Every year two meteor showers occur as a direct result of the Earth passing through the dust that is released by Halley’s Comet: The Eta Aquarids and the Orionids, aptly named for the point inside the constellation Orion from whence the meteors appear to radiate.
Beginning around 15 October and ending around 29 October, the Orionid meteor shower is usually at its maximum during the early morning hours of 20 – 22 October.
Many thousands of years ago, Halley’s Comet left a trail of dust behind as it traveled through space. The Orionid meteor shower occurs when Earth travels right through that path of dust and debris. What appears to be shooting stars are merely tiny grains of dust vaporizing in Earth’s upper atmosphere.
Bill Cooke of NASA’s Meteoroid Environment Office says that:
“Flakes of comet dust hitting the atmosphere should give us dozens of meteors per hour.”
The Best Viewing
During the beginning of the Orionid meteor shower and again at the end, the Orionids themselves are hardly noticeable in the night sky. However, during its maximum, viewers in the Southern Hemisphere could possibly see up to 40 meteors per hour, whilst Northern Hemisphere viewers will see around 20 meteors per hour
The Orionid meteor shower will starts its maximum tonight and therefore the best time to watch, regardless of where you live, will be between 1am and dawn local time on Wednesday morning.
According to Space.com, this is possible because:
“That’s when the patch of Earth you are standing on is barreling headlong into space on Earth’s orbital track, and meteors get scooped up like bugs on a windshield.”
When the Earth enters the deepest part of Halley’s Comet’s dust, it will mark the beginning of the peak activity period of the Orionid meteor shower. This will probably occur at approximately 6am or 3am PT.
A few stray meteors could also be visible earlier tonight as well, although those people living in cities will see less meteors overall than those people living in rural areas. This is because light pollution in the cities will obscure the meteor’s brightness.
The Best Shower
According to Cooke, the Orionid meteor shower is one of the best showers to view:
“Since 2006, the Orionids have been one of the best showers of the year, with counts of 60 or more meteors per hour.”
However, actually predicting meteor showers is hard as the debris can stem from multiple streams. For instance, every time that Halley’s Comet travels around the sun on its elongated orbit, which is usually every 76 years, it actually leaves behind a new path of debris for the Earth to move through in the years to come. This pathway eventually starts to spread out over time and the Earth then passes through it every October during the Earth’s 365 day trek around the sun.
The past few years has seen more meteors during the Orionid meteor shower than ever before. Mikiya Sato and Jun-ichi Watanabe, researchers from Japan, believe that this is due to debris stemming from 1266 BC to 911 BC. NASA believes that this will be another good year to view the Oroinid meteor shower.
For many years prior to 2006, the Orionids reliably produced 15 to 20 meteors per hour at their peak which were easily visible for viewers under dark skies.
As luck would have it, there will also be about 5 to 10 meteors per hour during this peak period that are not related to the Orionids at all! These meteors will be much weaker and more sporadic than the Orionids.
The Orionids will move relatively fast. But the easiest way to distinguish an Orionid meteor is to trace it backwards. If it leads you back to the Orion
constellation, then you know that it was an Orionid meteor.
The discovery of the Orionid meteor shower has been credited to E. C. Herrick of Connecticut who, in 1839, was the first person to state that there was meteor activity around 8 – 15 October each year. In 1840 he made the observation that the “precise date of the greatest meteoric frequency in October is
still less definitely known, but it will in all probability be found to occur between the 8th and 25th of the month.”
However, on 18 October 1864, A. S. Herschel made the first accurate observation of the meteor shower, when it was seen that 14 meteors radiated out from the Orion constellation. A few days later on 20 October 1865, Herschel confirmed the sighting of a meteor shower originating from Orion.
Since then, the Orionids have become one of the most observed annual meteors showers.
Photo Credit: makelessnoise