Every year in early August, we can observe the Perseid meteor shower (“the Perseids”). And it’s a fascinating sky event.
Here’s a beginners’ guide to what it is and how best to enjoy it. (Perhaps, impress your friends with these astronomy questions and answers!)
What are the Perseids and what is a meteor?
Every year in August, the Earth passes through rock and dust fragments left behind by the comet Swift-Tuttle, last time it came near the Sun. As these small particles collide with the Earth’s atmosphere, they burn-up, often creating a startling streak of light across the sky.
You can easily observe this and it can be a wonderous spectacle.
Why is it called the Perseid meteor shower?
The term “Perseid”, refers to the star constellation of Perseus.
View of Perseid meteor radiant point, above NE horizon after midnight
The meteors actually have nothing to do with the stars we see from Earth, as being part of Perseus. It just appears as though the meteors originate from Perseus.
In fact, the rock fragments are close to the Earth – that’s why they burn in our atmosphere.
They are very close, just a few hundred miles – not many, many light years distant like the stars.
But, if you trace-back the bright trails of meteors we see, they appear to originate from the stars of Perseus.
When can you see them?
The Perseid meteor shower actually starts in late July and runs to late August. However, the best time to view is around the peak.
It’s not precise, but the 2009 peak is expected on August 12th at around 15.00 hours UT. There is some uncertainty, so it’s very worthwhile to observe either side of this.
In particular for European observers, the hours of darkness either side the peak hours, may well prove more fruitful! So try the previous Tuesday night, as well as the night of Wednesday 12th.
And there is also a potentially prominent Moon to contend with. It will not set below the horizon until the early hours of the morning.
What equipment do you need to observe the meteor shower?
The good news is none! Just use your eyes.
It will help your observation if you give your eyes some time (say 15 minutes), to become adapted to the darkness.
Binoculars my also help, but on the other hand, they may restrict your view to a small part of the sky.
The meteors originate in the region of Perseus, but they may appear in view just about anywhere in the sky. Although, if you were to track-back their trails, you would get to Perseus.
Can they be measured, at all?
Yes. Keen astronomers count how many appear in a fixed period of time, in a certain area of the sky. This is expressed as a Zenithal Hourly Rate (ZHR).
We may expect around 100 streaks of meteor light across the sky per hour, at or near the shower peak.
Do watch out for them on Wednesday 12th August and during hours of darkness, before and after.
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