On February 4, the planet Jupiter will cross over from the zodiacal constellation of Leo the Lion into Cancer the Crab. My mentor at the Hayden Planetarium, the late Dr. Ken Franklin, used to refer to Cancer as “the empty space” in the sky to his planetarium audiences. Cancer is a star pattern whose brightest star is only fourth magnitude. This makes it difficult, if not impossible to see Cancer in skies suffering from the plague of rampant light pollution.
The night before Jupiter crosses from Leo into Cancer – Tuesday, February 3 – we will have a Full Moon. If you look low toward the east-northeast horizon around 6 p.m. EST, you’ll see the Moon slowly ascending the sky and about 6° to its left will appear Jupiter, the largest of the planets. Jupiter will reach opposition on February 6, meaning it’s opposite to the Sun in our sky. Therefore, Jupiter rises around the time the Sun sets, shines highest about midnight and sets around sunrise. Opposition is also when Jupiter is closest to the Earth for the year, appearing biggest and brightest. Look for it in the east as the blue sky darkens. When you face Jupiter, Venus is almost directly behind you.
How impressive is Jupiter this month? The giant world burns at magnitude -2.6, three times as bright as Sirius, the brightest star, which sparkles very far to Jupiter’s right or lower right on February evenings.
I hesitate to state that Jupiter can be “found” among the stars of Cancer – as if you must locate dim Cancer first in order to find that brilliant planet!