Behold the cosmic snake
If you can't wrap your head around every aspect of Einstein's Theory of Relativity, that's understandable. Neither can I. But when it comes to massive objects warping the fabric of space — one of its more dramatic predictions — the Hubble Space Telescope help us make sense of this bizarre phenomenon.
Hubble recently captured a photo of the Cosmic Snake, a distant galaxy peppered with clumpy regions of intense star formation (blue dots and dashes along its length) warped by the effect of gravitational lensing. Although it appears to be slithering between normal-looking galaxies, the giant object is actually far behind a foreground galaxy cluster called MACSJ1206.2-0847 in the constellation Corvus.
Light from the distant galaxy arrives at Earth after passing through the powerful gravitational field of the intervening cluster. Picture the field as a giant lens that focuses and brightens the light of distant objects in the background into images, similar to what an optical telescope does except with added distortion.
Of course, this metaphor only goes so far. In reality, there's no lens at all, only light coming to a focus after following the contour of the bowl-like depressions made by the cluster in the 4-dimensional fabric of space-time. Instead of traveling in a straight line, the way we usually think about light's direction, it weaves and bends according to the local fabric of space-time.
Here's the killer thing. Were the cluster not there, we probably wouldn't even see the Snake, but thanks to lensing, it's not only plainly visible but smeared into a whimsical shape. Sometimes gravitational lensing can even produce multiple images of the object as light is bent in different directions around the foreground cluster. Using Hubble, astronomers recently looked at five such images of the Cosmic Snake, each with a different level of magnification. Using this technique, the galaxy and its features could be studied on different scales. The highest-resolution images revealed that giant clumps in remote galaxies are made up of a complex collection of smaller clumps, which contributes to our understanding of star formation in distant galaxies.
• Visit bit.ly/2zUOgFK to get an inkling of what space-time's all about.
Bob King is the Duluth News Tribune's photo editor and an amateur astronomer. Read more on his blog at astrobob.areavoices.com. Astro Bob's new book, "Night Sky with the Naked Eye," is all about finding constellation, planets, satellites and other night sky wonders without a telescope. Pick it up at the Duluth News Tribune and area bookstores; or order it at Amazon.com and BN.com.