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KNAU and Arizona News

Stargazers may see unusual “meteor storm” tonight

A dark sky is lit up with streaks of bright light.
NASA/JPL
An outburst of Perseid meteors lights up the sky in August 2009 in this time-lapse image.

Astronomers say a regular meteor shower tonight may turn into a spectacular “meteor storm” with a thousand of shooting stars per hour or more. That’s due to a dense cloud of dust left by the breakup of a comet decades ago. KNAU’s Melissa Sevigny spoke with Lowell Observatory astronomer Nick Moskovitz about why the event could be a downpour of meteors…. or just a drizzle.

Tell me about this particular meteor shower. It’s one that most of us have never heard of, I think.

That’s right. It’s a meteor shower that few people have heard of before this year. It’s a shower known as the tau Herculids. That’s because the point in the sky where the meteors look like they’re coming from is in the constellation Hercules. It is an annual shower, but it’s typically a pretty mundane annual shower. Something like 5-10 meteors per hour would be a typical year, so you would barely notice it if you were to go out and watch. This year it could be a little different so that’s part of the reason people are getting excited about it.

So why is this year different?

This annual shower, like any annual shower, is caused by the Earth passing through the stream of particles associated with a particular comet. In the case of the tau Herculids, the parent comet is a comet known as Schwassmann-Wachmann 3 or Comet 73P. In 1995, Comet 73P had a big outburst. It broke into several pieces. That outburst released an unusually large numbers of particles in 1995.

So it’s taken the Earth a couple of decades to catch up to this big cloud of particles.

That’s exactly right, and that’s often the case when we’re talking about meteor shower outbursts, and things like that, you don’t necessarily see them right after they happen, you wait for the Earth to catch up to that cloud of stuff in space, and that’s exactly what happening here.

A lot of things in the night sky, astronomers are able to predict very, very accurately. It sounds like this is a little trickier. This is more like predicting the weather, you’re not sure what’s going to happen.

That’s absolutely right. That’s a great analogy. Meteors showers, and the streams associated with generating those meteors showers, are really hard to predict…. So that makes it exciting. That’s a fun part of astronomy, when you don’t know the answer ahead of time, you’ll find out and whatever happens, we’ll learn something about how that particular outburst and meteor shower have evolved over the past 20 years…. The unpredictability of it is a thrill. But it’s also a fantastic area of science because anyone can participate in it. It doesn’t involve fancy telescopes or fancy equipment; your eye is still the best instrument for observing meteors…. I’ll be out, looking up and seeing what happens, because if it does turn into a spectacular show, it’s a once in a lifetime opportunity, so it’s worth taking the hour and hanging outside for a little bit.

If it turns out to be a good year, what might people see in the sky?  

There’s a wide range of predictions coming out related to this shower. Some predictions would suggest slightly enhanced activity for this shower, which might mean 10 or 10s of meteors per hour…. The more extreme models suggest much higher levels of activity, some as high as a thousand, ten thousand, even a hundred thousand meteors per hour. Now that’s as I say, one set of calculations that suggest an extreme possibly. Again, we don’t know. I think it’s a little bit of a coin toss as to whether it will be an intense meteor shower or what we would call a “meteor storm.” A meteor storm would be a thousand meteors per hour. So essentially every time you look up there’s a meteor. It’s a coin toss as to whether it will become a storm or not. I will definitely go outside and look up, but it’s not a guaranteed thing.

Okay, fingers crossed it’s going to be good. Nick Moskovitz, thank you so much for speaking with me.

A pleasure, thank you.

How to see it:

The meteor shower is expected to peak between 9 and 10pm Mountain Standard Time and could last for as long as two hours. The shower will be dominated by small shooting stars radiating from a point high in the northwest. Skywatchers should find a dark place to watch the show.

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