“Earth-sized planets” are becoming the new “Danica moving to NASCAR.”
Remember when there was a new “story” about Danica Patrick’s impending move to NASCAR every other day? None of them ever had anything new to report, but the stories kept right on coming.
The Milky Way hosts at least 17 billion Earth-size alien planets, and probably many more, a new study reveals.
Astronomers have determined that about 17 percent of stars in our galaxy harbor a roughly Earth-size exoplanet in a close orbit. Since there are 100 billion or so stars in the Milky Way, that works out to a minimum of 17 billion small, rocky alien worlds, or an Earth-size planet around one of every six stars.
Wow. Seventeen billion of them. But:
… 17 percent of stars have a planet 0.8 to 1.25 times the size of Earth in tight orbits, with periods of 85 days or less.
Eighty five days or less? That’s the big story? Those are the Earth-like planets we’re supposed to get excited about? Mercury has an orbit of 88 days. Are we really calling a planet as close to its sun as Mercury is to ours Earth-like?
Mercury’s surface experiences the steepest temperature gradient of all the planets, ranging from a very cold 100 K at night to a very hot 700 K during the day.
That’s 280 degrees below zero to 800 degrees above zero, for those of you who only speak English.
Mercury also has no atmosphere, which also factors into its enormous temperature swings. An Earth-sized planet might be more likely to have atmosphere, having more gravity with which to hold it.
Still, even with atmosphere, would a planet that close to the sun be a place humans could set foot?
Is it too much for me to ask: how many with orbits of around… oh, I dunno, let’s just pull a figure right out of thin air… 365 days? Y’know, like Earth.
Please wake me, somebody, when Danica really does move to NASCAR.