2003 EH1, the Quadrantid parent
A dark rock that may be all that is left of a comet seen in 1490, and the parent of the Quadrantids.
Key facts
- Designation
- (196256) 2003 EH1
- Type
- Extinct comet, catalogued as an asteroid
- Orbital period
- about 5.5 years
- Closest to the Sun
- about 1.19 AU (about 178 million km)
- Farthest from the Sun
- about 5.1 AU
- Tilt of orbit
- about 70°
- Nucleus
- about 3 to 4 km across
- Discovered
- by the LONEOS asteroid survey near Flagstaff, Arizona, on 6 March 2003
- Returns
- about every five and a half years
Orbit
2003 EH1 orbits the Sun every five and a half years on a path tilted steeply to the planets. Its orbit is typical of a Jupiter-family comet, but it shows no tail or coma, so it is listed as an asteroid. Dust along this orbit meets Earth in early January at about 41 km/s.
Size and nature
It is about 3 to 4 km across. Its lack of activity, together with the very narrow, young stream of meteors that follows its orbit, suggests that it is an extinct or dormant comet, whose surface ice has gone or is buried.
History
The Quadrantids were first noted in 1825 and named after Quadrans Muralis, a constellation no longer in use, near the handle of the Plough. For almost two centuries their parent was unknown. When 2003 EH1 was found, Peter Jenniskens showed that its orbit matched the shower. Chinese, Korean and Japanese records describe a bright comet in late 1490 and early 1491, and its calculated orbit is similar, so 2003 EH1 may be what remains of it.
Meteor showers
The Quadrantids peak around 3 to 4 January. At their best they reach over 100 meteors an hour, as many as the Perseids or Geminids, but the peak lasts only a few hours, so in many years it falls in daylight or under cloud. The narrow peak shows the dust was shed only about 500 years ago, which fits a break-up around 1490. Over thousands of years, Jupiter's gravity will move the stream away from Earth.
Its meteor showers
- The Quadrantids peak around 3–4 January; about 80 (variable; roughly 60 to 200) an hour at best; 41 km/s
Key dates
| Date | What happened |
|---|---|
| 6 March 2003 | The LONEOS survey discovered 2003 EH1, later shown to be the parent of the Quadrantids. |
Did you know?
The Quadrantids are the only major shower named after a constellation that no longer exists.
Their peak is so short that a few hours' difference in timing decides a good year from a poor one.
Some astronomers think 2003 EH1 and Comet Machholz may share an ancient ancestor.