Highlights
In the Solar Neighborhood, the region within several hundred light-years of our solar system that generally shares in the sun’s orbital motion around the galaxy’s center, there are a number of notable open star clusters. The most famous are the Pleiades and Hyades clusters in the constellation Taurus. Another favorite of sky-watchers is the Praesepe Cluster, or Beehive Cluster, in the constellation Cancer.

At a distance of 550 light-years, the Praesepe Cluster looks to the naked eye like a fuzzy cloud. In ancient times some people believed this pale area was a thin spot in the floor of heaven. It was said that through this hole souls descended to Earth to be born. Galileo, centuries later, trained his telescope on it and discovered that it was a swarm of stars.

Once you locate the fuzzy spot that marks the cluster, try the averted-vision technique for a better look. Focus your eyes on the area right next to the cluster, rather than directly on it, and the cluster, which contains about seventy-five visible stars, will become quite visible.

With an age of approximately 800 million years, the Praesepe Cluster will probably dissipate into the Milky Way’s disk within the next ten solar orbits of our galaxy -- that is, within the next two to two and a half billion years. Many of its stars will remain but will have been scattered by the gravitational tugging of the galaxy. This will also be the fate of our other cluster neighbors, the Hyades and the Pleiades. The latter, the youngest of the three, may last a bit longer.

Planets of the Week
Saturn and Jupiter are found in the constellation Taurus, the Bull, and can be seen until late evening. Jupiter is large and bright and one of the first "stars" visible when darkness falls. The two planets are joined by the lovely Hyades and Pleiades star clusters.

Venus disappears from view this week as it passes in front of the sun, but it will reemerge from the sun’s glare as the Morning Star by mid-April. Mars rises just after midnight and is visible until dawn. It lies in the constellation Ophiuchus, the Serpent Bearer, and is just above Scorpius. Mars will brighten, and its red coloration will deepen, over the next few months, reaching its peak in mid-June.

April Constellations
Say good-bye to Orion and the stars of winter, as they appear on April evenings low over the northwestern horizon. Rigel, the brilliant blue-white star marking Orion’s knee, has just set at 10:00 p.m. (daylight saving time). Taurus is very low in the northwest. Capella, the bright star in the constellation Auriga, the Charioteer, is north of Taurus’s orange star Aldebaran.

The Big Dipper, an asterism or star shape within the larger constellation Ursa Major, is very high in the northeastern part of the sky. Its pointer stars, along the edge of the dipper’s bowl, point to Polaris, the North Star, at the end of the handle of the Little Dipper, also known as the constellation Ursa Minor. In the other direction, the pointers point to Leo the Lion in the south. The star Denebola marks Leo’s tail, and Regulus marks his head.

The Big Dipper’s curved handle "arcs to Arcturus," the orange giant star in the constellation Bootes, the Herdsman. Continue the arc past Arcturus to "speed to Spica," the bright alpha star in Virgo, to the southeast. To the right of Spica are the four faint but noticeable stars of Corvus, the Crow. Between Leo and Virgo lies the constellation Cancer, the Crab. Despite being the least conspicuous constellation of the zodiac, Cancer offers a treat to springtime stargazers: the Praesepe, or Beehive, star cluster.

Below and to the left of Arcturus is the semicircular constellation Corona Borealis, the Northern Crown. Farther in the same direction is the butterfly or H-shape of Hercules. Just rising above the northeastern horizon is the sparkling white star Vega in the constellation Lyra. When you see this first of the summer stars, you know that warm weather is on its way.

Sirius, the Dog Star and the brightest star in the sky, is very low above the southwestern horizon now. Procyon, the Little Dog Star, is above it, about halfway up the sky, and Castor and Pollux, the twin stars of Virgo, are higher still. Faint constellations fill in the rest of the southwestern sky.