The Gravity Of It All

Friends,

Gravity is pretty important...without it, we fly away, for one. We also would not be able to enjoy the ocean tide, since it is gravity from the pull of the moon which triggers tidal force -- and this is not to mention that the University of Alabama would have to find a new mascot :-). This is the main reason that we have not yet been able to send people to Mars; we have not perfected an artificial gravity environment that would sustain human life for the several years' journey (and back) that would be required -- weightlessness wreaks havok (atrophy) on the human body over extended periods of time. We are okay to be able to get astronauts to the space station and even the moon for shorter periods of time. (In fact, Sunita Williams just completed the longest stay by a female astronaut at the space station -- 195 days). This is all fine and dandy around the environs of earth, but when we go out into deep space, we begin to understand what a monster gravity can become. The gravity well of a black hole (where not even light cannot escape) is so powerful that it can pull stars and planets apart. Something far more impressive occurs on a galactic scale, where a process called "tidal stripping" can occur. This is where a smaller galaxy comes into close enough proximity with a much larger galaxy that the larger one pulls the smaller one into an orbit where it then begins to pull it apart. The larger galaxy strips stars from the smaller one and absorbs them into its own domain. Amazing! If you think about gravity from this perspective, it gives it a whole new weight...ha ha.

Don