Based on the number of observable meteors that can be seen during its active duration, the Orionids are considered a major meteor shower, which lasts approximately from the first week of October to the first week of November.
The display is now active, and the American Meteor Society estimates that within the next few days, a handful of meteors every hour will be visible, leading up to the peak on Oct. 20 and Oct. 21, where the number may climb to 20 every hour.
The word 'meteor shower' might give you the image of a shower to that of rain. But few of these meteor showers resemble rain showers. The Orionids are not the best shower of the year, and storming (producing unforeseen, very abundant displays) is not particularly known. You can see 10 to 20 Orionids per hour at their peak from a dark spot in a year where the moon is out of the way.
If you're lucky to spot any Orionids, note that they are known to be extremely fast meteors, plunging about 66 kilometers-41 miles-per second into the Earth's atmosphere. The meteors are quite faint, but that's what they make up for; maybe half of the Orionid meteors leave lasting trains or ionized gas traces that linger a few seconds after the meteor is gone.
An Orionid meteor may also often be incredibly bright and split up into fragments, and it will emerge from the radiant point of the shower.
Orionid meteors are radiating from the Orion constellation. In annual showers, meteors are named for the point in our sky from which they seem to radiate. In the direction of the prominent constellation Orion the Hunter, which you will find rising to the east in the hours after midnight, there you will see the radiant point for the Orionid, which is where it got its name.
In order to see the meteors, you don't have to recognize Orion or be looking at it. Meteors often do not become visible until their radiant point is 30 degrees or so. And note that they streak out from the radiant in all sorts of directions, so you're likely to see them in all parts of the heavens.
The Orionid meteors are the debris left behind by the most famous of all comets, Comet Halley, which last visited Earth in 1986. This comet leaves debris in its wake that most fully hits Earth's atmosphere around October 20-22, when Earth intersects the orbit of the comet, as it does at this time every year.
