The Perseids: A Meteor Shower
Shooting stars fascinate the general public and can inspire more than one amazed observer to take up astronomy. This spectacular celestial phenomenon is due to dust from asteroids or comets that the Earth passes through. The Perseids are among the oldest recorded meteor showers. They are also one of the most magical phenomena of the year. Get ready to be dazzled: you can observe them in August!
What are the Perseids?
Among the different astronomical phenomena that can be admired in the summer sky, one of the most famous is the Perseid meteor shower.
The Perseids are shooting stars visible from Earth. Each of these luminous phenomena accompanies the entry of an extraterrestrial body or meteoroid into the Earth's atmosphere.
The dust grains enter the atmosphere at about 59 km/s. They burn up and become luminous at an altitude of 115 km down to about 90 km, then they extinguish.
What is the origin of this celestial phenomenon?
Shooting stars have two origins. When they are sporadic, they are asteroid dust entering the atmosphere. But when they come in swarms, like the Perseids, they are caused by dust from comets that the Earth passes through.
More specifically, the Perseids come from debris of the Comet Swift-Tuttle, identified in 1862.
The name of this Comet refers to the two astronomers who observed it: Lewis Swift and Horace Parnell Tuttle.
Why the name Perseids?
The name Perseids was given to this astronomical phenomenon because the trails of the meteor shower seem to originate from the constellation of Perseus located in the Northern Hemisphere.
These meteor showers also have another more poetic name: The Tears of Saint Lawrence. Indeed, the feast of Saint Lawrence of Rome is set on August 10th, approximately when this phenomenon can be observed with maximum intensity. More than 100 meteors per hour on average are observed during this period.
The earliest writings mentioning these meteor showers date back to the year 36 in China. In Europe, the oldest written records date back to 811. Starting from 1779, systematic observations were made, but it took more than a century for Giovanni Schiaparelli to identify the origin of the phenomenon: the debris of Swift-Tuttle, their orbit being roughly the same.
When are the Perseids?
The Perseids are visible in the northern hemisphere during the summer season and more precisely in the month of August.
Each year, the debris from Swift-Tuttle encounters the Earth's atmosphere from July 17 to 20 and the phenomenon continues until around August 25.
One can then see meteor showers in the sky with the naked eye, with a peak between August 11 and 13.
How to Best View the Perseids?
The trails of shooting stars are clearly visible in the night sky. However, if you are looking for optimal viewing conditions, note that a clear sky, without clouds, without the moon, and with as little surrounding light as possible is ideal for seeing the Perseids well.
Choose a location far from cities and light pollution in general. To determine if the place is suitable for observing this phenomenon, locate the stars of the Little Dipper.
The best time to see them is after midnight, ideally between 1 AM and 3:30 AM. Unfortunately for early sleepers, at the beginning of the night, the meteors are too low to be visible.
To conclude, here are some tips for photographers to remember:
- A very dark sky (therefore far from large cities)
- Patience
- Prefer a 50 mm lens or wide-angle (Maximum aperture/ Focus at infinity)
- Fix your camera on a tripod
- Try long exposures of 5 to 10 minutes with the camera pointed towards the region of the sky where you can observe the phenomenon.
If you're a bit lucky, you'll capture the shot of a shooting star crossing the field during the exposure time.
