Friday, August 08, 2008

Looking at what you can't see

My son, Evan, has been fascinated with astronomy since he was just two or three years old and first noticed the Full Moon. He saw it out a window in the back of our house and came running into our living room shouting, "The Moon...the Moon" and made my wife and I follow him so he could show it to us. After we looked at it and acknowledged it, we sent back to the living room. But he was so excited, he ran back in exclaiming, "The Moon, Mommy. The Moon, Daddy" and insisted we follow him in to the back room to see it with him again. We could not figure out what he wanted us to do but just watching it and agreeing that it was the Moon was not enough. We just didn't get it!

Over the years, we've bought him "space things." His grandmother (my mother in law) bought him a nice Meade telescope. We've bought him books and have taken him to a planetarium. For his last birthday, we bought him a set of the planets that you can blow up and hang from the ceiling (the set includes Pluto as a planet which gratifies Evan - he didn't like it when Pluto was officially demoted). He used his own money to buy the set of DVDs for the History Channel series The Universe. I also found a nice utility for his computer named Stellarium. The screens shots (below) come from Stellarium. It's free but amazing. It lets you enter your position on the Earth and shows you the sky at the time on your computer's clock. You can change the time to any date and time to see what the sky will look like then. In the screen shots here, you can see a red line curving up from the horizon. That is the ecliptic line where you usually find the planets (notice how far Pluto is from the ecliptic).

We've used Stellarium to predict what the skies will look like when we think the sky will be clear on certain nights. A few nights ago, we noticed that Mars, Saturn, Jupiter, Pluto and Neptune would all be "visible" on one evening. The top screen shot shows that part of the Stellarium display. Notice that it allows you to "draw in" the constellations and writes in the names of stars of a certain magnitude (you can adjust this setting along with tons of others).

Now, of course, we knew we wouldn't be able to actually see Neptune and Pluto. But being able to know that Neptune and Pluto were out there in the direction we were looking was fascinating. We took our dog, Charlie, with us and he had no idea what was going on. It was just a big adventure for him to go out in the car at night and be with his people. Charlie enjoyed sniffing around while Evan and I let our eyes adjust. As time went on and it got darker and we saw more and more stars, it almost seemed as if we just might get to see Neptune and Pluto after all. Maybe if we just relaxed and stared long enough, we'd see them glimmering out there. I remember reading a novel called Starmaker by Olaf Stapledon. It starts with a man laying down on a hillside to look up at the stars. As he gazes out into space, he finds the stars seemingly coming toward him. Then he realizes that he he has left the earth and is speeding out through space toward the stars. This begins his epic journey through many worlds and many universes.

Evan mentioned to me that it takes about an hour for the light reflected from Saturn to reach us. We figured the light from Neptune and Pluto would take a really long time and, after assuming the closest approach of each to the earth, we were right. It takes about 6 hours for the reflected light from both (their orbits cross and sometimes Pluto is closer) to reach Earth.

Well, it turns out that tonight, even Venus and Mercury will be visible (if only briefly because they are near the horizon and will be tough to see against the sun). The second screen shot shows that (notice the red 'W' centered on the bottom, that shows you're looking West).

While I was writing this, something from what I learned in high school seemed to be nagging me about whether you are supposed to capitalize Earth, Moon and Sun. At first I did. Then I changed them all to lower case. Then I decided to look it up. It looks like it's a confusing area even for the experts. As I interpret the "rules" I found, you don't capitalize "earth" when you're speaking about "dirt" but you do capitalize it when speaking of it as the planet Earth. So, I've gone back through the whole article and tried to do it correctly. Complain away if you think I am wrong.

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