--- Joe Bauman <bau@desnews.com> wrote:
I don't want to flog a dead horse, but the blocking object doesn't have to block only the star. It could
block a huge swath of space to one side of the star,
as long as its edge just cuts out the star too. . . .
Joe, You might find these pages interesting. NASA Terresterial Planet Finder (TPF) Technology Milestone Page http://planetquest.jpl.nasa.gov/TPF/detectionMilestone.cfm NASA TPF Technology Plan (6.2 Mb) http://planetquest.jpl.nasa.gov/TPF/TPF-CTechPlan.pdf TPF Homepage http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm The problem isn't that much different from our amateur experience of predicting whether a binary star can be split. Whether a binary star can be split depends on the distance between the stars, _the contrast ratio between the stars_ and the Airy disk size of your telescope (which depends on aperature). By masking the central star, you increase the contrast ratio between the fainter secondary binary (or extrasolar planet). In the TPF, everything is working on much higher tolerances. As the NASA press release states, JPL has been able to make it work on simulated stars and planets in the laboratory. http://planetquest.jpl.nasa.gov/TPF/detectionMilestone.cfm TPF will consist of a visible light corongraph satellite and a compound, formation-flying infrared interferometer satellite. As you can see from the simulated pictures on this page - http://planetquest.jpl.nasa.gov/TPF/tpf_what_is.cfm - NASA does not seem to be trying to take what we would call a usual astrophotograph of a planet - rather they are trying to see the planet's signal in the diffraction rings and interference pattern of the light of the star. Wikipedia on a Coronagraph http://en.wikipedia.org/wiki/Coronagraph Another simulated TPF picture - http://en.wikipedia.org/wiki/Image:Coronagraph_starburst.jpg - Canopus56 __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com