Another wonderful image courtesy of the Hubble Telescope. This is galaxy NGC 4911, located some 320 million light years away. So that means we are seeing it as it was 320 million years ago. That was the Mississippian period on Earth, so called because the rocks from that area are exposed along the Mississippi River. Earth looked a little different then:
OK, a lot different. No grass, no flowers, no fruit, nothing but ferns and primitive such plants. There were some little lizard like things, animals were just beginning to move onto the land. Lots of bugs and spider like critters. The first flying insects were appearing. The food chain was rather primitive though. Bugs had just barely started eating plants, and other animals hadn’t started at all. Basically bugs eating leaf litter and decayed vegetation were the bottom of the food chain, and other stuff ate them. The oceans were strange too, while there were corals and such we would recognize, crinoids were very common, and trilobites were still around. The only octopus like thing was the nautilus. Lots of fish and sharks though, in fact the sharks then looked about the same as the sharks now. When nature hits a design that works, it keeps it. Although a point to be made is that while those sharks did indeed look very similar to today’s sharks, they did and do continue to evolve, none of the shark species extent then is still around.
On the plus side, there would have been no noxious pests whatsoever. No mosquitos, ticks, parasites, wasps, or anything even remotely unpleasant on land. No plants with thorns either. Just don’t go wading or swimming and everything will be fine. I mention these idyllic facts because according to Stephen Hawking’s most recent pronouncements, time travel is possible. And yes, in layman’s terms, there are paradoxes involved. In reality, no, there aren’t. That’s because whatever happened in the past … already happened. So a person can’t go back into the past and change anything. Even if someone does go back in time and murders their grandfather, all they will do is prove their granny slept around. I know sci fi movies have really muddied people’s thinking about these sorts of things; sadly, for the most part, sci fi movies are to science what cop movies are to real police work. Time travel may be possible, changing the past isn’t. Deal with it.
I digress, the thing about the Hubble image is that NGC 4911 is falling to its doom. OK, well, maybe not its doom, but it is falling into the Coma Cluster, one of the largest assemblages of galaxies in the known Universe. See the faint clouds around it? Those are stars that are being pulled away from NGC 4911 by other nearby galaxies in the cluster. Eventually NGC 4911 will lose its spiral arms, its satellite galaxies, most of its gas, and be converted into a boring yellowish elliptical galaxy. It will no longer be the stunning sight it is now. On the plus side, as the Universe expands, the Coma Cluster will stay together due to gravitational attraction, and even when the rest of the Universe recedes into invisibility, galaxies in the Coma Cluster will still be able to see other galaxies. Our galaxy on the other hand will appear to be sailing in an infinite endless void some 50-100 billion years from now.
The Coma Cluster has some mysteries of its own. It appears to be about 90% made of dark matter. Um, dark matter is stuff astronomers can’t see yet but can tell it’s there because of its gravitational effects on visible matter. I should blog on it sometime, if I ever understand it. This is a higher percentage of dark matter than we usually see in the Universe. And to deepen the mystery, the Coma Cluster has an X-ray source in it that no one can explain. Yes, something, something apparently larger than a galaxy, is kicking out a heck of a lot of X-rays in the Coma Cluster.
My point here, is that this is an image of a spectacular event, an entire galaxy being sucked into one of the most enormous structures in the Universe, where it will be completely transformed into an entirely new type of galaxy. And not only is this epic in scale, I mean “one of the largest structures in the Universe” is about as big as it gets, it is also epic in time. For NGC 4911 has been falling to its fate since before animals crawled out of the sea on Earth, and will still be falling after the Earth is a scorched oceanless desert some billion years from now. Quite a show.
And yet no one has even gotten around to naming NGC 4911? Yes, the Universe is so filled with wonders we can’t even count them all, let alone name them.
(The Hubble image above is more or less Public Domain and is being used, not for profit, legally: Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Acknowledgment: K. Cook (LLNL) et al. The image of Earth as it was about 320 million years ago is a public domain image. I wrote this post because it pleased me, I may switch back to that strategy for awhile.)