The Night’s Shifting Lights
The waning moon rises before midnight Thursday and Friday, with ruddy Mars just a few degrees above. They are high in the south by 4am and in the southwest at dawn.
Monday’s last-quarter moon rises after midnight, just a couple degrees below the bright star Spica. Golden Saturn trails a few degrees to the moon’s east, with the three forming a tight triangle.
Before dawn Wednesday, look for the waning crescent moon at the head of Scorpio, while Thursday it is within four degrees of the scorpion’s fiery heart, Antares.
As the sun sets around 5:00, Venus comes to life. At magnitude –4.0, the evening star is exponentially brighter than any rival. By 6pm, Venus is 20-some degrees above the southwest horizon.
Contrast her prismatic glow to the next-brightest light, Jupiter, high in the south. At magnitude –2.5, Jupiter is roughly one-third as bright as Venus. Each full numeric change in magnitude represents a doubling. So Venus appears twice as bright as a magnitude –3 object and twice again — four times — as bright as a –2- magnitude object. Venus sets around 8pm, which gives you an hour to compare her to the brightest star, Sirius at magnitude –1.4, in the constellation Canis Major, rising in the southeast.
Night by night, Venus outpaces the sun, appearing a little higher in the west at dusk. Jupiter, on the other hand, is edging westward, where the gaseous giant now sets around 1am. By month’s end it will be closer to midnight. And by early March, Venus and Jupiter will be closing the gap, leading up to a fantastic evening conjunction.
First-magnitude Saturn rises in the east around 1am, with the slightly fainter star Spica a half-dozen degrees to the west. They are high above the south horizon before sunrise.