The announcement Wednesday by NASA’s Jet Propulsion Laboratory details one of the most important astronomical discoveries ever: scientists using the Kepler orbiting telescope have found indications that planets are abundant in our galaxy and many —- including Earth-size planets —- are in their stars’ habitable zone.
What does it mean? I’ll stick my neck out and say it: we are not alone. We can’t be, with these odds.
Press releases by JPL, Pasadena, said Kepler has discovered hundreds of new planet candidates, ranging in size from close to Earth’s to giants larger than Jupiter, and in density anywhere from that of polystyrene foam used in beverage cups, to iron. Sixty-eight of these are about Earth size, the first such exoplanets ever found.
The habitable zone is the region that’s far enough from a star that liquid water wouldn’t boil off, yet close enough to its warmth that an ocean wouldn’t freeze — In other words, neither too hot nor cold for life as practiced on Earth.
A caveat: the new findings are only candidate planets, which still must be verified. More studies, gathering further information as planets continue to eclipse their host stars, are needed. But the indications are good.
Since March 2009, Kepler has been examining 156,000 stars in the same small section of the Milky Way Galaxy — a patch making up only about 1/400 of the sky.
[A chart provided by NASA of the star field that Kepler is examining, in the Cygnus-Lyra region of the milky way. This area is dense with stars. The split squares represent the telescope’s sensors]
The telescope is so sensitive that it can detect the tiny drop in a star’s light when a planet comes between it and Kepler. For an Earth-size planet, that could be a decrease of only 0.01 percent of a star’s already feeble light.
Several transits of the star are needed to prove the presence of a planet. The Kepler team has verified 15 exoplanets in the past.
Nearly as exciting as the discovery of possible planets the size of our own pipsqueak is that 54 planet-candidates of all sizes are in their stars’ habitable zones. “Some candidates could even have moons with liquid water,” said William Borucki, the Kepler project’s science principal investigator.
Quoted in a NASA press release, he added, “Five of the planetary candidates are both Earth-size and orbit in the habitable zone of their parent stars.”
So far Kepler has noted 1,235 potential planets. Most of them, Borucki said, “I’m convinced, will be confirmed as planets in the coming months and years.”
[A by NASA illustration of candidate planets found by Kepler within its small study region. It shows Earth-size planets scattered throughout the field]
Kepler’s candidates include, in addition to the 68 Earth-size planets, 288 super-Earth-size, up to twice our planet’s mass; 662 the size of Neptune; 165 the size of Jupiter, the largest planet in the solar system, and 19 that are larger than Jupiter.
In the habitable zone, five are close to the size of Earth, with the 49 others varying from super-Earth-size to larger than Jupiter.
Additionally, 170 of the candidates show evidence of being in multiple-planet star systems, according to NASA. The system dubbed Kepler 11, about 2,000 light-years away, apparently has at least six planets. They are tightly bunched, all of them closer to their star than Venus is to the sun; five of them have orbits that are smaller than Mercury’s, the closest to the sun.
The release quotes Borucki: “The fact that we’ve found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting stars like our sun in our galaxy.”
After all, the telescope can only find planets that orbit in a direction that happens to bring them in front of the star from our perspective. Because only a small proportion of the sky is part of the survey, and because only a relatively few planets would cross their stars from our viewpoint, he said, “our results indicate there must be millions of planet orbiting the stars that surround our sun.”
Patrick Wiggins, a NASA solar system ambassador to Utah, was having dinner Wednesday night in the Denny’s Restaurant in Tooele, when “a very elderly, white-haired lady approached.” Having recognized him as one of Utah’s best-known astronomers, she asked him about the new planets.
“Who says there’s no interest in astronomy?” Wiggins told Nightly News.
To him, the results are great and exciting, but not unexpected.
“I’ve always figured that the eventual discovery of Earth-sized planets was something of a given,” he said. Now he is anticipating the discovery of planets that are confirmed to be Earth-like —- that is, actually habitable.
“Today’s announcement was one more important step along that journey.”
“In one generation we have gone from extraterrestrial planets being a mainstay of science fiction, to the present, where Kepler has helped turn science fiction into today’s reality,” a NASA release quotes Charles Bolden, administrator of the agency.
Jay Eads, a Kearns teacher, amateur astronomer and astronomy blogger, said the ramifications would apply not only to our own galaxy but to the great Andromeda Galaxy “and all the other spiral galaxies that are out there (we’ll bypass the elliptical galaxies for now). …
“To assume we are alone in the universe is something I can no longer agree with. I find it far more likely that there is intelligent life out there in the universe, than there is not. Doesn’t mean we get to meet them, but I’m sure they are out there.”
Eads concluded, “It’s an exciting time to be alive.”