A meteor shower occurs when lots of meteoroids enter the Earth’s atmosphere one after the other. Meteoroids are bits of dust and rock from comets that are released when their orbit brings them close to the Sun. The Sun’s heat boils off some of the comet’s icy surface and the resulting debris then trails it in orbit.
Meteoroids that enter the Earth’s atmosphere are known as meteors, and can regularly be seen travelling across the sky alone. However, several times each year, the Earth’s orbit crosses with the orbit of a comet causing it to collide with a bunch of meteoroids all at once.
Meteors travel through the Earth’s atmosphere at very high speeds – up to 72 kilometres (45 miles) per second. Friction of the atmosphere causes the meteor to heat up so the cloud of gas around it glows, and it’s this that we see shooting through the sky. As they are usually very small, most meteors burn up in the atmosphere before they reach the Earth’s surface, but those that do occasionally hit the ground are known as meteorites.
Meteor showers are named after the constellations they appear to be falling from, so the Orionids shower comes from the Orion constellation.
Orionids occurs every year around 20-22 October when Earth passes through the orbit of Comet Halley. This sendsaround 10 to 20 meteors per hour streaking through the sky, travelling at around 66 kilometers (41 miles) per second.
In 2015, the Orionid meteor shower is expected to reach its peak in the early hours of the morning on 21 or 22 October, but meteors may be visible the night before and after too. For your best chance of seeing them, find a dark location with minimal light pollution and look up. If you don’t see anything right away then don’t be disheartened. Meteor showers often occur in spurts, sometimes with up to an hour passing between sightings, plus it can take your eyes a while to adjust to the dark.
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