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Hubble Finds Double Einstein Ring
Einstein Duble brings us news that astronomers using the Hubble Telescope have discovered an extremely rare double Einstein Ring. Occasionally, galaxies or other bright objects are located in such a way that they are behind another galaxy when viewed from Earth. When light from the further galaxy passes a sufficiently massive closer galaxy, the path of the light is bent inward from all sides, creating a "ring" effect. In this case, not one, but two galaxies are directly behind the foreground galaxy, so the gravitational lens produces two distinct rings. Quoting Presscue:
"The distribution of dark matter in the foreground galaxies that is warping space to create the gravitational lens can be precisely mapped. In addition, the geometry of the two Einstein rings allowed the team to measure the mass of the middle galaxy precisely to be a value of 1 billion solar masses. The team reports that this is the first measurement of the mass of a dwarf galaxy at cosmological distance (redshift of z=0.6)."
This is a prime example of the kind of useful knowledge that can be gained with projects like Hubble.
Libertarian Leaning Political Discussion Forum.
"Wheres my flying car though?"
They're called 'airplanes' and we even have a place to park them called 'airports'
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One of the cool implications becomes clear if you realize this means our galaxy is the 4th galaxy in a line with these three. To someone standing on a planet in that backmost galaxy, 11B Ly away:
...
* The one that's the "foreground galaxy" to us would be the inner ring.
* The one that's the "first ring" to us would be the foreground galaxy for them and
* The Milky Way would appear as the outer ring!
Actually, that's not the case. I'll give you a hint. The reason is because of something the guy these rings are named after, figured out. These galaxies aren't aligned. They just look that way from our perspective. From the other direction, it's extremely unlikely these 4 galaxies ever aligned, as odd as that sounds.
It seems to me that there must be lots of Double Einstein Rings out there, probably millions of them. We're just not standing in the right place to seem most of them.
If the galaxies look aligned from our perspective, they will look aligned from theirs. The inverse path
of the light will be exactly the same since the path is dictated by the perturbation of spacetime.
A witty
These things line up in space-time as follows: Galaxy 1 is on the line 11 billion years ago, galaxy 2 is on the line 6 billion years ago, galaxy 3 is on the line 3 billion years ago, and the Milky Way is on the line right now.
This does not mean that the reverse is true. It does not mean that there is a line that the Milky Way was on 11 billion years ago, and galaxy 3 was on 8 billion years ago, and galaxy 2 was on 5 billion years ago, and galaxy 3 is on now. Why not? Because galaxies move.
Still, even if not technically correct, it was a really awesome thought by the OP...
Don't worry, we can pay for the whole thing by leaving Iraq one or two days earlier. And plus, if you look at it from the financial angle, a space-industrial complex is just as good of an excuse for corporate welfare handouts as the military-industrial complex. The only difference is that if we spent $300 Billion a year on science, we'd probably get something good for humanity out of it.
It's sad that spending money to unravel the secrets of the universe is sneered at (see parent) while large numbers of people and entire news networks (not necessarily including parent) champion spending trillions of dollars to keep poking the middle east hornet's nest (And apparently think that if we keep poking, the hornets will get tired and give up).
Layne
for this to occur requires four galaxies to be very close to being colinear, and we have to be in one of the endpoints. Looking at the picture though there are several galaxies visible so I suppose they have quite a few to look at for this. I wonder just how rare it is? As in, is this the first one discovered? I'd asume if there were any other known double E rings it would have been mentioned in TFA. Hard to say how rare something is when you only have one of them to go by.
I work for the Department of Redundancy Department.
The measured mass of a galaxy useful? On its own, maybe or maybe not. Yet through this fortunate alignment we were given the chance to get information that, for lack of a better word, helps us 'calibrate' our astronomical tools.
The universe is understood by using phenomenae like this to test our theories and provide a sort of astronomical 'yard stick' by which we can measure other objects. Objects that without this yard stick would be less well understood. One discovery is built upon another until, one by one, they form the sum of our understanding.
So why not go out and measure the mass of that little rock in your backyard? Wouldn't it be amazing to discover that it had a density of 19.3 g/mL?
Out of modpoints but really liked a post? 1BDkF6TtmmeZ3yqXbz9yhdYVqRYnwFoXDj
I am sure some people wondered in 1600s 'why is that newton guy researching gravity he is such a fool, I know if i drop an apple it falls. What does it matter how fast it falls, that won't help my crops grow.'
There is no useless knowledge. There is knowledge we don't know how to use yet but no useless knowledge. Time will show, determining mass of a galaxy might turn out to be an essential calculation 300 years from now on, given civilization continues to evolve until then.