Last weekend, Mars passed nearest to Saturn in our sky. But this week, before Mars and Saturn can get very far apart, a planet more than 100 times brighter will move in to form a tight triangle with them. This, at last, is the week of the Venus-Mars-Saturn trio - a sight that should be one of the best of the year in astronomy.

Triangle of planetary lights: Five degrees is half the width of your fist at arm's length. It also is the width of the field in many binoculars. If three heavenly objects move to temporarily fit within a circle less than 5 degrees wide, the formation is officially callled a trio.

Mars and Saturn will be hard to see until evening twilight fades and then will be so near to setting that the extra haze down low on a humid day will greatly dim them. You may need binoculars on a few of these nights to see Mars and Saturn.

How to view the trio: Make certain that your view is unblocked down to within 10 degrees (one fist-width at arm's length) of the true horizon. By a little after 9 p.m. - about 45 minutes after sunset in New Jersey - the trio will be only about 10 degrees above the horizon, a bit left of due west.

Incidentally, if you want to spot a fourth planet - Mercury - you should start looking no later than 9 p.m. and be able to have a clear view virtually right down to the due west horizon, which Mercury's speck of light will be near then.

Between 9 and 9:30 p.m., the sky will darken and the trio will brighten, but after that the effect of the three planets sinking lower in the haze will begin to dim them again. Venus, Mars and Saturn will set about 10 p.m.

Each night's lovely triad: Yellow-white Venus will be easily visible each night this week. The next few evenings, deep-gold Saturn and slightly dimmer, slightly more orange Mars will appear to the upper left of Venus. Then, on Friday, Saturn will be directly above Venus. Next, Venus will start moving to follow the fleeing Mars, leaving Saturn to the upper right of Venus.

The three planets will meet the definition of a trio Friday through Sunday nights. On Saturday and Sunday, Venus also will be closest to Saturn - less than 3 degrees (a bit more than the width of your thumb at arm's length) from it.

If you have a telescope, be sure to view close up each of the three very different-looking planets.

Get ready for next week's meteor shower: The planets next week, joined by the moon, will continue to put on a fine show. But the big show will be the strong Perseid meteor shower, which will peak in the hours before dawn Friday, Aug. 13.

Fred Schaaf is a local author and astronomer. He can be reached at: