NASA/JPL-Caltech/Palomar
NASA, ESA, K. Sahu STScI
Posted on 03/18/2012 7:02:22 AM PDT by SunkenCiv
When astronomers talk about methods for finding exoplanets the list is relatively short. There is the radial velocity, or 'wobble' technique, which senses the motion of a star around a common center-of-mass with its planets. There is the transit technique, employed with great success by NASA's Kepler mission, and there are direct imaging and phase-photometry techniques -- challenging observations that seek the light being actually emitted or reflected from a planet. And then there is gravitational microlensing, the chance magnification of the light from a distant star by the distortion in spacetime due to the mass of a foreground star and its planets -- with distinctive 'blips' or cusps of brightness due to any worlds aligned close to the right place in the star's lensing field.
This form of gravitational distortion of the pathway of photons is called 'micro' because the typical arrangements and masses of stars results in tiny images; while the light of a background object may be greatly magnified we can't see its distorted image directly, its light merges with that of the 'lens' stars, mere thousandths of a second of arc from it. The gravitational effect of a planet around the lens star is effectively amplified when it is close enough to the zone of maximum magnification, the Einstein ring, but its effect is also only seen as an additional and asymmetric boost in photons arriving at our telescopes.
...The situation is rather different however for much closer stars. Not only can we obtain their 'proper motions' with careful high-precision astrometry, the zone around them that is optimal for magnifying a background object is that much bigger in angular diameter, it is 'meso' not micro.
(Excerpt) Read more at blogs.scientificamerican.com ...
NASA/JPL-Caltech/Palomar
NASA, ESA, K. Sahu STScI
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watching the little lights pulsate in the video, I can’t help thinking about an old saying about astronomy:
A mountain of knowledge built on a molehill of evidence....
Building a mountain out of a molehill is a good description of the geocentric model.
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