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Largest Lens Ever Discovered
K Tanmay writes "A team of Astronomers have found a natural lens capable of resolving details as fine as 10 microarcseconds across - equivalent to seeing a sugar cube on the Moon, from Earth. The lens comprises of a cloud of interstellar gas, and works on the principle of scintillation; where the clumpiness inside a cloud of gas creates a density change thus bending and focusing the light. This technique, dubbed 'Earth-Orbit Synthesis', will be first used to study black holes in distant quasars, so don't expect spectacular wallpaper replacing images. There's also an interview with Dr. Hayley Bignall, an astronomer from the Joint Institute for Very Long Baseline Interferometry in Europe (JIVE), where she discusses the concept of using interstellar scintillation to get observations that we could never measure from here on earth." Update: 02/22 18:23 GMT by T : That wikipedia link had led to the wrong place; here's the definition for arcsecond if you still want to read it.
What is a quasar? I've never really had a satisfactory explanation for this.
Maybe we need a new method for determining the distance between "scintillation" and "arcsecond".
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Alright! Now we can see the stuff we left on the moon to prove to all of those skeptics. Seriously though, I was just reading about this a couple of weeks ago and they said that no current telescope technology can resolve objects as small as the lunar rover on the moon from earth.
If we can't see a sugar cude on the moon right now, so how can we tell how this lens is focusing if at all? A few small defects in hubbles lens blured it bad, some thing this big would have alot of area for defects. to me that seams like it would make a very bad lens. So my real question is? how is this usefull?
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The caption to one of the illustrations reads:
At some times of the year, both the Earth and the cloud 'lens' are moving in the same direction, and the observed variations are slow, but six months later they are moving in opposite directions and the variations are fast.
while the illustrations clearly shows a a wave which is of constant frequency but of varying amplitude. I believe the caption is correct...
And a related complaint: what is the point of including a picture of the ring nebula with the caption:
The Ring Nebula, although not useful imaging through, has the suggestive look of a far-away telescope lens.
I guess when you can't come up with any images actually related to the topic, you might as well throw in some pretty Hubble pictures for those who aren't going to read the text anyway.
... wonder how long it takes to figure how to combine array of these to create virtual super-scope ( like DARWIN) and start watchin' exoplanets.
It will be interesting to see whether such phenomena are actually found.
Some scientists have theorized that quasars are *not* distant galaxies, but stars with a peculiar lens-effect that causes a very large perceived red shift.
Part of the problem with the idea that the red shift is a doppler effect is that the observed quasars are apparently all in a relatively spherical arrangement about the Earth, thus implying that the Earth must be the center of the observed universe.
It could be that this is just an artifact of observation: we see the quasars as equidistant from Earth because we are perceiving them from Earth. But it is very strange and implies a problem with the theory.
A paper on this subject is available.
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Quasars are bright objects that are much larger than stars (a few light-days across) and are observed in the distant universe (that is to say, they existed in the distant past and the light from them is just reaching us now).
There is a theory that the quasars are a type of active galactic nucleus, powered by black holes. Matter falling into these black holes would be accelerated to enormous speeds and superheated, producing lots of radiation. Plenty of this radiation would be given off before the matter got so close to the black hole that the light could no longer escape.
This theory, if true, could account for the brightness of these objects. It's thought that a giant black hole sits at the centre of many galaxies (including our own), but in older galaxies the centre is not bright like a quasar because the black hole has already gobbled up most of the mass close to the centre of the galaxy. We see some galaxies that have active nuclei but aren't as bright as quasars, but they might just be quasars viewed from a different angle.
I wasn't referring to it in terms of being black and so...
Even if you look at Hubble's images, they're no so spetacular.
Try putting in context, largest lens, images...
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High precision timing of millisecond pulsars (which accounts for every single rotation of a pulsar over the course of several years) can make observations with astrometric (i.e. positional) errors of several micro arcseconds.
An excellent example was published in Nature in 2001. Here is a preprint. The work describes the timing of the nearby (~450 lt-yrs) millisecond pulsar J0437-4715. The proper motion (movement across the sky) and parallax (apparent motion on the sky due to the earth's orbit) of the pulsar were measured to extreme precision, and a new test of General Relativity was also given.
PS: IAAPA (I am a pulsar astronomer)
I studied I.S. a little bit awhile back. Carl Sagan did some work on scintillation; the scintillation effect can pull out a distant radio signal by gathering in rays from a lot of different directions and accidentally throwing them right at you. The famous WOW signal, I believe, was investigated as an example of scintillation from a big cloud much like the ones described in the article.
It is interesting to see this technique used to do radio astronomy. Most of the times when you encounter a natural lens, it is sufficiently weird that you use the observation to analyse the lens itself, and not what it happens to be magnifying. Gravitational lenses are interesting in large part because you can try to figure out the distribution of dark matter in the lens itself -- and not because you can use it to "see into" the object being lensed. These lenses are not exactly perfect optics -- they're more like balls of glass, which distort and differentially magnify something behind.
But I'm not as familiar any more with radio astronomy. It is definitely possible that we understand enough about the properties of the ISM that the more interesting problem of figuring out the properties of the background object is open for work. Very cool!
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I don't really get how they put the image(s) back together. The clouds are not perfectly round and it is like observing one point at a time at best, and hard to know what point it is because the "lens" changes what it is looking at. I suppose the motion of the cloud and earth through space will give a "scan-line" like sample, but it would still almost be like trying to figure out what the sun looks like by studying the sparkley net-like wavey patterns at the bottom of a swimming pool.
Table-ized A.I.