We live in a fairly dark site, about 10 miles from the nearest town, on a nice rise with a clear south view, surrounded by large working farms. The roads are gravel. When the moon is toward new and offers no friendly moonlight to help me find my way on a pre-dawn walk, I have to navigate by touch. It is literally pitch black out there. I wear my old, thin-soled boat shoes, and try to walk the smooth track, right or left, between the graveled crown and shoulder of the road, slowly making my way under a dense canopy of trees. When I get to the open fields it’s easy to find my way by starlight, or the faint bloom of Charlottesville. I follow the vague off-white blur of Hambone, our hound, too. Always up for a walk, even at 4 in the morning.
Venus has been the ‘Morning Star’ since early April. This is the object I’ve seen each clear morning, low in the east, when I round the bend on Foster’s Branch Road, and come out from under the Oaks and Poplars. Venus has risen steadily earlier since April (and was therefore higher in the sky at, say, 4:30 or 5 AM) and continued thus through about mid July, when in moved into Taurus from Aries. Since mid July it has steadily drifted back toward the east horizon, rising closer to dawn (later) each day, moving through Gemini, Cancer and Leo. Come December, it will disappear into the glare of the sun, in Virgo, and then appear again, late March / early next April, 2010 this time as the ‘Evening Star,’ at nightfall… again in Pisces, about where is was last April.
Venus and Mercury are ‘inner’ planets – they orbit the sun inside our orbit; their orbits are smaller than our orbit. Mars, Jupiter and Saturn are more distant from the sun; their orbits are larger than ours. The outer planets. From our perspective on the home planet that lets us see Mercury and Venus, the inner planets, on either side of the sun, depending on where they are in their orbits, in the morning or evening twilight — visible in the sky before sunrise, or after sunset.
So, Venus is both the ‘Morning Star’ and the ‘Evening Star.’ Technically the term refers to any exceptionally bright object, star or planet, that shows prominently in the morning or evening twilight. But in common usage the term almost always refers to Venus. Each apparition of Venus (the astronomy term that refers to its cycle of visibility) as the ‘Morning’ or ‘Evening’ Star lasts about six to seven months. When it passes behind the sun, its lost from view for several months, transitioning from ‘Morning’ to ‘Evening’ star. When it passes in front of the sun, it’s lost from view for several weeks, transitioning from ‘Evening’ back to ‘Morning’ star. This is for the casual, naked eye observer. If you’re looking hard, with binoculars or a telescope, the apparition will be somewhat longer. In fact, earlier this year, a keen observer could see Venus both in the morning and evening twilight, on the same day, because the offset of its orbit took it unusually far north of the sun. That doesn’t happen too often.
By the way, the upper graphic – the ‘overhead racetrack’ was based on the graphic done by Fred Schaaf in Sky&Telescope magazine. (OK, so I pretty much just re-drew exactly what he had done… but at least I re-drew it!) He does a monthly summary article (among other articles) on positional astronomy for S&T. This is my favorite sources of information, and Mr Schaaf’s arcticles, in particular, are the first I read. Thanks Fred!