Tuesday, August 08, 2006

Let there be light


This Hubble photograph of two galaxies passing in the night (click to enlarge) is just one of hundreds of photographs that change the way we view the universe. Together they constitute the contemporary equivalent of the creation myths of our ancestors, although on a vastly more inspiring scale. Peruse this visual document
here
.

The two galaxies are NGC 2007 (the larger) and IC 2163 (the smaller, about the size of our Milky Way). The smaller galaxy seems to be passing behind the larger one in a near collision. Their mutual gravity draws out streamers of stars.

Stars within galaxies are far apart compared to their size. Think of a grapefruit in Boston and another in San Diego. The galaxies in the photo contain hundreds of thousands or even trillions of stars. The galaxies themselves are rather closer together compared to their size. Think of a half-dozen saucers floating around in a space the size of your living room. Stars seldom approach each other. Galactic collisions are not all that rare.

At the end of Walking Zero I use this analogy: If the 200 miles of the prime meridian track across southeastern England is taken to represent the distance to the most distant objects we observe with our telescopes, then a couple of steps would take me across the Milky Way Galaxy. A mile or so of walking would take me to the colliding galaxies NGC 2207 and IC 2163.