What is the Perseid meteor shower?
Impress your pals with some quick-fire meteor facts
Visible this week (pending clear skies) and with up to 100 meteors per hour at its peak, the Perseid (pronounced ‘per-see-id’) meteor shower is one of the most impressive annual events in the celestial calendar.
So while you’re staring into the abyss in awkward silence with your fellow stargazers, it might be useful to have a few meteor facts to hand once the inevitable cosmic pondering starts.
What is a meteor shower?
Meteors are high-speed space rocks made up of dust and particles left behind by comets. When Earth passes through comet debris (in this case, the Swift Tuttle comet), debris burns up as it enters Earth’s atmosphere. Since the Earth keeps orbiting the sun, we plough into the same cloud of comet dust at the same time every year.
What is a comet?
Comets are large objects made of dust, gas and ice that slowly orbit the Sun. They’re what’s left over from the formation of the solar system roughly 4.6 billion years ago. Usually found way out in the solar system, they take a much longer route to orbit the Sun — as long as hundreds of thousands of years. Swift Tuttle’s orbit takes around 133 years.
Fun fact — NASA scientists call comets ‘dirty snowballs’ or ‘snowy dirt balls’ depending on their make-up.
Not-so-fun fact — At 16 miles wide, the Swift Tuttle comet is actually a potential threat to Earth. A close encounter with our planet is predicted for the year 3044.
Do meteors actually hit Earth?
Once a meteor hits the ground on Earth, it’s called a meteorite.
But most of the meteors you’ll see in a meteor shower are no bigger than a grain of sand — the brighter ones might be a few inches long. So if they do survive the journey you’re unlikely to ever find them. Scientists have had better luck spotting them out in the snow in Antarctica, and can make estimates about how many land elsewhere — about 17,000 every year. Big meteorites are pretty rare, though. The biggest ever discovered is the Hoba meteorite. Hoba is around 9 feet in length, but weighs a staggering 60 tons. It’s thought to have landed 80,000 years ago.
The light show in the sky
The meteors you’re seeing when you observe the Perseids are travelling at about 36 miles per second, and as they burn up in the Earth’s atmosphere (virtually everything would at that speed) they light up, leaving a fleeting trail in the night sky.
Where did they get their name?
Perseus was a Greek mythical hero and slayer of monsters who famously beheaded Medusa (the one with snakes for hair). The meteor shower appears to come from the general direction of the constellation Perseus, hence the name Perseids.
What if the dust cloud runs out of debris? No more meteors?
Swift Tuttle last passed by Earth in 1993, leaving behind the debris we now pass through each summer. The debris field gets replenished each time the comet completes a loop — it’s due back in 2125. But there’s a good chance the meteors you’re seeing in 2024 were left there thousands of years ago. The Perseids have been observed for around 2,000 years and the rate of meteors per hour hasn’t changed all that much. It’s here to stay.
Is it the best meteor shower to see? Or is there a better one?
It’s generally thought of as the second best in terms of brightness and frequency of meteors. It’s chief rival for that title is the Geminids, but occurring in the dead of winter (mid-December) it’s less fun to hang out in a hammock at midnight to watch them.
Catch the Perseid meteor shower as it peaks the evening of August 12. Head out to areas free from light pollution between about midnight and sunrise for the best results!
