April 6, 2000

We have been following the planets Mars, Jupiter, and Saturn since September. This month their nocturnal progress culminates in a splendid conjunction, the likes of which have not been seen since the first year of the 20th century, nor will be seen again until the latter part of the 21st century.

On opposite sides of the sky last fall, the two gas giants are now in the same part of the sky as the red planet, low in the west one hour after sunset. They can all be readily identified tonight due to the placement of a sliver crescent moon, with which they form a lovely quadrilateral.

Saturn is the brightest “star” to the right of the moon, while to their lower right, brilliant Jupiter pairs off with reddish Mars.

Watch for the internal motions among the planets. Saturn and Jupiter continue to close the gap between them, while Mars travels across the gap, reaching midpoint on the 11th and ending the month above the others.

The most compact grouping occurs on the 15th, which, fortuitously, is just before Jupiter and Saturn become too low to be easily seen.

Meanwhile, two stellar animals dominate the evening sky overhead. Just to the south of the zenith lies Leo the Lion, his head to the right, forming a backward question mark. Just to the north of the zenith lies Ursa Major, the Big Bear, best known for the prominent asterism she contains, the Big Dipper.