Orionid meteor shower at a glance
| Detail | Value |
|---|---|
| Activity window | about October 2 to November 7 |
| Peak | around October 21 |
| Zenithal hourly rate (ZHR) | about 20 |
| Radiant | Orion, north of Betelgeuse |
| Parent body | comet 1P/Halley |
| Entry speed | about 66 km/s |
These values follow the International Meteor Organization (IMO) calendar. For all showers in one list, see the meteor shower calendar.
Dust from Halley’s Comet
Comet 1P/Halley orbits the Sun about every 76 years. It last came to the inner solar system in 1986. On each passage, heat from the Sun releases dust and small grains, and over thousands of years those grains have spread along the comet’s orbit.
Earth’s orbit comes close to that stream at two points. In October we pass one side and see the Orionids. In May we pass the other and see the Eta Aquariids. So each year, you have two chances to see pieces of the most famous comet in history.
Fast meteors with trails
Orionid grains meet Earth nearly head-on, at about 66 km per second. That is one of the highest speeds of any major shower. Fast meteors are often bright, and a fair share leave a persistent train, a faint glowing trail that can linger for a second or more after the meteor has gone.
The ZHR of about 20 means a single observer would see about 20 meteors an hour under a perfectly dark sky with the radiant overhead. In practice, from a dark site, 10 to 20 an hour at the peak is typical. Rates vary from year to year; in some years in the 2000s they were noticeably higher than usual.
Where to look
The radiant lies in the northern part of Orion, a little north of the red star Betelgeuse and close to the border with Gemini. Orion rises in the late evening in October and is highest before dawn, so the best hours are from about midnight until the sky starts to brighten.
Because Orion sits on the celestial equator, the Orionids are visible from almost everywhere on Earth. Observers in both hemispheres get similar views.
You do not need to stare at the radiant. Look at a dark part of the sky about 45 degrees away from it. Meteors seen there have longer, more impressive paths.
Moonlight
The Moon’s phase around October 21 can make or break a given year. A bright Moon in the morning sky will hide most of the fainter meteors. Check the moon phases and your local moonrise and moonset times to find the darkest hours. Because the shower’s peak is broad, you can also try a night a few days before or after if the Moon is in the way.
Viewing tips
- Plan for the early morning. The hours after midnight are best, with the radiant climbing higher until dawn.
- Choose a dark, open site. Get away from streetlights and keep a wide view of the sky.
- Let your eyes adapt. Spend 20 to 30 minutes in the dark without screens.
- Get comfortable. A reclining chair, a blanket and warm layers make a long session easier.
- Look for persistent trains. After a bright meteor, keep looking at the same spot for a moment.
- Watch more than one night. The broad peak gives you flexibility with weather and moonlight.
For more about the night sky on any date, see the sky tonight.