March may come in like a lion (and go out like a lamb), but April is the peak month to study the constellation Leo the Lion.
Leo is one of the few constellations that actually looks something like the character for which it was named. These stars were recognized as a lion by the ancient Sumerians, Babylonians, Persians, Syrians, Greeks, and Romans (The Chinese, however, saw a horse.) LeoŐs brightest, or alpha, star has long been associated with things mighty and regal. Its name, Regulus, means "little king."
The lionŐs head and mane are formed by a star shape, or asterism, known as the Sickle. (It is sometimes recognized as a backwards question mark or a fishhook.) Regulus marks the heart of the lion (and the dot beneath the question mark). The beastŐs hindquarters are formed by a triangle of stars, including the bright star Denebola, which marks the tail. Leo originally had a longer tail with a tuft of hair at the end, but those stars now make up the nearby constellation Coma Berenices (BereniceŐs Hair).
There are a number of galaxies in the constellation Leo, most lying just beneath the lionŐs belly and not visible without optical aid. On very clear nights some of them are visible through binoculars, and they can otherwise be seen using a telescope. Among the brightest are a very close pair of spiral galaxies called M65 and M66. If you draw a line from the star Regulus to Denebola, these galaxies are about two-thirds of the way to the latter, just below the line.
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 rises about an hour before the sun, appearing above the eastern horizon as the Morning Star. It is in the sky all day, just ahead of the sun as it makes its way across the sky, sinking below the western horizon about an hour before the sun does. 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.
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.