The Perseid Meteor Shower – so called because the meteors all appear to radiate from the constellation Perseus – is one of the best shows in the astronomical calendar.
It’s popularity is probably due to the fact they are easy to observe, visible from anywhere in the Northern Hemisphere, and being in the Summer months means we are not wrapped up in lots of thermal layers!
The source of the Perseids is the comet 109P/Swift-Tuttle. This comet takes 133 years to orbit the Sun and it’s last visit was in 1992 – it will be 2125 before it visits us again!
Although discovers in 1862 by Lewis Swift and Harace Tuttle, it was Giovanni Schiaparelli in 1865, who figured out that this comet was the source of the Perseid shower.
As the comet makes its way around the Sun, it leaves a trail of dust debris and as our Earth makes its orbit, it crosses this trail of dust. As the dust particles collide with our atmosphere, the burn up, causing the streaks we know as meteors or shooting stars. The bigger the grain of dust, the brighter the streak!
How to View
This year, the bright full moon is going to interfere with the show – many of the smaller ones will be lost in the glare of the moon. However, it possible to see some, with a little but of careful planning.
The best time to see Perseids is after midnight, as the constellation of Perseus rises in the North East. Find somewhere away from house and street lights and try and position yourself so that the glare of the moon is as blocked as possible.
For the really best views, wait until Perseus rises higher in the sky – around 3am. The Moon will set around 3:40am, and although the glare will be present, is much less interfering.
How many will I see?
Every meteor shower has a ZHR – Zenith Hourly Rate. This is the supposed number you would see under clear dark skies, with the radiant directly overhead at the Zenith. The Perseids is quoted at 110 per hour.
Unfortunately, these numbers are often misquoted by the media and the public are led to believe they will see 100’s of meteors literally raining down on them! Not quite so….
Given the interference from the moon, and light pollution, you will see far less than this. The further you are away from light polluted areas, the more you will see, but it will still be in 10-20 per hour range.
What about using a camera?
Camera’s offer a great way to record the meteor shower! Here are some tips…
- Mount your camera on a sturdy tripod, and aim it North East
- Use a wide angle lens and set the aperture as wide as possible (low f/ number)
- Set the ISO level to around 800 – 1600
- Set the exposure to 15 seconds
You may need to adjust the ISO or exposure time to not wash out the sky or make the camera a little more sensitive to capture the stars.
if you have one, use an intervalometer to program the camera to take repeated exposures – or use a release cable.
Hopefully, you’ll capture some great streaks in your images – and remember to submit them to BAS so we can show them off!