Heads up for five-planet lineup

(CNN) -- Round up the kids and the neighbors any time after dusk during late April and May. The western skies will provide a show that can't be matched by television or the movies. And Mother Nature won't be doing a rerun for decades!

Kelly Beatty, executive editor of Sky & Telescope Magazine, talked with CNN producer Marsha Walton about the unusual planetary alignment that will be visible all over the world for the next four to six weeks.

WALTON: What causes this configuration of planets in our solar system?

BEATTY: The planets operate like a clockwork as they go around the sun, and sometimes they gather together. This is one of those times. Every 20 years or so, Jupiter and Saturn are close together in the sky, and everything else sort of piles up around them. Jupiter and Saturn are in the evening sky. They're very bright, they're very easy to see, and they're being joined by the other "naked eye" planets -- Mercury, Venus, and Mars -- along with the moon this coming week.

WALTON: Do you need any special knowledge or any equipment to take advantage of this spectacle?

BEATTY: This is the most basic kind of astronomy; it's what we call doorstep astronomy. All you really need to do is go someplace where you can see where the sun sets in the west. Keep an eye on that spot as it gets dark. You'll gradually see these planets appear. They'll look like stars but they're not -- they're planets. What's arresting about this view is they all line up in a straight line, starting down very close to the horizon with Mercury and stretching up in a straight line, most of the way overhead to the bright planet Jupiter. On the night of April 17th, they'll all be about equally spaced apart, the moon included.

WALTON: So there's no easy way to tell the stars and planets apart?

EXTRA INFORMATION Celestial stroll

BEATTY: You really can't tell the planets and stars apart. To the ancient Greeks, these were known as wanderers, and the word "planet" derived from the Greek word for "wanderer," so they're "wandering stars." We only know that they're planets because they kind of mingle around the background stars. They move from night to night. And in fact, that's one of the beautiful things about what's going on right now, as you watch these planets from night to night you'll see that their positions change. They're kind of doing a dance with one another as they circle around the sun.

WALTON: When is the next time there will be such a clear lineup of these planets?

BEATTY: The next time we'll have a chance to see anything like this, anything nearly like this will be in the year 2040. That's the next time they'll all be clumped together in the evening sky. A lot of us won't be around then, so I think we should take advantage of this while we can!

WALTON: Where and when should we be looking up?

BEATTY: We're keying on April 17. That's when an eerie straight line alignment takes place. But there will be other nights when there will be interesting things to watch. For example, later in the month, Mercury will be jumping its highest in the sky; you'll be able to see it down low near Venus. On May 5, Venus, Mars and Saturn will form a kind of triangle in the sky.

I'd suggest people make note of where the sun is setting, and then go out another 45 minutes later and look in the same general direction. By then, the sky will be dark enough, the brightest stars will be out, these planets will be out. In this particular alignment, Mars will be the faintest and the hardest to see. Mercury will also be hard to see only because it's down very close to the horizon, so you need a place where it's very clear all the way to the west.

WALTON: Will big city lights make it harder to see this?

BEATTY: Even people who live in the city can enjoy this. Despite all the light pollution that you have to deal with, planets are one of the last things to be blotted out of the sky. So you'll be able to see this no matter where you are -- urban, rural, remote locations -- everyone will get a chance at this one. You should take advantage of it!