How cool is this???? I saw it on my Daily Nasa Photo, and had to read more about it. Wanna know how the galaxy on the right obtained it's current composition? Read this...it's ridiculously amamzing!!
(taken from the Nasa webpage)
Just a few days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a particularly intriguing target, a pair of gravitationally interacting galaxies called Arp 147.
This image scores a "perfect 10" both for performance and beauty, demonstrating that the camera works exactly as it did before going offline.
The two galaxies are oriented so that they appear to mark the number 10. The left-most galaxy, or the "one" in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, resembling a zero, exhibits a clumpy, blue ring of intense star formation.
The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, (go back and read that part again and try not to let your jaw drop) a propagating density wave was generated at the point of impact and spread outward. As this density wave collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation.
The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation Cetus, more than 400 million light-years from Earth.
Image Credit: NASA, ESA, and M. Livio (STScI)
Comparing galxies to pebbles...i can't even wrap my mind around that.