5 PLANETS TO ALIGN FOR LAST TIME UNTIL 2040.

Byline: Staff and Wire Services

The five brightest planets visible from Earth have lined up in plain sight to form a spectacular celestial array that won't be seen again until 2040.

For the next four weeks, Jupiter, Mars, Mercury, Saturn and Venus will appear tightly clustered in the western sky, forming a knot of planets that can be viewed in the evening, despite the glow of light-soaked cities.

``The five naked-eye planets are converging in one part of the sky and from now until mid-May you can see all five at one glance, which is pretty unusual,'' said John Mosley, an astronomer at the Griffith Observatory in Los Angeles.

Each evening, the alignment will assume different shapes, as the five planets continue on the orbital paths that take them around the sun. The planets orbit in the same plane, like grooves in a phonograph record, only at different distances.

Each planet also varies in the amount of time it takes to orbit the sun: Mercury zips around once every 88 days; Saturn takes more than 29 years; the other three fall in between. At times the planets appear to cluster together.

Similar bunchings occur every 20 years or so, although they are not always visible. The last time they were this visible was in 1940.

In May 2000, the five planets formed a tighter bunch, but were so close to the sun that they were washed out by its glare.

In 2004, they will appear together again in the night sky, but will be spread over a much wider area, said J. Kelly Beatty, executive editor of Sky & Telescope magazine. They won't be as easy to spy at a single glance again until 2040.

``This is the nature of the clockwork of the solar system,'' Beatty said. ``We like to think of it as a way to remind people there is a simple beauty in the heavens that doesn't require any special training to appreciate.''

Astronomers stress there is no astronomical significance to the pileup. It is, Beatty said, just a ``pretty coincidence.''

That hasn't stopped doomsayers in the past. In the months before the May 2000 lineup, some thought it foretold widespread catastrophe, but none happened. In February 1954 B.C., a similar alignment led the Chinese to restart their calendar at year 0, Mosley said.

You don't need a telescope to view the planets, but binoculars can help, particularly in finding Mercury, Mosley said.