WILLIAM BRANGHAM: Parts of the United States have recently been getting glimpses of the Northern Lights.

John Yang spoke with our science correspondent, Miles O'Brien, for a brief explanation of why the spectacle in the skies is now being seen further south.

JOHN YANG: Miles, every year, there is the Northern Lights, the aurora borealis.

But it is usually restricted to the northernmost areas of the Earth.

Now it is coming as far south as the United States.

Why is that happening?

MILES O'BRIEN: So, the sun has a cycle, John, of about 11 years.

It goes from solar minimum to solar maximum.

We're right at about at the maximum or we're approaching it.

And what that means is that the activity on the sun greatly increases.

And it blows particles from the sun in our direction that interact with the magnetic field in our atmosphere and, in so doing, excite them and make them colorful, and, in some cases, green and red colors.

And because we're at this point in time, where there's more of this activity headed our way, we're seeing wonderful aurora borealis, or Northern Lights.

And it is extending a little farther to lower latitudes.

So it's a great opportunity.

If you have never had the chance to see them, by all means, make an effort to do it.

You don't have to go to the Arctic or to Iceland anymore because of this solar maximum.

And what's great about it, too, is, when you go to see them, every time you see them, it's different.

It's a different kind of ethereal thing of green and red lights in the night.

And it's -- it's kind of a romantic thing, actually.

JOHN YANG: Give some advice to people who want to see it.

Obviously, you have to get away from the cities.

You want someplace that's really dark.

Where do you look in the sky?

MILES O'BRIEN: When it's there, it's everywhere.

Try to get as far north as you can.

Like I say, it's coming down into the northern parts of Europe and in places where you wouldn't normally see it in the United States as well.

The thing is to just get up in the middle of the night, and wait and enjoy the spectacle.

JOHN YANG: And how long is this greater activity going to go on?

MILES O'BRIEN: Well, I think solar maximum is going to peak out at about 2025.

And so then it'll start scaling back.

So, in that period of time, this will continue to be quite a light show.

It also has the potential to really cause some difficulties for communication satellites and the power grid, so we should be on guard for that as well.

The sun is a big player in our solar system, to be sure.

And when this solar maximum occurs, it's not just a spectacle.

It's a potential harm to some of our systems.

So we have to watch out for that.