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.