I’ve been watching a really interesting series called The Universe. It’s one of the better space documentaries I’ve seen. This morning I watched the episode on moons, and it got me thinking.
When I was in school, there were nine planets and oh, I don’t know… maybe 25 or so moons, scattered through the solar system. Things have changed a bit since then. We’ve been to every planet except Pluto now, and there’s a spaceship on the way as I write this. If memory serves, it’ll arrive in about four years. (If you didn’t know, Pluto isn’t a planet any more. It’s a planetoid, or a dwarf planet, or a Kuiper Belt object. Ask Neil deGrasse Tyson.) Today we know that there are hundreds of moons, some regular and some irregular.
When I was in school, water on earth was a big puzzle. How in the world did it get here? Where did it come from? There were a few theories, but none of them sounded convincing, even to me as a school-child. I was taught that water was very rare in the universe. It turns out that I was taught wrong. We’ve found water all over the place in our own solar system. Jupiter’s moon, Europa, has a very thick coat of ice which probably has a liquid ocean underneath it. There’s water on Mars, too. Jupiter, Saturn, Uranus, Neptune, and Pluto all have water in their atmospheres.
And then there’s the Kuiper Belt. It was only discovered in 1992, but what a big discovery! It’s similar to the asteroid belt, but there’s one important difference. Many of the “rocks” orbiting beyond the gas giants are composed of frozen methane, ammonia, and water. Do those chemicals sound familiar to you? They should. They’re the main ingredients in primordial soup.
Mars is an interesting case. It has two moons, Phobos and Deimos. They’re both irregular moons, which means they look like asteroids that have been snagged by the planet’s gravity. We’ve done very precise measurements of their orbits and determined that Mars will be moon-less one day. Phobos is going to eventually crash into Mars, and Deimos is eventually going to go wandering off on its own. (Incidentally, earth’s moon has the same destiny.)
Jupiter is a moon magnet. It has at least 63 moons, many of them irregular. They orbit eccentrically at all sorts of distances and angles. Jupiter’s immense gravity is powerful enough that moons can orbit much farther out than any other planet.
What Does It All Mean?
Ok. I’ve been stringing you along and not getting to the point. What is so damned interesting to me about these moons? What can this possibly have to do with my blog’s theme?
I was thinking of Kavi and his quest for knowledge and realized that I have a perfect example from my life of allowing new learning to reshape and challenge old beliefs. What do these moons mean? Well, the irregular moons mean that planets do capture stray objects orbiting the sun. The decaying orbits of so many irregular moons means that planets do grow from the process of grabbing passing asteroids and Kuiper belt objects. The distinct difference between irregular and regular moons means that there are two ways that moons came to exist. The existence of water all over the solar system, in the Kuiper belt, and on various moons means that water on earth isn’t an unexplainable miracle.
In short, moons and the Kuiper belt are the proof that the current model of our solar system’s formation is correct. The planets did form by accretion. Water did come from the outer limits of the sun’s gravity. The chemicals necessary for the formation of amino acids are not rare at all. It’s not speculation anymore. Science and technology have given us first hand evidence of how our home came to exist. (At least, if we are wrong about this, there’s going to have to be a monumental discovery which will invalidate most of our beliefs about the universe.)
That’s all well and good, but there’s a bigger lesson in the moons. Our solar system doesn’t appear special in any particular way. When we turn our gaze farther out, we discover that our system is an insignificantly tiny speck in a galaxy that is in turn an insignificantly tiny speck in a universe filled with billions of insignificantly tiny specks. We’ve found that other stars have planets. Lots of them do, in fact. They all orbit following the same laws of physics that our planets do.
Here’s where it gets interesting. It’s normal to start thinking philosophically about “what it all means” when we think about the enormity of the universe and the apparent insignificance of humans in the whole picture. But let’s ask the question directly. What does all of this mean for humans?
My answer to that question is easy. I don’t know. I can’t think of one thing in this gigantic picture that points to humans in any way whatsoever. So I can’t very well answer the question, right? And that’s ok. Some questions are fine left unanswered. It doesn’t mean we can’t keep looking for answers. It just means we’re comfortable enough admitting that we don’t know right now.
This observation is problematic for some beliefs. The main reason for this is what the solar system does not point to. It does not point to a special act of loving creation directed towards earth and its inhabitants. Let me be clear — it does not disprove the existence of an act of loving creation. But it offers no support for the idea.
If we think about things historically, we get a clearer picture. The idea of a magic act of creation is fairly old. Almost every culture has a creation myth. But we need to notice one simple observation about creation myths: Not one culture knew about planets and moons when they invented their creation myth. Not one of them had any knowledge of the Kuiper belt, or accretion discs, or the existence of billions of galaxies.
Kind of makes you think, doesn’t it?
- Mars moon may have formed like our own (newscientist.com)
- Fourteen huge space rocks discovered beyond Neptune [Future Meteors] (io9.com)
- Unusual Facts about the Solar System (brighthub.com)
- Aug. 24, 2006: Pluto Deplanetized (wired.com)