The Chi Cygnids meteor shower
Key facts
- Peak
- around 14–15 September, in active years
- Active
- mid-September, mainly in rare active years
- Rate at peak (ZHR)
- usually near zero; weak enhanced activity in 2015
- Speed
- about 19 km/s
- Radiant
- Cygnus (near the star Chi Cygni, along the Swan's neck)
- Parent body
- An undiscovered Jupiter-family comet
Dates shift slightly from year to year. This year's peak is in the events calendar.
The Chi Cygnids are one of the newest named showers. They were noticed in September 2015 and are an example of how modern camera networks can discover a stream almost as it happens.
Discovery. On the night of 14–15 September 2015, two Dutch members of a video network in the Netherlands and Belgium noticed that five meteors recorded over a few hours had almost identical orbits. Cameras in California recorded four more, and a Canadian meteor radar confirmed a small concentration of radiants at the same position the next day. The shower was quickly named the Chi Cygnids and given its own number on the international list.
The parent. The orbits revealed a stream from a Jupiter-family comet: a short-period comet whose orbit has been shaped by Jupiter, typically taking five to ten years to go round the Sun. No such comet is known on this orbit, so the parent is still waiting to be found. Its orbit is only slightly tilted to Earth's, which is why the meteors arrive so slowly.
What to expect. In 2015 the activity was weak and would have been easy to miss by eye; it was the cameras' ability to measure orbits that revealed it. In most other years activity has been very low. If Earth meets a denser part of the stream again, observers would see slow, long meteors from Cygnus.
Viewing from the UK. Cygnus is high overhead in the evening in September from the UK, so the radiant is well placed in the hours after dark.
Viewing worldwide. This is a northern hemisphere shower; from southern latitudes Cygnus is low in the north.
The Chi Cygnids show the value of continuous camera monitoring: without it, short-lived showers from undiscovered comets would pass unrecorded.
Viewing tips
- Watch in the evening, when Cygnus is high overhead from the UK.
- Find the long neck of the Swan; Chi Cygni lies along it, towards Albireo.
- Look for slow, long meteors coming from the Swan.
- Run a camera through mid-September to record any return.
- Record exact times, because short-lived activity is easily missed.