Comet 169P/NEAT
The faint parent of the Alpha Capricornids, a summer shower famous for slow, bright fireballs.
Key facts
- Designation
- 169P/NEAT
- Type
- Jupiter-family comet
- Orbital period
- about 4.2 years
- Closest to the Sun
- about 0.6 AU (about 90 million km)
- Farthest from the Sun
- about 4.2 AU
- Tilt of orbit
- about 11°
- Nucleus
- about 5 km across
- Discovered
- on 15 March 2002 by the Near-Earth Asteroid Tracking survey, catalogued at first as asteroid 2002 EX12
- Returns
- about every four years
Orbit
The comet goes round the Sun every four years, from inside Venus's orbit to the inner edge of Jupiter's realm. Its path is close enough to Earth's that dust shed long ago meets us every July and August, at a slow 23 km/s.
Size and nature
The nucleus is about 5 km across but shows only very weak activity, so it was first logged as an asteroid. A smaller comet, P/2003 T12 (SOHO), follows a very similar orbit, and the two may be pieces of a larger body that broke apart a little over 2,000 years ago.
History
The Near-Earth Asteroid Tracking survey found it in March 2002. Its orbit soon showed that it matched the Alpha Capricornids, a shower whose parent had been uncertain for decades. Peter Jenniskens and colleagues made the link in 2010.
Meteor showers
The Alpha Capricornids are active from early July to mid-August, peaking around 30 July, with only about 5 meteors an hour. What they lack in numbers they make up in brightness: they include a large share of slow, yellowish fireballs, and the radiant is well placed from both hemispheres. Because the debris came from a break-up a few thousand years ago, the stream is still young. Models suggest that over the coming centuries Earth will cross its heart, and the shower may become one of the strongest of the year.
Its meteor showers
- The Alpha Capricornids peak around 30 July; about 5 an hour at best; 23 km/s
Key dates
| Date | What happened |
|---|---|
| 15 March 2002 | The NEAT survey found the object now known as Comet 169P/NEAT, parent of the Alpha Capricornids. |
Did you know?
Alpha Capricornid fireballs move slowly enough to watch for a second or more.
Their parent was found only in 2002, though the shower had been watched for over a century.
The shower may become a major one in the 2200s.