It’s that time of year again! The Perseid meteor shower, which peaks this week, is eagerly awaited by observers who hope to enjoy the spectacular sight of several meteors raining down on balmy summer nights.
Perhaps you prefer to gaze at the sky for Perseid meteors, or perhaps you let digital technology record the extravagance instead. You might be looking forward to sharing the Perseid viewing experience with a group of astro-society friends, or for you, meteor watching might be a chance to find inner peace and loneliness under a sky strewn with stars. Whichever way you choose to look, and whether you’re there for the science or just for the fun of it, the Perseids have something for everyone.
Where did the Perseids come from?
As comets make their way through the inner solar system, their surfaces are heated by the warming sun and they become more active. Some of the cometary material is lost and particles ejected, which over time have propagated along the comet’s orbit around the Sun. When Earth crosses this stream of particles, a number of them enter our upper atmosphere, vaporizing to form the trails of light that we see as meteors.
Each meteor shower is linked to a “parent comet”, periodic comet 109P / Swift-Tuttle being associated with the Perseids. This comet has a period of 133 years and last returned to the inner solar system in 1992. Increased rates of Perseids were observed in the early 1990s, which corresponded to this return. Higher Perseid activity was last seen in 2016, although astronomers do not predict high rates for 2021.
No Moon this year!
It promises to be a good year for the Perseids as the pesky moon will not interfere with sightings. It is a new moon on August 8 and it reaches the first quarter on August 15. The Perseids have extreme activity from July 17 to August 24, with meteor rates expected to peak between 7 p.m. and 10 p.m. UT (8 p.m. and 11 p.m. BST) on August 12/13, although some sources cite the maximum occurring later in 02h UT (3h BST).
Reports are already pouring in on Perseid activity, including NASA cameras capturing more than a dozen Perseid fireballs across the United States on the night of August 5.
When to look and where to look
The most profitable nights to research Perseids are August 11/12 and 12/13, but you have to be prepared to stay awake until after midnight and into the early hours of the morning or longer if you want to see your fair share of. meteors. The crescent moon sets at 10 p.m. BST on both nights.
During all meteor showers, the falling stars belonging to the rain (that is, non-sporadic or random meteors, which occur frequently every night) can be attributed to an area of the sky called the radiant. The Perseid radiant is at the far north of Perseus (see graph) and sits low in the northeastern sky at nightfall, climbing to a decent elevation of around 50 degrees at 2 a.m. At this time, the areas of the sky where the Perseids are more likely to spawn will be much better placed than before midnight.
To increase your chances of seeing the most Perseids, don’t look closely at the spot in the sky where the beaming is located, although this advice may seem counterintuitive. The Perseid meteor trails or trails here will appear short and therefore more difficult to see. You will see many more shooting stars if you observe an area of the sky 30-40 degrees from the radiant (hence meteor trails may appear longer) and about 50 degrees above the horizon.
How many shooting stars will I see?
One can never be completely accurate when it comes to predicting observed meteor rates for a meteor shower. On an average year, assuming a cloudless and haze-free sky over a dark observation site, observers can expect to see between 50 and 70 Perseid meteors every hour near the summit. In cities, the rates observed can still be of the order of ten per hour in the early morning when the radiant heat is high.
The Perseids are renowned for producing an abundance of bright meteors and fireballs which often leave lingering trails or trails, although they always produce more faint meteors than bright meteors; this is where watching under dark skies really pays off. The Perseids produce rapid meteors, entering the upper atmosphere at 60 km / second.
It will pay off to do some research beforehand to find a good site from which to observe if your back garden or usual location has a poor view to the east. No matter where you are observing from, make sure you have a comfortable viewing position – a lounge chair or lounge chair is a good choice – and if you can, adjust to the dark for at least 15 to 20 minutes before starting a meteor watch.
Hopefully a clear sky!