Phosphoros Lights up Twilight
The brightest Evening Star
Sunset finds Venus ablaze low in the southwest before setting by 8pm. There is no brighter planet or star, and so close to the horizon Venus can pulse and shimmer as its light is distorted by our atmosphere. Traveling close to the sun, Venus appears for at most a few hours either after sunset or before dawn. This led early civilizations to believe that the evening star and the morning star were two distinct objects. The ancient Greeks called the morning Venus Phosphoros and the evening apparition Hesperos. It wasn’t until the age of Greek enlightenment in the fourth century BC that both objects were recognized as the same.
Another planet doesn’t appear until nearly midnight when Jupiter crests the east-northeast horizon. Thursday evening the moon precedes it by less than 10 degrees, while Friday the two have swapped places. By daybreak they’re high in the south.
To the north of Jupiter are the twin stars of Gemini, Castor and Pollux, while to the south of the moon is Procyon of Canis Minor. Procyon is the seventh brightest star at magnitude .34 but is still no rival to Jupiter, which shines at magnitude –2. Saturday Procyon, Jupiter and the last-quarter moon form a tight triangle.
Tuesday the waning crescent moon rises around 2am with Mars trailing less than 10 degrees. Blue-white Regulus is equally close to the two, forming a near-perfect triangle. The next morning the moon is farthest east, but the three still form an obtuse triangle.
Around 10pm the constellation Pegasus shines directly overhead. While its brightest stars are only second magnitude, each marks a corner of a great square. The brightest star, Alpharatz, marks a string of stars stretching to the northeast that ends in a smudge of light. It is actually the combined light of hundreds of billions of stars making up the Andromeda Galaxy 2.5 million light years away.