Astronomy has always held a profound fascination for me, for one because scientists are always making new discoveries, and therefore so are the rest of us. But some things I never learned before, such as the phases of the planet Venus, when it appears as a crescent, like the moon. Visible through even a low-quality telescope such as ours, the planet teased me for a moment into thinking I could see it with the naked eye. But who knows what exists in that uneasy grey area between things seen and unseen?
In clear weather, this is the first planet even visible before sunset in the southwest sky. Venus climbs in the twilight, after months of obscurity near the horizon. The planet brightens, hurtling toward Earth, rotating more closely around the sun. It whirls inside Earth’s orbit, switching from evening to morning sky and back in about nine months at a time. When Venus is opposite the sun from Earth, it appears full and small because of its great distance. But as it moves faster than the Earth around the sun, it gets closer and looms larger and larger. Also altered is the angle of sunlight striking it: as Venus passes between Earth and sun it appears as a waning crescent.
Venus’s greatest brilliance occurred on December 6, between when it looked full but minuscule, then much larger as a slender crescent. This was due to the great illuminated surface area and increased size. Venus appears so bright, in a clear afternoon sky on its approach toward Earth it can be seen with the naked eye! Viewed through a telescope, with the passing nights its crescent grows larger and slimmer, even glimpsed through binoculars, at 37 million miles from Earth. Then, Venus’s crescent will continue to narrow, but because it’s still approaching us, will also lengthen as it pitches precipitously toward the sun. Finally, on January 11, Venus will seem to pass between the Earth and the sun, emerging as a new morning “star,” easily spotted in the hour before sunrise as it rises in the east-southeast dawn.