On Oct 17, 2015, at 11:17 AM, Larry Colen <l...@red4est.com> wrote: > Marco Alpert wrote: >> http://www.alpert.com/marco/photo15/peso21.html >> >> Okay, not really. It’s actually the laser that creates the “artificial star” >> for Lick Observatory’s amazing adaptive optics system: > > Very cool. I've never seen a red beam be visible in clean air, just the > green ones. But maybe that's only because the green ones are currently the > only cheap ones powerful enough to have enough light scatter through clean > air to be visible. > > Was it visible to the naked eye? Or was that the result of a longer exposure?
It was visible to the naked eye, but not nearly to the extent of the photo. It was about a 5 second exposure. > >> https://en.wikipedia.org/wiki/Laser_guide_star > > There is an amazing photo in that article: > https://en.wikipedia.org/wiki/Laser_guide_star#/media/File:Laser_Meets_Lightning.jpg > > I wonder if the laser ionized the air enabling that lightning strike. They > wouldn't be doing much astronomy with the sky that cloudy. Indeed. If the photo weren't from a scientific organization, I’d suspect Photoshop. The longer caption does say the lightning strike was actually quite far away from the observatory. >> Comments, as always, welcomed. >> >> -Marco >> >> --------------- >> http://www.alpert.com/marco > > -- > Larry Colen l...@red4est.com (postbox on min4est) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
