There’s currently a whole lot of streaking going on at the University of Virginia and around the globe.
No, we’re not talking about that kind of natural display. Look up! The annual Perseid meteor shower has begun.
UVA Today asked Matt Pryal, an assistant professor in the UVA Department of Astronomy, to give readers the lowdown on the dazzling deluge of sparking space debris and how best to view it.
Q. Why do they call it the Perseid meteor shower?
A. Meteor showers in general are named after the constellation from which the meteors associated with it appear to radiate or travel away from. In the case of the Perseids, they appear to radiate from the constellation Perseus, named for the Greek mythological hero.
A common misconception when trying to observe meteor showers is to expect the meteors to be visible within the constellation that bears its name, but that’s not necessarily the case. The meteors can actually be visible all over the entire night sky.
What you will find, though, is that if you drew lines of light from the meteors on a sky map, and extended those lines across the whole sky, they would intersect near the Perseus constellation.
Q. What causes the meteor shower to keep coming back?
A. Annual meteor showers are the result of the Earth passing into debris left behind by a comet or asteroid that previously passed through the inner solar system. In the case of the Perseids, the comet culprit is Swift-Tuttle, which orbits the sun every 133 years and was last seen in 1992.
In general, the more debris there is, the more spectacular the meteor shower. That debris stays in the same orientation with respect to the sun and stars, and so every year the Earth will pass through that material, causing some of it to burn up in the atmosphere to create those beautifully streaking meteors.
The location of the debris with respect to the stars also determines which constellation the meteors will radiate from.
A more familiar example is when you’re driving through a windless snowstorm: You’ll notice it still appears as if the snowflakes fly by your car, almost as if they’re radiating from a spot just in front of your vehicle. Well, the giant space car we call Earth creates this exact same phenomena as it passes through that space debris.
Q. Is there anything different about the occurrence this year?
A. It’s a bit tough to predict exactly how many meteors will streak hourly during the peak of a meteor shower, but historically they’re fairly consistent year to year in the number of debris that burns up. The biggest factor that affects the visibility of that burned-up debris, apart from clouds, is the moon phase. We’re very lucky this year that the peak of the Perseids lines up nicely with a nearly new moon. This means that if clouds cooperate, we should get a pretty good show.
Q. When can the meteor shower best be viewed?
A. The days surrounding the predicted ‘peak,’ Aug. 12-13, are the best time for viewing. But I would recommend going outside any clear night from Aug. 10 to Aug. 15 or so.
Those who are more ambitious should go out in the pre-dawn hours of those dates, when the shower has historically put on its best show.
Q. Do you have any tips for optimal viewing?
A. Again, you don’t have to look just at Perseus and should be able to see meteors all over the sky. When I watch meteor showers I often look generally in an area between the radiant point –Perseus – and a point directly above head, what astronomers call “zenith.”
Perseus will be located in the northeast area of the sky, and so I’d scan between northeast and zenith.
The real trick is to just dedicate some time and look. In my opinion, the only proper way to stargaze is lying down. So grab a blanket, head to the darkest site you can and take in the universe.
Q. Anything else readers should know?
A. Oftentimes, websites will report a number of meteors you might see for a given shower. Those figures are going to be higher than the actual number the average person will see.
In the case of the Perseids, these estimates can sometimes get on the order of 100 meteors an hour. Such numbers require moonless nights, with no light pollution and unobstructed views, which we do not have in the Charlottesville area.
You should temper your expectations a bit and expect to see on the order of 10 to 20 meteors an hour during peak time, assuming you’re lying down and doing nothing but looking up.