Word: planet
(lookup in dictionary)
(lookup stats)
Dates: during 2000-2009
Sort By: most recent first
(reverse)
...During the 1990s, sky surveys revealed that these puny stars are as thick as ants at a picnic, accounting for up to 70% of all the stars in the Milky Way. Because an M-dwarf is so faint, its habitable zone is much smaller, so any planet that falls within that zone would be much closer to it than Earth is to the sun. And that, says Harvard astronomer David Charbonneau, gives planet hunters a huge advantage. "Basically," he says, "it lets us cheat...
Rather than looking for a stellar wobble, Charbonneau and others are watching red dwarfs for signs of their light subtly dimming as an orbiting planet passes in front of them--a sort of mini-eclipse known as a transit. "If an Earth-size planet in an Earthlike orbit passes in front of a star like the sun," he says, "it dims the star by 1 part in 10,000 or even less." Since a habitable planet around an M-dwarf is much closer--about 7 million miles (11 million km) away--the transit lasts significantly longer. And since the star...
...eight 16-in. (40 cm) telescopes on Mount Hopkins, near Tucson, Ariz., and pointing them over and over at the 100 closest M-dwarfs to see if their light dims in a repeating pattern. If it does, he won't have long to wait: a habitable M-dwarf planet would have a "year" only three or four days long, so transits would happen all the time. Things will get even easier in 2009, when NASA launches a satellite called Kepler. Soaring above our planet's murky atmosphere, it could spot Earthlike planets transiting across the faces of stars...
...silhouette strategy for planet hunting will not replace the wobble-watching method. Indeed, red dwarfs make that method easier and faster. "M-dwarf stars are small," says astronomer Geoff Marcy of UC Berkeley, one of the discoverers of 55 Cancri's newfound planet. "That means planets can kick them around more easily." And all that means the first twin of Earth might really be found before long--and the discovery of life on other worlds could get a whole lot closer. The 55 Cancri Family of Planets [This article contains a complex diagram. Please see hardcopy of magazine.] A SIMILIAR...
...centuries-old debate: how do some nations attain long-term economic growth and an ever higher standard of living while others don't? What determines whether people in your part of the planet live in McMansions, mobile homes or mud huts? In the 18th century, proto-economist Adam Smith pointed to the transformative effect of the division of labor. In the 19th, David Ricardo highlighted the benefits of trade. In the 20th, Harvard University's Michael Porter made the case for industry clusters. Geography, physical capital, technology, worker education--they've all taken a turn as the supposed silver bullet...