Full moon takes toll on winter star gazing
The monthly celestial whiteout kicks in this week and serious stargazing is shut down once again.
The moon will be exactly full on Tuesday night, but for most of the week, it will be close enough to being fully lit that it will wash out all but the brightest stars and constellations.
Full moons are especially obtrusive to amateur astronomy this time of year because our lunar friend takes such a high trek across the sky through the night. It takes more or less the same high path across the heavens as our sun does during the summertime. That's because the full moon and the sun are in opposite directions from our Earth in space, thus putting them in opposition in our sky. That's why the full moon rises at sunset and sets at sunrise.
What further complicates this matter is the fact that the Earth's axis is tilted 23Z\x degrees to its orbit around the sun. In the summer, when the northern hemisphere is tilted more toward the sun, the sun takes a high arc across the sky and the full moon takes a low track. In the winter, when our northern hemisphere is tilted away from the sun, the sun makes a low east to west sojourn in our sky and the full moon rides high.
Now I don't want to come off like one of those second-rate sports columnists that love to rip, rip, rip everything and anything. There's a lot about the full moon I truly love. Like anyone I try to see the face of the man in the moon, but being a child growing up in the 1960s and early '70s, I also find myself thinking about the men who walked on the moon. I wish a woman had a chance to stroll on the lunar surface. In the future, I'm sure it will happen, but unfortunately back then it was mainly a man's world when it came to spaceflight.
A total of 12 men walked on the moon, and everyone knows that the first man to step on the surface in July 1969 was Neil Armstrong, commander of Apollo 11. December was the 35th anniversary of Apollo 17, the last manned mission to the moon. Do you know the name of the last man to walk on the moon? Unfortunately not many do.
The early missions to the moon mainly landed on the "lunar maria," dark areas of the moon that are named as seas and oceans because a long time ago, before there were telescopes, people thought these dark splotches were actually huge bodies of water.
In fact, Apollo 11 made the first lunar landing on the Sea of Tranquility. Actually, these seas and oceans are relatively flat lunar plains made by volcanic flows. They are thought to have occurred between 3 and 4 billion years ago. They were desirable landing sites for the first lunar missions because of their generally flat, smooth surfaces with not all that many craters.
The whiter sections of the moon's face are the more hazardous cratered highlands. Most of the impact craters on the moon were created during the chaotic early years of our solar system more than 4 billion years ago. The entire lunar surface was probably heavily cratered back then, but the volcanic flows and hardening about a billion years later resurfaced parts of the moon.
For sure there are some craters on the maria, but not as many, because by the time the maria formed, most of the heavy meteor bombardment had subsided.
As much as the moon can be annoying to stargazers, it's a good thing the moon is around. For one thing, it slowed down the Earth's rotation because of its gravity and tidal forces. Back when the Earth was young, more than 4 billion years ago, it took only eight hours to make one spin on its axis. That made for a really fast day! Because of the moon's gravitational tug, the Earth has slowed to a 24-hour rotation.
The moon's gravity also keeps the Earth's axis in control. Without the moon, many astronomers believe that our axis would go through all kinds of wild gyrations because of the gravitational tugs from Jupiter and the other planets. That would make our world a lot more hazardous for life as we know it.
Even with all the good it does for our world, if you still don't like the moon, just wait awhile. The moon is actually moving away from the Earth. Every year it moves an inch and a half farther away. In 3 billion years it will be over 70,000 miles farther away!
Meanwhile our up-close-and-personal moon and the bright planet Mars will be practically touching each other in the heavens. They'll only be about one degree apart and will make for really good eye candy.
By the way, the last man to walk on the moon was Gene Cernan in December 1972. Who will be the next person to walk on the moon? Stay tuned!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, "Pennsylvania Starwatch," available at bookstores and at his Web site www.lynchandthestars.com.
