The Alpha Centaurids meteor shower
Key facts
- Peak
- around 8 February
- Active
- late January to about 20 February
- Rate at peak (ZHR)
- about 6 (brief bursts of 20–30 in 1974 and 1980)
- Speed
- 58 km/s
- Radiant
- Centaurus (near Hadar, Beta Centauri)
- Parent body
- Unknown
Dates shift slightly from year to year. This year's peak is in the events calendar.
The Alpha Centaurids are a southern hemisphere shower that radiates from one of the richest parts of the sky, close to the bright stars that point the way to the Southern Cross. They are modest in number but known for bright meteors, including fireballs that leave glowing trains behind them.
History. A probable early sighting came from Sydney in February 1889, and the German astronomer Cuno Hoffmeister probably recorded the shower from what is now Namibia in 1938. It was only properly established in the 1970s, through careful counts by amateur observers in Western Australia. In 1974 and again in 1980, the shower produced short bursts lasting a few hours, with rates equivalent to 20 to 30 meteors an hour. Since then it has mostly been quiet, and reports are sparse, so the stream is still poorly understood.
The radiant. The meteors appear to come from Centaurus, near Hadar (Beta Centauri) and not far from Alpha Centauri, the nearest star system to the Sun. These two stars are the Pointers that lead the eye to the Southern Cross. Despite the name, the radiant is not exactly on Alpha Centauri; showers are named after the brightest star close to the radiant at the time the name was given.
The parent. No parent comet has been identified. The high speed of the meteors, about 58 kilometres per second, suggests a comet on a steeply tilted or retrograde orbit, but that is a clue, not an answer.
What to expect. In a normal year, about five or six meteors an hour under a dark sky, swift and often bright. Because outbursts have happened before, it is worth watching in case of another.
Viewing. The radiant is so far south that it never rises from the UK, Europe or most of the United States; you need to be south of about latitude 30 degrees north to see it at all, and much further south for it to climb high. From Australia, New Zealand, southern Africa and South America it is nearly circumpolar and visible most of the night, highest before dawn.
Viewing tips
- Watch from the southern hemisphere, where the radiant is high in the hours before dawn.
- Find the two Pointers, Alpha and Beta Centauri, beside the Southern Cross.
- Keep watching after a bright meteor, as Alpha Centaurids often leave glowing trains.
- Report your counts, because recent data on this shower are scarce.
- From the UK, look instead for the end of the January showers; this one never rises.