Welcome back, Venus! Brightest planet in the sky returns just in time for the holidays.
"There are so many stars shining in the sky, so many beautiful things winking at you, but when Venus comes out, all the others are waned ...
Mehmet Murat ildan from the play Galileo Galilei (2001)
I miss Venus. The brightest planet in the sky leaves a gaping hole in twilight's tableau when she's gone. Missing in action since late September, it feels like an eternity since we last saw her cheery light at dawn. Or dusk.
That's changing … finally! Venus has been inching into the evening sky ever since superior conjunction on October 25th. What's been taking it so long? The planet's on the opposite side of the Sun from Earth and 155 million miles (249.5 million km) away, near its maximum distance.
The farther away something is, the slower its apparent motion, so Venus tediously claws its way up out of the Sun's fierce glare. The opposite situation occurs at inferior conjunction, when Venus swings between the Sun and Earth and tracks rapidly across the sky.
Have faith. Sightings and photos of Venus's return are already trickling in despite its puny altitude at dusk.
From mid-northern latitudes, the planet hovers just 3-6° high in the southwestern sky 20 minutes after sunset in mid-December. Granted that's low, but from an open skyline and equipped with a pair of binoculars, you can be one of the first to welcome back the Solar System's brightest planet the next clear night.
The situation improves throughout the month. By year's end, Venus will stand 8-10° high and be easily visible without optical aid. My method for finding the planet when it's scraping the bottom of the sky is to note the position of sunset (the brightest spot along the western horizon) and make horizontal sweeps with binoculars to the left and right above that point. Soon enough, Venus pops into view.
From the diagram you can see that as Venus's orbital motion brings it closer to Earth, the planet grows in apparent size and climbs away from the Sun. Its angle to Earth and Sun changes, too, making the planet change phase like the Moon, from full to crescent. This month, Venus is a tiny gibbous lump about 97% illuminated and 10″ across. Through a telescope at 50x, it resembles a minute full moon.
Come spring and early summer, Venus will be out high and bright every evening. Those unfamiliar with the sky will start asking you what that bright thing is in the west after sunset. UFO reports will increase. Venus is like climate change — in the background until it suddenly hits you between the eyes.
In addition to watching the planet ascend to its proper position of radiance, catching one of its many jewel-like pairings with the Moon or a bright planet makes for one of skywatching's greatest pleasures. The coming year offers several must-see events starting on December 22nd when an exceptionally young lunar crescent dangles some 6° north of the planet 20 minutes after sunset.
Between February and August 2015, Venus will pair up with every planet except Saturn. Its conjunction with Jupiter on the evenings of June 30th and July 1st will be the most memorable, when the two luminous heavyweights will be separated by just half a degree.
I think of all the beauty Venus brings to the night sky and am reminded of the wisdom of the ancient Greeks and Romans. They rightly named the bright planet the goddess of beauty and love.
Plan your year with the stars and and planets with the 2015 Sky & Telescope Observing Wall Calendar!