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Gravity-Bent Starlight Reveals a New Planet
dfab writes "The first experimental proof of Einstein's general theory has been revamped to discover planets around distant stars. Yesterday astronomers announced that a new technique called gravitational microlensing has found a star that hosts a roughly Jupiter-sized planet in a roughly Jupiter-sized orbit by observing its effect on the light from a bright star beyond that planetary system. See the NASA report or the gory details."
Space.com also had an article about this yesterday. It gives a little better timeline to when it will be available to check low mass stars in the future, as well as doing a comparision on other extrasolar planetary detection techniques.
For those who want a quick excerpt of the science:
Gravitational microlensing uses a distant star (or other massive object) to bend light the same way as a lens would. If that star is perfectly aligned with an even more distant star (from our perspective) then the lens will call the more distant star to brighten, at least for as long as the alignment lasts.
The brightening comes with a spike (from "caustics" which are like irregularities in the lens), as the alignment gets good and them bad again. If you see a second, smaller spike, or an unusual extra image, that's evidence of a planet.
I'm not sure how you distinguish planets from weird caustics.
Note: this technique is good for detecting planets with long-period orbits, whereas the doppler-shift techniques are lousy for that, because they only work if the planet's revolution period is small (like in days).
Um, I think you're getting a bit confused - that's a completely different experiment, entirely unrelated. This is just a load of clever deductions based on some cool telescopic images, revealing a distant planet. The only connection is they both make use of the gory details of Einsteinian physics.
;-)
As far as I know, the satellite you're thinking of has to sit up there for a few months yet, so that we can see if it's moved by a few gazillionths of a millimetre or something - I can hardly wait!
Not that experiment. The one they are refering to is the one about watching stars during solar eclipses, and they are in the wrong place due to the sun's gravity bending the light. The one you are thinking of it completely different, and is about frame-dragging.
This doesn't seem like a reliable method, because it requires a star to be right behind the one you want to find a planet around, which must be quite unlikely, unless I'm missing something.
In fact, having just scanned through the article, they do mention that problem:
"Because the effect works only in rare instances, when two stars are perfectly aligned, millions of stars must be monitored."
The lensing bends a very tiny amount of the supernova's output - It doesn't work exactly like a lens, per-se. It only focuses a ring of light around it on the focal point (us). The light passing closer to the sun that that ring is deflected to far, and focuses before it reaches us, and the light passing farther out doesn't get bent enough and focuses "behind" us. The extreme distances add up, and the lensed supernova will be much brighter than it normally would, but it still wouldn't be dangerously bright.
Furthurmore, it would have to be on a line-of-sight with a lensing star and us. Supernovae aren't exactly common on the cosmic time/space scale, so this is very unlikly.
We're probably in more danger of a star too close to us going supernova than getting caught at the wrong end of a celestial ant roaster.
Ummm, I'm guessing you are referring to Gravity Probe B?
Not only is it going to take 1-2 years to test the theory, it hasn't been launched yet. It's new\rescheduled launch date isn't till April 19, 2004.
So to answer your question of what happened to the results??
It's hard to give results on a project that hasn't been launched yet.
Read more about this project here.
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Not really... microlensing causes an increase in the brightness of the star, not a change in the apperent position. Although you've drawn a nice picture of gravitational lensing. (see, for example, einsteins cross)
It's not wasting time, I'm educating myself.