See the eta Aquarid meteor shower from anywhere. Here's when
Monday, May 2, 2016, 1:57 PM - Famous Halley's Comet is bringing a pre-dawn meteor shower to our skies on Thursday and Friday, and here's how you can watch it from anywhere, no matter what the weather is like.
Twice every year, Earth's orbit around the Sun carries it through streams of debris in space, left behind by the passing of Comet Halley. When the the tiny flecks of dust and ice that make up these streams plunge into Earth's atmosphere, they are moving fast enough to produce glowing trails through the sky, resulting in meteor showers.
On the mornings of May 5 and May 6, we will be able to see the first of these two Halley's Comet meteor showers - the Eta Aquarids.
Watch from anywhere
The meteor shower's radiant - the point in the sky where the meteors appear to emerge from - rises along with the constellation Aquarius, in the very early morning hours. The meteor shower should be visible from about 3 a.m. local time, until dawn, on both mornings.
The eta Aquarid radiant in the eastern sky, at 4 a.m. on May 5 and May 6, 2016. Credit: Stellarium/S. Sutherland
While it's not considered one of the strongest meteor showers that occur during the year, anyone with clear skies and far away from sources of light pollution should be able to see between 10 and 20 meteors per hour.
According to NASA, the morning of May 5 may be the better of the two days for viewing, with slightly more meteors visible in the sky, and the exact peak of the meteor shower is expected during daylight hours on May 5.
Below are maps of the expected cloud conditions for the two mornings (check back for updates to this forecast).
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If the weather fails to cooperate with you on these two mornings, or the timing doesn't really work with your sleep schedule, the Slooh Community Observatory is hosting a live show, which can be viewed via the embedded video at the bottom of this article.
The Slooh show begins at 8 p.m. EDT, on the night of Thursday, May 5.
One of the remarkable things about the eta Aquarid meteor shower is that they can produce what are known as "persistent trains" - colourful, faintly glowing streaks that can persist in the sky from a few seconds to several minutes after the meteor has winked out. Some have even been observed for hours afterward.
What causes this is the exceptional speed of the meteoroids in the stream of cometary debris.
When a typical meteoroid passes through the Earth's upper atmosphere, it's travelling at around 100,000 km/h, and it compresses the air molecules directly in its path to the point where they heat up and glow. This glow persists for as long as the meteoroid exists (the heat vapourizes ice particles and smaller bits of dust) and as long as it's travelling fast enough to continue compressing the air (since the compressed air pushes back against the meteoroid, slowing it down).
The particles in the eta Aquarid stream hit Earth's atmosphere travelling at more like 240,000 km/h. This produces the bright meteor flash, and sometimes there's an added bonus.
After the meteor has winked out, a glowing trail can be left in the air.
Since these have only rarely been recorded, there's still some uncertainty about exactly how this is caused, however there are two basic ideas behind this effect. The first says that the meteoroids are travelling fast enough to actually strip electrons from the air molecules, ionizing them. As the air molecules reclaim those liberated electrons, the energy they release in the process is emitted as light. Since this process can take much longer than the original meteor flash, the "train" persists in the air afterward. The second says that metals vapourized off the fast-moving meteoroids chemically react with ozone and oxygen to produce the glow via chemiluminescence. One of these explanations may account for these "trains" or both may cover different occurrences, at different times, and even between individual meteors.
It will take more sightings of these to fully explain them.
Sources: NASA | Slooh | With files from The Weather Network
Watch Below: The Slooh Community Observatory eta Aquarid show starts at 8 p.m. EDT, Thursday, May 5.