Wednesday, February 28, 2007

Astarte’s Crescent

3/4/07 – 3/10/07
by C. Zaitz

The crescent may very well be one of the most beautiful shapes of our lovely neighbor, the moon. The curved smile of the young moon after it has just passed through its shadowy new phase is a crowning jewel to twilight’s glorious robes of color, but sometimes that shadowy grin looks like a smirk, and sometimes a friendly smile.

Sometimes when you look at the crescent moon, it appears to look like the letter “C”, only backwards, more like a “D” without the straight part. But sometimes it looks like the letter “U,” or a birch bark canoe sailing over the horizon before it dips below the earth. I saw the moon looking like that last month, and I wondered about it.

It was an unusual sight. I wasn’t used to seeing the crescent moon in that position, and strangely I had just read an article about how the crescent moon looks like a “U” from latitudes near the equator. So why was our crescent moon looking like that, at our latitude, nearly halfway to the North Pole?

It’s true that near the equator, the crescent waxing moon looks more like a boat than a banana. It sets nearly straight down, chasing the sun to the ground. The sun does the same thing; near the equator the sun rises nearly straight up and sets the same way. In Michigan, we only see that on the vernal or autumnal equinoxes, when the sun crosses the celestial equator (an imaginary projection of earth’s equator onto the sky.) We remember that earth is tipped 23.5 degrees with respect to the plane of our orbit around the sun. If we project the plane of our orbit out into space and also the equator, these two circles cross at two points. One is in the spring, and the other is in autumn. We call these two days the equinoxes, and we are coming up on the Vernal or spring equinox. It’s at this time of year that the sun rises due east and sets due west. The moon’s orbit is only tipped about 5 degrees from the plane of our orbit, so it’s following that path pretty closely. So if the sun seems to rise and set straight up at this time of the year, it stands to reason that the young moon would as well. Thus we see our smiling moon.

In ancient times the crescent moon was the symbol of the Phoenicians goddess Astarte, known as Ishtar to the Mesopotamians, Diana to the Greeks and Venus to the Romans. Her “bediamonded crescent” was poetically captured by Edgar Allan Poe. You can see the crescent moon in modern times on flags and images from many different cultures. Muslim holidays and religious observances often start or end with the first sighting of the waxing crescent moon. The optimal conditions for sighting the young moon is when the angle that the moon sets is nearly perpendicular to the horizon, which happens to be around mid March for the Northern Hemisphere. The next young crescent moon will appear a few days after new moon, so look around the 19th or 20th of March to see if you can spot it. If you don’t see it one night, look the next. You’ll see the slim crescent grow, night after night, and be a witness to one of the more beautiful sights in the sky.

Until next week, my friends, enjoy the view.

Tuesday, February 20, 2007

Waltzing with Luna

2/25/07 – 3/3/07
C. Zaitz

Did you ever notice that when you gaze at the full moon, it always looks the same? It’s not just a round bland face; it has features. Some say it has a smile, or that the dark areas look like a bunny or frog or even an astronaut tickling the chin of a poodle. Next full moon, take a look and notice what you see. It’s what you’ve seen your entire life.

Maybe you don't miss the other side of the moon, but isn’t it odd that we never get to see it? It’s a sphere, so it must have other faces, but we only see the same one, over and over. In fact, no one had ever seen the back side of the moon until 1959, when we sent rockets around our cosmic companion. It turns out that the other side of the moon is very different from the side we see. There are no dark areas to make smiles or bunnies. It’s all “highlands,” with very few “maria,” the dark lava “seas” that make the shapes so familiar to us on our side of the moon.

Notice I didn’t say “dark side of the moon.” No offense to Pink Floyd, but technically it’s not correct to refer to the other side of the moon as the “dark side,” since over the course of a month it gets just as much sunlight as the side facing us.

So the question is: why do we see only one face of the moon? Is it because the moon isn’t rotating? Actually, with respect to the stars, it is rotating. If it didn’t rotate, over the course of the month we’d see all of it. It would slowly show each nook and crater to us. Instead, it rotates at the same speed that it circles us. This is called synchronous rotation, and it turns out that it is no accident. The majority of the moons in our solar system are synchronized with their parent planet. It’s all about tides.

We may remember that the moon tugs on the earth and creates tidal bulges in the oceans, but what we may not know is that even rocks and dirt feel the effects of that tug and experience tidal bulging. Tidal bulges occur in any body that is tugged on by other bodies. The result of these bulges is that they act like little friction brakes to the spin of the object. The moon is causing the earth to slow down. As a thank you, the earth is sending the moon farther away from us to conserve angular momentum. Meanwhile, the two are facing off like a bullfighter and his bull. The moon has already succumbed, but eventually, earth will slow enough so that one face will point eternally toward the moon as well. Then they will dance, staring each other down, until the sun itself burns out and goes dark.

This effect is called tidal locking, and is the opposite of rare in the solar system. Given enough time, most objects will have orbital and rotational resonance with their nearest gravitational partners. If that sounds like heavy duty physics, it is. But it’s also beautiful, because the whole system of planets, moons and the sun will be in sync, in a cosmic waltz, pirouetting at the same time, locked in eternal embraces. I wonder what the band will be playing for the dance. Perhaps it will be the music of the spheres.

Until next week, my friends, enjoy the view.

Tuesday, February 13, 2007

Star-crossed Science

2/18/07 – 2/24/07
by C. Zaitz

I recently had a conversation with high school students about astrology. Astronomy and astrology have been around for thousands of years, but the science of astronomy only broke with the art of astrology a few hundred years ago. Astronomia was the old word for the scholars who undertook the duties of observing and predicting sky motions, interpreting them and applying them to earthly events. In fact, the observatories and salaries needed for observing and predicting (astronomy) were often paid for by the profits made by interpreting and applying (astrology).

Most of the great astronomers we can think of were also astrologers. There was no shame in casting horoscopes. In fact, it was quite a lucrative business for some. Johannes Kepler, known to scientists for his three Laws of Planetary Motion, was a prolific astrologer while he wasn’t trying to figure out the nature of things. When his paycheck didn’t arrive from his day job as a mathematician and astronomer, as it often didn’t, he resorted to casting natal charts and predicting events to feed his family. Kepler sometimes balked at mundane astrological duties, thinking that most common folk were too superstitious and ignorant to understand the true beauty of astrology. To him it was art married to science, it was real, and it meant something. It was a taste of the divine. Galileo, a contemporary of Kepler and famous for first gazing at the heavens through the newly developed telescope, also shared Kepler’s use of astrology. In fact, though some use Galileo as an example of one of the first scientists divorced from superstition, it’s much more likely that Galileo, like his contemporaries, viewed astrology as an aspect of religion and world view, where what happens above happens below, and that the heavens are reflected on earth. He cast horoscopes and charts like his contemporaries, when he wasn’t spying on the rings of Saturn or the moons of Jupiter.

The idea that earth is a reflection of the machinations of heaven is a beautiful thought, so it’s no wonder the notion has been around so long. But it began to lose favor in the mid 18th century. Why did astrology and astronomy split up? Perhaps because science and scientific methods became so important by making life better and for improving technology that people no longer wanted to rely on an “unscientific” form of prediction. Astrology became known as an occult or superstitious science, and the Age of Reason did not leave room for superstition. However, it didn’t go away completely, it just moved to the realm of divination.

Does that leave astrology without a foot hold in modern society? Many of us read our horoscopes in the newspaper for amusement, and some of us take it a bit more seriously. When I questioned the students about astrology, the vocal ones indicated that they thought it was somewhat silly. But the silent ones may have had different feelings that they were embarrassed to express in a science class. Nowadays it’s considered almost ignorant to believe in astrology. Yet, I don’t think humans will ever stop trying to make connections between what happens “below” and what might be happening “above.” And what better way than to watch the beautiful stars and planets? I almost admire people who find connections between the planets and their lives. I have never been able to, but wouldn’t it be fun to think that everything could be explained by looking at the stars?

Until next week, my friends, enjoy the view.

Monday, February 05, 2007

All This Useless Beauty

2/11/07 – 2/17/07

by C. Zaitz

Sometimes the sky overwhelms me. It is just so beautiful. When I run outside to let the dog out, the sky just catches me until I don’t know if it is the cold making my eyes tear up or if I’m really crying at the beauty.

That beauty is what caught me at a young age to want to know more about the Universe. I think the sky is rather like art. Sometimes you can look at a work of art and its beauty affects you, even if you don’t know anything about the artist or subject. However, when you look a little deeper, things really start to open up. Perhaps the first time you saw “Starry Night” by Vincent Van Gogh you thought, “well, that really doesn’t look like the sky at all!” But then you learn that he wasn’t really painting the sky so much as he was using images as a vehicle for his emotions and whirling thoughts. You begin to see the painting as an expression of impressions, and then you can understand the beauty of it on a different level.

For me, the beauty of the sky has inspired me to learn more. I think a pretty sunset over a gorgeous landscape can be just that, a pretty view. It can also be more. If you look into it, you can get a further appreciation of the magic of a sunset. You can learn how erupting volcanoes can make some of the most beautiful sunsets ever. But they can also extinguish life on earth.

When I was young and saw the moon through a telescope, things changed for me. The moon is positively scarred with craters from collisions with meteors and asteroids. I learned that the earth has been pummeled as well, even more than the Moon since it is larger. I no longer believed that the earth was a charmed planet, and that no asteroid would dare collide with MY planet! I guess I got a dose of reality.

It’s nice to look at the beauty of the earth, to watch the shows on the Nature Channel or even go hiking or boating to enjoy nature. But there has been a lot of talk lately about how we have changed our environment simply by thriving in it, by harnessing the energy of the earth in order to make our lives more secure and comfortable. Though there is debate about the extent of global warming and its timeline, there is a great amount of evidence telling us that we are affecting our environment in a way that is detrimental to our continuation as a species. It’s beautiful and awesome to watch huge chunks of Antarctic ice falling into the ocean. There’s a certain amount of inevitableness about it. I suppose that’s why we don’t lie awake worrying about asteroids hitting us. Yet we aren’t dinosaurs. We are capable of good and great things. But if all the beauty that inspires us doesn’t urge us to look deeper into what we’re doing, it might all go away. Or maybe we will. All this useless beauty, if we don’t read into it, if we don’t look a little deeper than the surface of the sunset, or the story of the moon. Useless beauty if we don’t take the time to understand ourselves and our environment. And it’s such a fascinating story!

Until next week, my friends, enjoy the view.