Thursday, January 09, 2014
"Alien Planets Revealed" on PBS Nova
PBS Nova’s “Alien Planets Revealed” offered illustrations of possible alien life as any documentary since NatGeo’s “Extraterrestrials” (2005) or Discovery’s “Alien Planet” (reviewed here May 4. 2012). The link is here.
Space instruments that detect slight perturbations in starlight can now estimate the size and mass of extrasolar planets.
There’s a sunlike star 600 light years away with a planet with about 2.5 earth diameters, thought to be a waterworld, with oceans a thousand kilometers deep. But 1200 light years away there is a sun-like star with a planet only slight larger than Earth. The slightly greater gravity could encourage large land animals to have more legs, and reduce the effect of bipedalism.
There are many more small red dwarfs than there are stars like the Sun, including a few within 20 light years of Earth. A planet in the ‘Goldilocks Zone” around a red dwarf would have to be close enough to be tidally locked, one side facing the sun and revolving quickly. Nevertheless, cold air would sink on the dark side and rise on the warm side, producing strong winds that could keep the planet more consistent in temperature than one would expect. The documentary speculated that plants would be black, because they would need to absorb enough light for photosynthesis. Land animals might be more static, like “land whales”. Life might accumulate in the “termination zone” or twilight area, where weather is the mildest. There would seem to be an eternal red sunset.
Even though there may be millions of “Earths” in the Galaxy, it isn’t necessarily true that intelligent life with culture like man’s is common. Sharks have ruled the oceans for 400 million years without having to be smart; they’re content with “free fish”. On the other hand, primates (humans) and cetaceans evolved separately, and the social structures of some carnivores (wolves, dogs, lions) show the beginnings of human-like intelligence. The ability of some animals to “self-domesticate” (dogs and cats) shows that once intelligence gets started, it can progress quickly.
There would be the possibility that super civilizations around sun-like stars could colonize the planets around M-stars, a premise followed in Ridley Scott’s “Prometheus” and “Alien” movies.
Experts included Knoll, Dartnell, and Charbonneau.
Wikipedia attribution link for Beta-Pictoris.