From our closest celestial neighbor to distant objects that orbit planets, moons are pretty interesting. The more we learn about them the more interesting they become. Scientists are constantly looking at various moons as future projects, but why? What's up with moons?
Studying the moon has been part of the human experience for as far back as we can tell. Some of the earlier human recordings document the moon's phases and its alleged impact on life here. A long time ago the moon was thought to be a supernatural being that had control over the on-goings of things on Earth. Well, the early humans were not totally off, the moon does have an impact on Earth. Without our moon's gravity the tides on Earth would not be what they are, thus enacting a series of chain reactions that would make life as we know it quite different. As we developed our technological skills we started to understand more about our natural world. The moon went from being a supernatural being in the sky to a physical world that we could learn about, look at, study, and eventually became a place for us to land. Our experiences studying our moon have brought on some rather amazing technological changes. Neil Armstrong's famous first words on the moon mention how this accomplishment was a giant leap for mankind. This is true, the lunar landing involved more scientific power and technological skill than anything humanity has ever attempted in the past. The moon is very important to us humans though it orbits us from nearly a quarter of a million miles away.
Our moon, as wonderful as it is, is not the only moon of interest to scientists. The general topic of moons is pretty fascinating to the science community. There's much to be learned from these natural planetary satellites. For several decades the moons of Jupiter have been a hot topic in the astronomy community. Europa in particular. When space probes first passed the orbit of Europa we were given the first ever glimpse at those worlds, invisible to the naked eye but crystal clear with the use of space probes. Europa seemed to be particularly interesting because of its smooth surface. How can a moon have that smooth a surface? Our moon, the planet Mercury, our home here on Earth, and several other places that as solid objects seem to all have distance crater impacts from the billions of years of cosmic evolution and collisions. How is it that Europa does not? Well, the best theory that seemed to make the most sense was the Europa is comprised of a giant liquid ocean under the frozen surface. When an object collides with Europa it breaks the icy surface and sinks into the subsurface ocean. Shortly after the water at the top freezes and thus a smooth surface. This theory would involve the possibility of a much larger thought, if the planet is made mostly of liquid water, does that mean that for the past however many billions of years there have been opportunities for life to arise on the Jovian moon?
Recently the Hubble space telescope has spotted some interesting sights on the distant moon. NASA just announced that they had documentation of a geyser erupting on Europa. The stream of water vapor bursting out of the frozen surface was over 125 miles high! This is a bold discovery that brings up some interesting new thoughts on what this moon is capable of holding. First of all the geyser shows that there is indeed geological activity happening on Europa. This is not a dead world at all, the body is active. The other thing that scientists are celebrating is the identification of water vapor in this massive eruption. The moon does indeed appear to be a host to a substantial amount of water. So, the same question gets brought up again, if there's water on Europa is it possible that over the past billions of years life could have found a way to exist on Europa? Interesting thought, one that will require a lot more attention and studying. Another discovery that reinforces our need to study these distant objects.
Meanwhile, closer to home, the interest in our moon has not diminished at all. In 2013 we've sent several orbiting spacecraft to study various aspects of the moon ranging from lunar gravity to its atmospheric composition. In December of 2013 the Chinese National Space Administration took the words of Neil Armstrong to a whole new level. The giant leap for humanity has now been met with another Earthly being known for leaping, a rabbit. Not a real rabbit, but the Chinese space agency has just landed a lunar rover called Jade Rabbit. The objective here is to study the lunar surface topography and do a geology survey. The mission will also study lunar surface material compositions.
There are still many moons left to study but as we progress in our technology, the more we can do to reach these distant objects and further understand our natural world. Clearly with the recent lunar exploration projects the interest in moons is not waning.