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Speed is the signature
Orionids strike the atmosphere at about 66 km per second, among the fastest of any shower. They tend to be faint but sharp, with quick flashes that are easy to miss if you look away for a moment. A good number of them leave short-lived glowing trains.
Their speed is a clue to their origin: the grains come from a comet moving in the opposite direction to the planets, so the collision is nearly head-on.
Under the hunter's club
The radiant is close to the club of Orion, near the bright red star Betelgeuse. Orion climbs the eastern sky after about 10 pm in October, and is highest in the south before dawn. Finding the three belt stars and looking just above and to the left of Betelgeuse points you right.
Meteors close to the radiant have short trails, because they come almost straight at you, and those further away have long ones.
Because Orion is one of the easiest constellations to recognise, this shower makes a friendly introduction for beginners. If you can find the belt and the red shoulder star, you already know where the meteors fan out from, and the rest is simply lying still and looking.
A broad, steady peak
The Orionid maximum is flat, so several nights around the date give similar counts. This helps when clouds block one night. Rates sometimes surprise: in a few years around 2006 to 2009, the ZHR rose to around 50 to 70.
Tips for an autumn night
- Wait for Orion to rise. The best hours are between midnight and dawn.
- Stay warm. Autumn nights can turn cold quickly after the sky clears.
- Mind the Moon. The shower lasts more than a month, so a bad Moon on the peak night still leaves clearer nights in the first days of November.
- Try both sides of the equator. The radiant lies close to the celestial equator, so the shower works from both the north and the south.
A family connection
The spring cousin of this shower is the Eta Aquariids, from the same comet. For the whole calendar, see the meteor showers hub, and for lunar timing the Moon phases hub.
Questions people ask
Are the Orionids from Halley's Comet?
Yes, as are the Eta Aquariids in May. Earth crosses Halley's orbit twice a year.
Why are the meteors so fast?
The comet orbits against the flow of the planets, so the grains meet the atmosphere almost head-on.
Do I need to look at Orion?
No. Look at any wide part of the dark sky and the meteors will find you.