I'm sure there are better explanations available, but if you're reading this you're probably interested in what I think I'm doing.
When people think of astronomers, they think of them as looking at the sky themselves, or taking pictures of what they could see if they looked at the sky long enough. However, our eyes are limited to seeing a very small portion of the total amount of light available. Light comes is a vast spectrum of energies, from low energies such as the radio waves that carry our information, to the microwaves that cook food and make cellular phones possible, all the way through the ultraviolet light that causes skin cancer and to the high-energy x-rays that pass straight through our bodies to produce medical images. Just as we encounter all these various forms of light everyday, so also the universe is filled with light of all sort that we can't see without special devices.
The project I am working on looks at the x-rays that come to us from distant stars and galaxies. These are produced some of the most violent interactions that we know of, in regions where a normal star is interacting with a neutron star or a black hole.
The information that we can gather tells us the specifics of the interactions that create the x-rays, as well as information about how fast a neutron star is spinning (much like the earth rotates on is axis), or whether the neutron star has a strong magnetic field, or even whether the the source of the x-rays is the area around a black hole.
The information gathered is not especially practical, but it provides the information theorists need to test and develop theories about the fundamental laws of nature in extreme cases. The knowledge gained will take many years to find applications, if ever, but it brings us closer to understanding how the world we live in works, and I feel that this alone is sufficient motivation for scientific study.
Feel free to mail comments to: muno@mit.edu