Counting stars by candle light,
all are dim but one is bright:
the spiral light of Venus,
rising first and shining best...
- Robert Hunter,
Terrapin Station
As much as I love looking at extraordinary photographs of celestial objects, nothing can really compare with seeing the universe directly through my own eyes. And, sadly, many people are unaware of the astronomical wonders available to
anyone, using nothing more than a small telescope, a pair of binoculars, or even the naked eye.
One such natural wonder hangs in the Western sky this month -- the beautiful crescent of Venus. Take a walk outside tonight and see it for yourself...and maybe consider how viewing our sister planet helped spark a revolution that can still teach us about the intersection of science, religion, and politics.
After years away from amateur astronomy, I recently rediscovered the hobby that brought me so much joy when I was younger. And, inspired by all of the brilliant science diaries appearing here lately, I want to share how easy and rewarding it is to do some basic stargazing. This will be a series, and I encourage folks to use the comments section to ask questions about observational astronomy, and hopefully report back what you saw (and felt) after spending a few minutes in your backyard looking up at the sky.
I'm starting with Venus because this month offers the opportunity to view the planet at its best. Venus couldn't be easier to find right now. Just go outside right after sunset and look West. Venus is the bright "star" slowly following the sun down to the horizon. If you go out early enough during twilight, it may be the only "star" you see. In fact, Venus is likely the brightest object (other than the sun and moon) you'll ever see in the sky. (Why the "likely" caveat? It's always possible that a very bright comet or supernova might unexpectedly make an appearance at some point during your lifetime.)
Venus is always a beautiful sight and never strays too far from the sun in our sky. This is easy to understand if you think about the fact that it orbits around the sun at a closer distance than the Earth. Imagine a watching distant tether ball swinging around a pole. Always near the sun, from our perspective, Venus sets shortly after the sun or rises a while before sunrise, which is why its also referred to as the Morning Star or Evening Star.
Often if you look at Venus through a small telescope or pair of binoculars you won't see much detail -- just a featureless disc or gibbous. This month, though, Venus is a splendid sight with really any optical aid. Because its orbit takes it nearly between the Earth and the sun right now, Venus appears as a striking crescent. (Cue the wingnuts telling us that this is part of an Islamofascist conspiracy!)
You should be able to see the crescent even in the smallest pair of binoculars. Viewing it last night in my little 60mm refractor (the size of most cheap telescopes), even at low magnification, was stunning. And observing it through my 8-inch reflector wouldn't significantly improve the view. The crescent of Venus is ideal for small telescopes. When I showed it to my 8 year-old nephew last week, he exclaimed: "Look, it's as a smiley-face!"
(Warning: don't run out and buy a cheap telescope! I do encourage everyone to acquire a telescope, but do some research first or ask about it in comments. There are great telescopes available at reasonable prices but the ones you typically find at a sporting goods or department store will end up disappointing you. One of the diaries in this series will cover picking out a good scope. If you want buy an optical aid immediately, I recommend a pair of binoculars for now.)
Here's a challenge -- the crescent of Venus (when it's the largest most pronounced, as it is this month) should be barely visible to the naked eye for those with exceptional vision! I don't really think I can see the crescent shape with my eyes, but go out and try for yourself.
Now, just a bit of history. The crescent of Venus was first viewed through a telescope by Galileo Galilei (or he was the first to record and interpret what he saw, anyway). Based on this and other observations, Galileo quickly realized he had evidence that the Earth and other planets do indeed revolve around the sun, as Copernicus had postulated. This idea, that the Earth does not sit at the center of the universe, did not sit well with the Catholic church. They tortured Galileo and forced him to recant his observations and analysis. He spent the rest of his life under house arrest. Of course Galileo's evidence eventually won out over religious dogma, and the geocentric model of the universe was toppled.
Pondering Galileo's tribulations, I can't help but think of the current "debate" about evolution. Whenever I visit my right-wing, born-again relatives, we enjoy having a lively (and respectable) discussion about evolution. During my recent visit I started the discussion by pointing out Venus in the sky and telling the story of Galileo. At some point, my dad brought up the infamous Charles Darwin "eye quote". Creationists love to claim that Darwin wrote that the human eye could not have evolved, acknowledging that his theory of evolution was wrong. Unsurprisingly, the quote is taken out of context, and when I got home and looked it up I was happy to see that Darwin used the same analogy that I chose to launch the discussion with my relatives.
To suppose that the eye [...] could have been formed by natural selection, seems, I freely confess, absurd in the highest degree. When it was first said that the sun stood still and the world turned round, the common sense of mankind declared the doctrine false; but the old saying of Vox populi, vox Dei, as every philosopher knows, cannot be trusted in science. Reason tells me, that if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist, each grade being useful to its possessor, as is certainly the case; if further, the eye ever varies and the variations be inherited, as is likewise certainly the case and if such variations should be useful to any animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, should not be considered as subversive of the theory.
So go out tonight with a pair of binoculars, a little telescope, or just your own pair of exquisite biological optical instruments (the product of millions of years of evolution) and view the beautiful crescent of Venus. Think about how you're standing on a rock speeding through space, looking at another nearby planet that's majestically reflecting light from our local star. And perhaps contemplate what that little crescent in the sky can tell us about the never ending battle between reason and dogma.
And don't wait! Venus will be lower in the Western sky each night, gone from the evening sky by the end of the month. (Although it will reappear in the morning sky days later.) But you won't see the crescent this large and defined for another eight years!
WARNING: It goes without saying, but never ever ever look at the sun through a telescope or binoculars. Not even for an instant. You'll go blind. No kidding.