Every year, mid-August brings the peak of the Perseid meteor shower, making for a fantastic opportunity to see and photograph a usually high rate of bright meteors and fireballs. These meteors are actually fragments of comet Swift-Tuttle meeting their fiery end at about 55 km per second in the upper mesosphere.
The Perseids are active from mid July until late August, and appear to originate from a region in the Perseus constellation, which reaches its highest elevation during daylight hours.
It’s therefore more favourable to observe after midnight across the peak dates.
The oft-quoted Zenithal Hourly Rate (ZHR) of the Perseids is usually between 100-110, but the ZHR is something of an ideal figure to illustrate the relative performance of a meteor shower.
It equates to how many meteors one might expect to see under absolutely perfect conditions when the radiant – the point from which the meteors seem to emanate – is directly overhead.
Real rates will always be much lower.
John Elder took this image of a Perseid streaking across the Milky Way. John used a Canon EOS 60Da DSLR camera.
Credit: John Elder
So you’re ready to catch some Perseids, but what should you bring?
There’s no advantage to zeroing in closely on any particular region of the sky (unless you’re counting on being extremely lucky!) so binoculars and telescopes won’t be necessary.
Your eyes are the best meteor-watching equipment you could hope for, quick at spotting transient flashes of light over a huge field of vision.
Keep in mind that spotting Perseids can be addictive and lead to long sessions outdoors.
Although August nights are some of the kindest of the year, be prepared to stay out well after midnight with appropriate clothes, food and drink so you don’t get caught out.
Lying on a deckchair will protect your neck from the kind of cramps only meteor showers can produce.
It’s one thing to enjoy a thrilling night of Perseids, but you could go a step further and top it off by bringing the home photographic evidence to show your less adventurous friends.
With a bit of preparation, you can set up a relatively hands-free photography station to monitor the sky for you.
Kevin Lewis composed a beautiful image of the Milky Way over St. Cwyfan Church on the island of Anglesey, and managed to also capture a Perseid in the frame! Kevin used a Canon EOS 5D Mark III DSLR camera and 24-70mm lens.
Credit: Kevin Lewis.
Tips for photographing the Perseid meteor shower:
DSLR cameras offer the most flexibility for wide-field photography of the sky.
Interchangeable lenses allow you to select the best equipment for the job.
Narrow fields of view will lower the likelihood of capturing a meteor in any given exposure, so use your widest lens on its widest setting. Focal lengths between 10-24mm are ideal.
As with all low-light and time-lapse photography, a tripod is essential.
Better yet, you can use compact equatorial tracking systems designed for light payloads to keep your stars nice and sharp over long exposures.
Use an intervalometer to do the boring bit
Taking continuous exposures back-to-back with a large area of sky in view can be hard work, so this valuable piece of photographic kit should make the session more enjoyable.
Make sure your memory card has plenty of space, and set your camera to shoot RAW images.
Focusing on stars can be tricky
Most cameras have a liveview zoom feature, allowing you to manually focus until a bright star appears as pin-sharp as possible.
Bear in mind that most lenses focus ‘beyond infinity’ for mechanical reasons, so you can’t rely on the focus dial entirely.
You’ll also find that stars at the edge of the field appear much less point-like, but the edges can be cropped out later.
Experiment with exposure settings
Test out your camera and play about until you get pleasing results for your local sky conditions and camera/lens combination.
Most cameras give best overall long exposure results between ISO 800-3200, but how bright your photo appears will of course depend sensitively on the exposure time and the photographic speed of the lens.
If your lens is wide, with a maximum aperture of F/4 or faster, you can rely on 15-30 second exposures to produce sharp stars on a static tripod, whilst ensuring meteors in view will be conspicuous in the final image.
Controlling the sky brightness in light-polluted images should also be a consideration, as a blown-out sky will reduce the contrast of fainter meteors.
Target the highest ratio of exposure to on-board camera processing
And keep the delay between images as short as possible.
Consider turning off your camera’s on-board long-exposure noise reduction to increase the rate of images you can take.
Fewer images means a lower likelihood that your camera is gathering light at the critical moment that a brilliant fireball blazes in view. You can take steps to clean up noise with software afterwards.
The Perseids, like any great meteor shower, is an excellent opportunity to capture a unique and dramatic photo for your collection.
Good luck and happy hunting!
If you do manage to photograph a Perseid meteor, be sure to share with us via email or on our Twitter and Facebook accounts.
Tom Kerss is an astronomer based at the Royal Observatory Greenwich