Everything You Need To Know About The Perseid Meteor Shower

The Perseid Meteor Shower is one of the most reliable and best meteor showers of the year alongside the other giant, the Geminid meteor shower in December. The Perseids usually peak each year in August but will be visible even as early as mid-July. This is definitely something you don’t want to miss.

Peak Rate
Between August 10-13 expect a rate of around 80 meteors/hour provided you have a dark sky. Perseids will be visible (though fewer) even in mid/late July as it builds up. The Perseid shower will combine with the Delta Aquarids as well, which peak around July 28 but are active until early August. The Delta Aquarids are less spectacular than the Perseids and this year the Moon will be brightening up the sky during their peak, but you may still see a few around that time. The Delta Aquarids radiant point (Aquaris constellation) allows for a better show in the Southern Hemisphere.


(Perseid meteor in 2011 as seen from the ISS, taken by Ron Garan)

— Light Pollution
To ensure you see the most meteors possible, go somewhere away from city lights and get atop a mountain if there is one near you, as this will minimize light pollution. 
The light pollution from a city (or the moon!) will drown out fainter meteors, so best to avoid that. As you can see in the second image here, light pollution lowers the amount of stars you can see in the sky AND the meteors/hour rate. Have you ever seen the Milky Way with your own eyes? It’s amazing, you should definitely try to find some dark sky to view it. In some places it’s bright enough to cast shadows!

Thankfully the moon sets in the afternoon, before midnight, during the time of the peak so it won’t ruin the show. It is only a crescent (about 17% illuminated) on the night of the 10th but will be around 45% illuminated on the 13th and set later in the day then as well. Once the moon sets, typically the best time to watch will be the hours just before sunrise, though it should be a good show all throughout the night either way. Now we can only hope to have clear skies.

Radiant Point
Meteors will appear all across the sky (so don’t restrict yourself to looking at just the Perseus constellation), however they will seem to radiate from the Perseus constellation, meaning their tails will point back towards it. Just lay back and scan the sky, and when your eyes adjust to the darkness you will be able to see more.

Perseus rises in the Northeast, located near the Pleiades star cluster and the “W” shaped Cassiopeia. [See the radiant point as seen from the Western and Eastern US]. (Images made using Stellarium)
Perseid Radiant as seen on the night of the 11th from Western US

More meteors will be visible when the Radiant point is higher in the sky, because when the radiant is low only meteors traveling at the correct angle will be visible as there is more atmosphere for it and the light to travel through making them further away and also more dim. When it is higher, the meteors are traveling through less atmosphere, scattering the light less, making them brighter. Also more of the sky is scooping up comet-dust, increasing the rate.

The illustration below makes it seem as though some parts of the world might not see the shower but the only thing you have to worry about is your latitude because the comet debris field is large enough for Earth to spend a few weeks traveling through.

— Visibility
The radiant location also means the Southern Hemisphere will see lower rates. Areas below -32 degrees latitude will see very few to none because the radiant point never rises above the horizon. I recommend taking a drive north if you live close to or below that latitude. [Full Size]

The red line is -32 degrees latitude. Around and below that area will have low visibility.

Something to note, when the radiant point is near the horizon you will see less meteors - as was mentioned before - but you will also have a chance to see more Earthgrazers. These are long-lasting meteors that cut across Earth’s atmosphere at a less steep angle leaving long tails behind them [like this one in 1972]. They can be quite spectacular and if the space rock is large enough it could even pass through Earth’s atmosphere and back out into space!

Notes

The background art for the first image before editing was made by Mark A. Garlick // Space-Art

Dark Sky Finder // Help map global light pollution

Rate Estimator (Fluxtimator) // Meteor Counter App for NASA Research

Stellarium or Planetarium

Just sit back, find somewhere dark, take in the majesty of the cosmos and ride spaceship Earth through the debris field of comet Swift-Tuttle at ~107,000kmh. Be sure to bundle up, stay warm and remember; you might see a lot or you might not see many, but if you stay in the house, you won’t see any.