronomers calculated that its fresh dust would reach Earth's path in 2022. On the night of 30 to 31 May 2022 observers in North America saw a modest Tau Herculid outburst, with slow, faint meteors. The display was weaker than the most hopeful forecasts but confirmed that the break-up had thrown off dust at fairly low speed.
Missions
The CONTOUR spacecraft was meant to visit this comet in 2006, but was lost in 2002.
Its meteor showers
- The Tau Herculids peak around 30–31 May, mainly in outburst years; about usually very low; about 60 during the outburst of 31 May 2022 an hour at best; about 16 km/s
Space missions
- CONTOUR A mission to compare comets that was lost six weeks after launch.
Key dates
| Date | What happened |
|---|---|
| 2 May 1930 | Arnold Schwassmann and Arno Wachmann discovered their third comet, 73P. |
| 31 May 2022 | The Tau Herculids, from the break-up of Comet Schwassmann–Wachmann 3, gave a small outburst over North America. |
Did you know?
The 3 in its common name tells you it was the third comet Schwassmann and Wachmann found together.
Over 60 fragments were counted in 2006; most are probably gone now.
Its meteors in 2022 entered the air at only about 16 km/s, among the slowest meteors seen.