Three bright planets congregate in the southeastern quadrant of the sky at dawn this month. Jupiter is the brightest and highest of the three, shining brilliantly from near the center of Libra, high in the south at first light. At the same time, Saturn is low in the southeast, just above the teapot formed by the brightest stars of Sagittarius. Mars slides between them. It begins the month closer to Jupiter (and close to its “rival,” Antares), but ends the month closer to Saturn.
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In the Sky This Month
February 17: Mercury in Conjunction
Mercury, the smallest of the solar system’s major planets, is hiding in the Sun’s glare. It lines up behind the Sun as seen from Earth. As it moves away from the Sun, it will climb into decent view in the early evening sky in a couple of weeks.
February 18: Columba
Columba, the dove, scoots low across the south tonight, to the lower right of Sirius, the brightest star in the night sky. The constellation marks the opposite direction from the motion of the solar system as it orbits the center of the galaxy.
February 19: Doomed Moons
Three constellations in view this month are named for early machines: Sextans, Antlia, and Pyxis — the sextant, air pump, and magnetic compass. Sextans is low in the east in early evening, with Antlia and Pyxis climbing into the south and southeast.
February 20: Canis Major
The constellation Canis Major, the big dog, is best known for its leading light: Sirius, the Dog Star, the brightest star in the night sky. It stands a third of the way up the southeastern sky at nightfall.
February 21: Wezen
Canis Major, the big dog, is in the southeast as night falls. The constellation’s third-brightest star, Wezen, is one of the biggest, brightest stars in our part of the galaxy. It’s also one of the youngest, at an age of just 10 million years.
February 22: First-Quarter Moon
The Moon will reach its first-quarter phase tonight, as sunlight illuminates half of the lunar hemisphere that faces Earth. The illuminated fraction will grow larger each day until the Moon is full on March 1.
February 23: Moon and Aldebaran
The bright orange star Aldebaran, which marks the eye of Taurus, the bull, stands to the lower right of the Moon as night falls and leads the Moon down the western sky later on. The star is about 65 light-years from Earth.