Sunday 30 July 2017

Fireball meteor over Washington State.

The American Meteor Society has received reports of a bright fireball meteor being seen over Washington State, slightly before 10.00 am, Eastern Daylight Time, (slightly before 4.00 am GMT) on Saturday 29 July 2017. The majority of the sightings came from Washington State, though reports have come from Oregon and British Colombia too. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry.

 The 29 July 2017 fireball meteor seen from Lake Tapps in Pierce County, Washington. Marianne Scott Lincoln/King 5.

The meteor was seen to move from southeast to northwest, apparently terminating over the town of Pilchuck in Snohomish County, Washington (such meteors typically terminate many kilometres above the ground in an explosion caused by friction with the Earth's atmosphere). It has been described as greenish in colour with an orange tip to its tail, and burned for about five seconds.

 Map showing areas where sightings of the meteorite were reported, and the route of the object (blue arrow). American Meteor Society.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. It is possible, though unlikely, that this object will have produced meteorites that reached the surface (an object visible in the sky is a meteor, a rock that falls from the sky and can be physically held and examined is a meteorite), though most meteorites come from larger objects that penetrate further into the atmosphere before exploding, and therefore have a better chance of producing fragments that reach the surface.

Witness reports can help astronomers to understand these events. If you witnessed this fireball you can report it to the American Meteor Society here.  

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