It is time to go Perseid meteor hunting! This meteor shower peaks on August 12. Look for streaks of light, often called shooting or falling stars – they can appear anywhere in the sky. They are “space-dust” from Comet Swift-Tuttle, which last made a pass by Earth in 1992. Some of the material of the comet lingers in space, and the Earth moves into it in August of each year.
This year MIGHT feature an outburst – as the Earth moves through a thicker clump of the comet debris. (that was for 2016!) 2017 will be tricky due to the just past Full Moon, lighting the sky during the best viewing hours after midnight. Face north with the Moon at your back for the best chance of seeing fainter meteors.
If you do want to go meteor watching this month here are a few tips:
1: Get comfortable and stay warm! A sleeping bag and a reclining lawn chair are a good idea.
2: Observe from as dark a location as possible and give your eyes 15 to 20 minutes to adjust to the darkness of the sky.
3: Be well rested before observing. Napping before observing is recommended since the best time to observe meteors is after midnight. As the American Meteor Society points out “You certainly will not see much meteor activity through closed eyelids!”
4: Look generally upwards. Above 45 degrees from the horizon the atmosphere is thinner, so any observed meteors will be brighter than they would be if seen nearer the horizon.
5: Look for the colours of the meteors. Many of the brightest meteors take on a strong greenish hue, which is believed to be due to our atmosphere’s oxygen reacting to the passage of the meteor.
Bear in mind that most meteors seen in the course of an observing session are faint ones. Only a small fraction are brighter than magnitude 0 (or as bright as the brightest stars), about one in 1200 becomes brighter than -5 mag (or brighter than Venus at its brightest), while only one in 12 000 reaches -8 mag (over ten times brighter than Venus).
And if you are really fortunate, you can try to hear the meteors! For hundreds of years (going all the way back to the time of Edmund Halley in the 1700s) a fizzing or hissing noise has been reported as being heard simultaneously with the sight of a meteor. These are known as electrophonic meteor sounds and might be linked to low frequency radio waves being emitted by the plasma trails of the meteors. These radio waves travel at the speed of light and can be detected by objects near an observer immediately – without showing a delay from having to travel at the speed of sound. Good detectors include objects like aluminium foil, thin wires, pine needles and even dry or frizzy hair. So if you are going out observing, fluff your hair as well as pulling on warm clothes!
For younger readers: Find out more from ESA Kids.