Wednesday, January 30, 2008

Moon Dragon

2/3/08 – 2/9/08
by C. Zaitz

Michigan winters can drag on and on, but soon there will be a real “dragon” in the sky; the moon-eating dragon we know as a lunar eclipse. The word eclipse is Greek, meaning “abandoning” or “forsaking.” On February 20th, around 9pm, you will see our lovely full moon abandon us as it is “eaten” by the shadow of the earth.

Lunar eclipses may seem rare, but they actually happen twice a year. We cannot see them if they happen during the day. The moon is always full during a lunar eclipse, and full moons are always opposite the sun. As the sun sets, a full moon rises, and as the sun rises, the full moon sets. That is why we see a lovely, huge, and sometimes reddish full moon rising at sunset. The color comes from light getting scattered as it passes through the atmosphere, but the apparent size is an optical illusion, due to the moon being close to the horizon.

A lunar eclipse happens when the moon passes through the earth’s shadow. As the moon orbits the earth once a month, there will be a time when the sun, earth and moon are in a line. The moon’s orbit around us is tipped about 5° from our orbit around the sun, so usually it passes above or below our shadow cast into space. Twice a year, the orbits cross so there is a chance for a lunar eclipse, but sometimes the moon may skim only part of the shadow. There will be such an eclipse in August, but it happens during our daytime so we will not be able to see it. The February eclipse is total and happens at night. This is our eclipse.

So here are the nitty-gritty’s of this eclipse. It begins with the moon moving into a penumbral shadow at 8:43 pm on February 20th. This will be hard to see, since penumbral shadows are light. The full eclipse begins at 10:01pm, and by 10:26 the entire moon will be eclipsed. This is when you can tell what color the eclipse is. Will it be reddish, like a rising full moon sometimes is, or will it be dark grey or brown? Sunlight passing through the atmosphere is responsible for the colors of an eclipse. Even though the moon is in our shadow, some sunlight does pass through our atmosphere and falls on the moon. Depending on how much the light is scattered, the colors can range to orangey red to dark, muddy brown. The more stuff in the atmosphere, (ex. volcanic ash) the darker the eclipse.

Eclipses were often seen as bad omens, especially solar eclipses, as if the sun and moon were being eaten or destroyed by dragons. People had different methods of scaring away the moon-eating dragon, such has making loud noises or praying. The best remedy for an eclipse, though, is time. By 10:51pm the total eclipse will be over, and the moon will be completely out of the earth’s shadow by 12:09am.Hopefully the skies will be clear so we can all enjoy this special event.

Until next week, my friends, enjoy the view.

Tuesday, January 22, 2008

Messenger from Space

A space craft called Messenger was launched back in August of 2004, en route to the smallest of the planets, Mercury. Tiny and dense, closest to the sun, and with a very ancient surface, Mercury should be a planet of great interest, but has been largely ignored for most of the era of solar system exploration.

Only one other spacecraft has visited Mercury. From 1974-1975, Mariner 10 flew by and sent back the pictures of the heavily cratered planet. The data showed a hot little world, burning and freezing alternately through its day and night. The surprising thing learned by Mariner about the closest planet to the sun is that there are spots that are colder and darker than many places in the solar system. One of the reasons we’re so curious about Mercury is the fact that it may harbor ice in a deep, dark polar crater. Ice on Mercury? How could this be?

All planets spin as they orbit the sun, and usually those spins have some harmonic resonance, thanks to gravity. This means that Mercury’s spin has slowed to the point that for every two times it orbits the sun, it rotates three times. A day on Mercury lasts about 176 earth days, baking the landscape for 88 days at a time from sunrise to sunset. The polar regions are the exception; they see little sun due to Mercury’s axis being nearly upright. It is deep craters in these polar regions that may harbor ice from a long past comet collisions or outgassing from Mercury itself.

Mercury’s curious spin has also led to the discovery that it may still have a molten core. Raw eggs tend to wobble more than hard boiled ones when they spin. That’s a good way to tell which ones have been cooked. Using that same principal, scientists have used radar to learn that Mercury wobbles more than a hard-boiled planet should wobble. This is surprising since tiny Mercury has had time to cool enough to solidify in the past 5 billion years. Its core is surprisingly large, as well. It makes up about 75% of the diameter of the planet. Such a large, dense core can’t be explained by compression, as it can in the cases of earth and Venus, so astronomers are curious to find out how Mercury accumulated such a great proportion of the solar system’s heaviest elements.

The Messenger spacecraft should be able to shed some light on these questions. The Mariner data was limited and up to now we have only had pictures of one side of Mercury. New pictures of before unseen parts of Mercury are streaming in, and soon this little world will tell us more about how the solar system formed.

There are many mysteries about Mercury, some of which Messenger will try to answer. But in the meantime, we can try to spy the tiny planet in the fierce glow of the sun. The evening sky of late January still has elusive Mercury visible very low in the west after sunset. In the morning, Venus and Jupiter will be together, shining brightly in the February pre-dawn sky. On February 4th, the waning crescent moon will join the party in the eastern morning sky.

Tuesday, January 15, 2008

Oceans of Life

I love the Great Lakes, but I have a new crush- the ocean. I just returned from California and the Pacific. Over and over, like the ticking of an endless clock, waves crashed on the beach, bringing evidence of life from its depths and splaying them on the shore. The ocean seems timeless. But it wasn’t always here.

Early earth looked a lot different from the planet we know today. Scientists think that when earth first formed, there were no oceans. As the planet was forming, outgassing of the crust, along with constant meteor and comet bombardment, slowly built up the water vapor that condensed to form large bodies of water. These first oceans were not the blue beauties we are familiar with. We call earth the blue planet because of our azure skies and violet oceans, but when earth was young it had red skies and greenish-grey oceans. The thick early atmosphere was mostly carbon dioxide, and the water was a cloudy stew of water and other chemicals, with lots of salt from volcanic rock erosion and dissolving gasses from the air. Evidence suggests that this stew brought all the right ingredients together to create self-replicating matter, or life. The oldest life forms we know are found along the ancient ocean shores. Stromatolites are the fossil remnants of ancient communities of bacteria, and it seems that microbial life ruled the earth for most of its history, as far back as 3.5 billion years ago.

Now we find microbes in the violent heat and pressure of volcanic vents, and miles high in the harsh outer layers of our atmophere. Our bodies are crawling with them, and it is microbes that we search for as we send probes to other planets and moons.

The origin of microbes is not understood. Perhaps the earth supplied the right ingredients herself, or perhaps they flew in on a dirty comet from outer space. As we learn more about how life formed, we gain insight as to where to look for it in the solar system. And the evidence points to water.

We’re already crawling over the surface of Mars looking for signs of water. We find a lot of evidence for its existence, but as we drill into the rocks and look for fossils, none appear. We’ve also sent a probe to Saturn’s largest moon, Titan. The probe found no watery oceans or lakes in its quick descent and painless death on the moon’s cold, remote surface. Instead, it glimpsed rivers and streams of liquid hydrocarbons, which may be home to other, unfamiliar life forms, but nothing we can recognize.

Jupiter’s moon Europa also intrigues scientists, since it is completely enveloped in ice, has a thin surface layer of organic molecules, and may harbor an entire ocean of liquid water beneath the ice. Scientists are hard at work in Antarctica, perfecting tools that can drill through miles and miles of ice and submarines that can explore the depths. They hope to send a probe to Europa to drill beneath the ice and peer below this frozen shield. Though the mission is currently on hold at NASA, someday we will launch a vehicle to the oceans of Europa to see if they hold the promise of life. Even if they don’t, we will learn more about the incredible specialness of life here on our home planet.

Until next week, my friends, enjoy the view.

Monday, January 07, 2008

The Space Club, Part II

1/13/08 – 1/19/08
by C.Zaitz

In our current climate of economic struggles, sometimes it’s hard to see the benefits of globalization. As Michiganders see jobs flying out the proverbial window to other countries, it’s hard to welcome the change. But it may be argued that the sharing of resources may be the only way to continue human and robot space exploration, and therefore help ensure the survival of our species.

Globalization is painful. Rich countries, superpowers even, may lose some of what they have to support countries that don’t have as much. Can a country, can a people, be that altruistic? I don’t know if compassion is anywhere in Darwin’s “survival of the fittest.” I don’t know that evolving the ability to share for a common good is necessarily going to help us survive as a species, much less get us to the moon or a nearby star. Maybe that’s why we don’t see aliens in Red Cross trucks patrolling our solar system.

The ability to launch space vehicles is the first level of space exploration. The second level is sending probes to other worlds. The Soviet Union sent the first landed spacecraft explorer to Venus in 1970. Prior to that, both the US and USSR had sent flybys to Mars and Venus, some successful, some not. In the 1990’s, Japan sent a probe to the moon, and then tried to send one to Mars. The first made it, the second didn’t. India also wants to join the probe club with a program to go to the moon and Mars. They plan on launching an unmanned moon mission in April of 2008. Meanwhile, nearly two thirds of the probes sent to Mars have failed. It turns out that sending probes to space is not the easiest thing to do. With a failure rate like that, it stands to reason that sending people to space is even more dangerous. So instead of secretly “cold-warring” our space programs, maybe our nations should share our resources. But can that happen? Perhaps the space race is fueled by competition, not compassion.

Level three of the space club, sending humans into orbit, has been reached by only three countries so far: China, Russia and the United States. The Soviet Union beat everyone in 1961, when Yuri Gagarin became the first human in orbit. The US, sweating bullets, followed by shooting John Glenn into orbit in 1962. China has recently gained entry to this level of the club by blasting Yang Liwei off to space in their own launch vehicle in 2003. This is a very elite club, but not as elite as the next level.

The twelve American men that walked on the moon from 1969-1972 are the only humans to step foot on extra-terrestrial ground. Many countries have a stated interest in going to that level, but the stakes, expense and danger to human life are so much greater than the other levels of the space club that I wonder if it will happen. Intense motivation is needed: perhaps motivation like a large asteroid heading our way, or a real visit from extraterrestrials. Or perhaps just the Helium-3 that we know the moon is loaded with. Whatever it takes, cooperation and compassion, or competition, I hope we can someday enjoy the next level of space exploration: stepping foot on another planet.

Until next week, my friends, enjoy the view.