I went hunting for a goddess the other night. For the past few months this deity has been elusive…appearing only in the early morning hours, and only in the east. Now, however, the goddess of love—a.k.a. Venus—has swung to the other side of the sun, from earth’s perspective, and, thus, should start being visible in the evening.
A month from now Venus will be easily seen because it will be far enough away from the sun to be visible well after sundown once the sky is very dark. But Venus just emerged from behind the sun in early April, so I wasn’t at all sure I could catch an early glimpse. It would require very clear skies and a western view almost to the horizon. Since the view west from my house is obscured by trees, I decided to climb to the Summit House on Mt. Holyoke to try my luck.
As befits its mythology, Venus truly is a beautiful sight. It is the brightest object in the sky, after the sun and the moon, and is much brighter than Sirius, the brightest star in the northern hemisphere. The brilliance with which Venus shines is due to both its relative nearness to Earth and the amount of light it reflects. Reflected light is measured in terms of albedo, which ranges from 0 for something so black it absorbs all light, to 1, for something so blindingly white that it reflects all light. The Earth, which has both high-albedo features (e.g., ice caps) and low-albedo features (e.g., forested terrain) has an albedo of 0.3. Mercury, which is basically a pock-marked rock without an appreciable atmosphere, has an albedo of only 0.12. Venus, in contrast, has an albedo of 0.75, which is the highest of any planet.
That high reflectivity is due to the thick blanket of clouds that permanently shroud the planet. As pretty as Venus is from earth, its surface is a hellish, rocky wasteland, baking at 880 degrees F with a smothering atmospheric pressure equivalent to being about a mile under Earth’s ocean. Were you unlucky enough to find yourself standing unprotected on Venus, not only would you be instantly roasted and crushed, your remains would be quickly dissolved by the high levels of sulfuric acid lacing the atmosphere.
I’m quite happy, therefore, to admire Venus from afar. I brought along my binoculars, hoping to see both Venus and Mercury, which lie very close together at the moment from our perspective. Mercury doesn’t look like much…a faint pinpoint of light, even in binoculars. But I enjoy spotting it anyway when I can.
My binoculars are not powerful enough to allow me to see Venus’s shape. Venus has phases, somewhat like the moon, except that we can never see a “full Venus” the way we see a full moon. That’s because when Venus and the Earth face each other directly, they are across the solar system from each other and the sun is smack in the way. As Venus emerges from the sun’s glare, as it is doing now, it is a little less than full. It will get thinner and thinner in the months to come until we see a “half Venus” (in a telescope) and then it thins more until it again becomes invisible, soon to return to the morning skies. (This is one of those times when a picture really is worth a thousand words. Check out this illustration of the phases of Venus.)
I followed the summit road to the “halfway area,” then climbed the steep trail up the west side of Mt. Holyoke to the Summit House. I didn’t need a headlamp. The moon was up and bright enough to cast shadows and light my way.
Our eyes have a tremendous range of light sensitivity if you give them a chance. Once our eyes fully “dark adapt,” they are from 10,000 to a million times more sensitive to photons than they are in full daylight. It typically takes between 20 and 30 minutes for this adaptation to occur. Not only do our pupils widen fully in this time, the rod cell photoreceptors in the retina become fully sensitized. Rod cells can detect single photons of light and are 100 times more sensitive than the three types of retinal cone cells that provide us with color vision.
People are often surprised by how well they can see at night after they switch off their flashlights and let their eyes adjust. I’ve taken entire hikes without a headlight, even in summer, although if you are in the woods on a moonless or cloudy night in summer it can get very dark indeed, so I always take a light, just in case.
If you haven’t tried night hiking or walking, I encourage you to try. A trail you’ve been on a dozen times in daylight will feel delightfully new at night. I’ve never heard coyotes howl during the day, for example, nor owls hoot. And sometimes you hear things at night that are truly weird…mating porcupines and screech owls, for example, which make fairly blood-curdling, screaming sounds that words can’t do justice to, but which are amazing to hear.
No bizarre sounds echoed through the woods as at I walked, however. An icy wind blew from the northwest and the woods were as silent as January.
At the top the wind was even more biting. The view straight up was clear, the stars glittering. But a bank of low clouds to the west obscured exactly the area where Venus and Mercury were supposed to be. I waited a bit, sheltering in the lee of the old hotel, hoping for a clearing. I admired Orion and the glowing ember of Mars, but the clouds only got thicker, so I gave up and enjoyed the walk back down.
The next day I tried again, encouraged by the forecast of clear skies. This time I aimed for Mt. Pollux, in South Amherst, which is possibly the most diminutive lump of topography ever granted the appellation “mountain.” Modest as it is, however, it has a great view west.
As the sun sank, a group of young women chatted beneath the lovely sugar maple at the top of the hill. The western sky was banded with layers of peach, apricot, and pale lemon fading into the deep velvet of the night sky. It was hazy, but not cloudy. Still, I could see nothing with my naked eyes or binoculars. I sighed and took a walk. The wind was still brisk but it was warmer and I heard a number of birds calling, including some Canada geese quarreling somewhere toward Mt. Norrotuck.
Ten minutes later I returned to the top of the hill and tried again with the binoculars. This time Venus was instantly visible, a bright dot light flashing rainbow colors as the light passed through miles of turbulent, refracting air. I saw no sign of Mercury–it was just too faint and too close to the sun to see. Perhaps if I had stayed another 15 minutes I might have glimpsed it. But I was satisfied to welcome the goddess of love back to familiar evening hours. I’m looking forward to watching her dazzle ever brighter as our two planets draw closer in their orbits. Venus will be at maximum brilliance late in December, which will be a lovely beacon in the long nights near the solstice.
Almanac is a regular Indy column of observations, musings, and occasional harangues related to the woods, waters, mountains, and skies of the Pioneer Valley. Stephen Braun has a background in natural resources conservation, which mostly means he is continually baffled by what he sees on explorations of local natural areas. Please feel free to comment on posts and add your own experiences or observations. You can also email at: firstname.lastname@example.org.