If you haven’t yet checked out Venus glistening low in the southwestern sky at dusk, now would be a great time to do so. Many people might have missed seeing it there because of low-lying clouds or mountains blocking the view, but with late December upon us, it’s now beginning to climb higher in our sky as it rounds the sun.
As more and more people spot its brilliant light in the early evening sky, more and more misconceptions about just what it is will begin to pop up. I certainly hope that regular readers of these columns won’t fall prey to these, but you may encounter some in your interactions with other less experienced stargazers.
Perhaps the most common misconception of novice sky watchers is that the brilliant light of Venus is an approaching aircraft with its landing light on. I suppose this is an easy mistake to make; even a World War II fighter pilot reportedly was fooled and actually fired on the planet.
He missed.
Another common belief is that it’s the International Space Station. Of course, the space station orbits the Earth about every 90 minutes, so it appears to drift gracefully across our sky from time to time. Venus doesn’t. (Click here to predict the actual passage of the International Space Station across your sky.)
Perhaps most puzzling to me is the idea that it’s the North Star. I guess folks aren’t bothered that it appears in the southwest!
Whenever you encounter misconceptions such as these — and I’m sure you will — be patient, and take time to explain what people are actually seeing. Helping others enjoy the wonders of the night sky is a tremendously rewarding way of spending your time.
Ever since my youth, I’ve enjoyed the company of Venus in the glow of twilight, especially when it’s nuzzled against the delicate crescent moon. Fortunately, this sight is not all that uncommon, occurring once a month or so as the moon orbits our planet. And just such a pairing is coming up this week.
After sunset on Saturday, Dec. 28, the delicate crescent moon will appear right next to brilliant Venus and create a magnificent sight in the waning light of dusk.
As you admire the pair, be sure to check it out with binoculars, since few celestial sights appear more three-dimensional. You’ll surely enjoy seeing the faint disk of the full moon, the result of sunlight reflected off the Earth back onto the dark side of the moon.
The appearance of this ghostly glow was first explained by the famous 15th century Italian artist and inventor, Leonardo da Vinci.
He recognized that when the moon appears as a crescent in our sky, a hypothetical lunar astronomer would see in his sky a nearly full Earth. And, just as a bright moon illuminates the dark night on Earth, a bright Earth would illuminate even more of the darkness of the moon. Today we call this phenomenon “Earthshine.”
I hope you’ll mark your calendars for Saturday’s beautiful sky show; I know I’ll be out keeping watch at dusk, reliving fond memories that extend far back to my childhood!
— Dennis Mammana is an astronomy writer, author, lecturer and photographer working from under the clear dark skies of the Anza-Borrego Desert in the San Diego County backcountry. Contact him at mammana@skyscapes.com and follow him on Twitter: @dennismammana. The opinions expressed are his own.