U.C. Berkeley Astronomy professor Geoff Marcy spoke to the San Mateo County Astronomical Society on the campus of the College of San Mateo last Friday evening, February 3rd.
Marcy’s been a Science Celeb since 1996 when he was featured in Time Magazine, along with Paul Butler, because of their work which identified a planet not dis-similar to our Jupiter circling a star named 55 Cancri, a discovery that offered hope there might be an Earth-like exo-planet in that neighborhood as well.
Now, 16 years later Marcy and collegues are grabbing headlines again. This time it’s based on their recent announcements that several exo-planets much closer to the size of our Earth have now been ‘directly’ observed by NASA’s Kepler Telescope.
Launched in March 2009, and operated by NASA Ames Research Center, Kepler orbits around our sun in an Earth-trailing orbit that yields a super-unimpeded view of the universe.
Marcy told his audience last Friday that Kepler has revealed “lots of planets” in its brief lifetime, over 2300 planets residing in 170 different planetary systems within that fraction of sky the telescope’s been peering into with its unblinking 1-meter parabolic mirror for almost 3 years – a 10-degrees-squared viewing area near Cygnas with 150,000+ stars visible therein.
The team at U.C. Berkeley, in conjunction with NASA and the Keck Observatory in Hawaii [operated by UCB], has seen each of these 2300+ planets by tracking the periodic dimming of its associated star – from very bright to 99.99% as bright – as the planet passes into the line of sight between Kepler’s ‘eye’ and the star under observation.
Marcy said, “We ascertain the planet’s presence and size by the periodic drop in brightness of the star its orbiting.”
Of course, planets that don’t happen to traverse that line of sight would not be seen, and neither would planets that haven’t passed by in the last 3 years since Kepler’s been looking.
Marcy acknowledged that those “objects of interest” probably make up the bulk of the hypothetical planet population: “We’re undoubtedly missing 99 percent of the planets. Nonetheless,” he said multiple times, “it’s an extraordinary moment in history!”
Particularly because last December’s announcement from the Kepler-Keck team that several planets as small as 2x Earth’s radius were observed, has now been eclipsed by the team’s subsequent announcement that two planets approximately the same size of Earth have now been spotted – albeit, whipping around star Kepler 20 at a pace that would rip you and me apart at the seams, with orbital transit times of a breathtaking 6.1 and 19.6 days, respectively!
Okay, Marcy acknowledged, so these places aren’t exactly habitable. Planets Kepler 20e and Kepler 20f are too close to their sun, hotter than Hades, with surface temps exceeding 2000 degrees C, and of calculated densities [based on size and orbital period] that preclude the existence of water – but the hunt has just begun, and the significance of what Kepler’s seen so far is totally profound.
Marcy said the Apollo Moon landing, the sequencing of the Human Genome, and the first sightings of Earth-sized planets are all massive milestones in human history, with this last perhaps being the greatest, because we may be on the verge of finding habitable Earth-like planets – ones that reside in the legendary Goldilocks Zone.
And why does that matter?
Well, apparently we’re lonely here on Planet Earth and can’t wait to find other life forms living outside of our own puny sphere of existence. Or, we’re killing our current Earth and need to trade it in for a cleaner model.
Either way, this is the stuff of dreams – the stuff that drives Sci-fi enthusiasts, amateur astronomers, and uber-nerds to spend Friday nights hanging out in the lecture hall. After his talk, Dr. Marcy happily answered questions from all of them.