The Search for Life: Earth-Size Planet, in the Habitable Zone — Found

Many of this galaxy's 17,000,000,000 or so roughly Earth-size planets are probably too hot or too cold to support life. Last week, scientists found one that is a little cooler than our home: but not by much.

1. Right Size, Right Temperature: Kepler-186f Might Support Life
   • Known Planets: 1,800 Confirmed as of This Month; One Resembles Earth
2. NASA's Kepler Mission and Habitable Zones
   • Kepler-186f: Summary and Slide Show Excerpts

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Democritus Vindicated: After 2,000 Years

(From NASA, ESA, STScI/AURA, used w/o permission.)
(Part of the Eagle Nebula, where gas and dust from long-dead stars collapse, forming a new generation.)

Two dozen centuries back, Democritus thought that many worlds exist, that each had a beginning, and that each would eventually end. These radical ideas didn't sit well with folks like Plato: but it looks like Democritus was right.

Aristotle was in his teens when Democritus died, and noticed details about cephalopods that most folks didn't believe until 19th century scientists confirmed his observations. He was a very smart man.

However, Aristotle thought that Earth was the center of the universe: and that the universe was eternal. Just about all educated westerners agreed, until about five centuries ago.

That's when several natural philosophers in Europe noticed that motions of Venus, Jupiter, Mars, Saturn, and Mercury, make more sense in models that place them, and Earth, orbiting the sun. One of them, Galileo Galilei, even observed objects circling Jupiter. I'll get back to Aristotle, Galileo, and getting a grip.

We sent robots to other planets in the Solar system in the last decades of the 20th century: but still hadn't observed any circling other stars. Then, in 1995, Michel Mayor and Didier Queloz announced that they'd detected a planet orbiting 51 Pegasi. Other astronomers confirmed 51 Pegasi b's existence.

Earth-Like Planet Found: After 20 Years

For the first time, we knew that at least one planet orbits a star other than ours. Scientists developed increasingly precise instruments and methods for detecting extrasolar planets and discovered dozens of worlds: then hundreds; with more emerging as fast as the data gets processed.

So far, we've confirmed more than 1,800. The Extrasolar Planets Encyclopedia added another 702 'possibles' last month. We're reasonably sure that we'll eventually find billions of roughly Earth-size planets in this galaxy. (April 18, 2014)

Last week, we spotted an Earth-sized planet orbiting its star every 130 days. 'Sunlight' at high noon would be about as bright and hot as sunlight here an hour before sunset: but if Kepler-186f has an atmosphere and water, some of that water will almost certainly be liquid.

I'm not surprised that we found a planet which is very nearly Earth's twin: but I'm impressed that we found one so soon after spotting 51 Pegasi b.

Maybe we just 'got lucky,' or maybe we found one so soon because many of the billions of Earth-size worlds are in their stars' habitable zones.

The Quest for Life: and Neighbors

(From ESO/L. Calçada, via Wikimedia Commons, used w/o permission.)

If we discover life on other planets while I'm still around, I'll be delighted.

From the way folks respond to new ideas, I'm pretty sure that many will share my fascination.

Others, apparently convinced that God wouldn't or couldn't disregard their values and assumptions, will almost certainly denounce reports of extraterrestrial life as a Satanic plot. We've gone through this sort of goofiness with vaccinations and evolution. (February 12, 2014; January 2, 2014)

I hope we find neighbors in the universe: people who aren't human, but share our nature: creatures with intelligence and will, made of spirit and matter. (Catechism of the Catholic Church, 311, 362-368)

I think it's very likely that life started on other worlds. Given the size and age of the universe, I'd be surprised if we don't eventually run into people whose ancestors weren't at all like ours. On the other hand, we may be alone in the universe.

At this point, we don't know: and I certainly won't claim that God couldn't have created life throughout the universe.

That'd be as daft as saying that other worlds can't exist, because Aristotle said so. That's been against the rules for Cathoics since 1277, by the way. (February 23, 2014)

Aristotle, Galileo, and Getting a Grip — or — Poetry Isn't Science

(From Roberto Pillon, via Wikimedia Commons, used w/o permission.)
(Aristotle observed and described electric rays like this one.)

Ancient Greeks were top-rate at discussing ideas: but not so renown for verifying their theories with observation. They weren't pure theorists, though. One of them, Aristotle, carefully observed catish, cephalopods and ruminants.

Aristotle was brilliant, and helped lay the foundations of today's science. Two millennia later, many European scholars made the mistake of assuming that every Aristotelian assertion was accurate.

Disagreeing with Aristotle, agreeing with St. Augustine that poetry isn't science, and insisting that his theory be accepted as fact, got Galileo in trouble.

That doesn't show that religion is against science, any more than charges of heresy leveled against Dante proves that Christianity opposes poetry.¹

It does, I think, show emotion and reason don't play well together, and that's another topic. (December 8, 2013; Another War-on-Terror Blog, December 23, 2008)

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1. Right Size, Right Temperature: Kepler-186f Might Support Life

(From NASA/JPL-Caltech, used w/o permission.)
"Kepler-186f, the first validated Earth-size planet to orbit a distant star in the habitable zone, a range of distance from a star where liquid water might pool on the planet's surface, is seen in a NASA artist's concept released April 17, 2014."

"Scientists find Earth-sized world in orbit friendly to life"
Irene Klotz, Reuters (April 17, 2014)

"For the first time, scientists have found an Earth-sized world orbiting in a life-friendly zone around a distant star.

"The discovery, announced on Thursday [April 17, 2014], is the closest scientists have come so far to finding a true Earth twin. The star, known as Kepler-186 and located about 500 light years away in the constellation Cygnus, is smaller and redder than the sun.

"The star's outermost planet, designated Kepler-186f, receives about one-third the radiation from its parent star as Earth gets from the sun, meaning that high noon on this world would be roughly akin to Earth an hour before sunset, said astronomer Thomas Barclay, with NASA's Ames Research Center in Moffett Field, California.

"The planet is the right distance from its host star for water -- if any exists -- to be liquid on the surface, a condition that scientists suspect is necessary for life.

" 'This planet is an Earth cousin, not an Earth twin,' said Barclay, who is among a team of scientists reporting on the discovery in the journal Science this week....

"...'This planet is in the habitable zone, but that's doesn't mean it is habitable,' Barclay said...."

The artist's concept of what Kepler-186f's appearance makes optimistic assumptions: that the planet has an atmosphere like Earth's, and enough water to "pool" on the surface. Right now, we don't know what Kepler-186f is made of, or if it has an atmosphere of any sort.

It could be an airless ball of rock, be shrouded in an atmosphere as thick and toxic as we found around Venus: or it could be a slightly-cooler version of Earth, complete with folks who started building cities when dinosaurs still lived.

We don't know. Yet.

Known Planets: 1,800 Confirmed as of This Month; One Resembles Earth

"So far, scientists have found nearly 1,800 planets beyond the solar system.

" 'The past year has seen a lot of progress in the search for Earth-like planets. Kepler-168f is significant because it is the first exoplanet that is the same temperature and is (almost) the same size as Earth,' astronomer David Charbonneau, with the Harvard-Smithsonian Center for Astrophysics, wrote in an email.

" 'For me the impact is to prove that yes, such planets really do exist,' Charbonneau said. 'Now we can point to a star and say, "There lies an Earth-like planet." ' "
(Irene Klotz, Reuters)

As David Charbonneau said, no matter what we learn about Kepler-186f, its existence proves "that yes, such planets really do exist ... There lies an Earth-like planet."

I think it's wildly improbable that Earth and Kepler-186f are the only two planets that are Earth-like. Particularly since we spotted this one less than 20 years after the first discovery of an extrasolar planet.

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2. NASA's Kepler Mission and Habitable Zones

(From NASA Ames/SETI Institute/JPL-Caltech, used w/o permission.)
"The diagram compares the planets of our inner solar system to Kepler-186, a five-planet star system about 500 light-years from Earth in the constellation Cygnus. The five planets of Kepler-186 orbit an M dwarf, a star that is is half the size and mass of the sun."

"NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star"
NASA (April 17, 2014)

"Using NASA's Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the "habitable zone" -- the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.

"While planets have previously been found in the habitable zone, they are all at least 40 percent larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth.

" 'The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth,' said Paul Hertz, NASA's Astrophysics Division director at the agency's headquarters in Washington. 'Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds.'..."

I'm excited by the discovery of a planet that's so close to being Earth's twin in terms of size and temperature. If we find life elsewhere, it may be on a world very similar to our home: or not.

Kepler-186f: Summary and Slide Show Excerpts

These two images are from a NASA Presentation, introducing what we know about Kepler-186f: and what we don't.


(From NASA, used w/o permission)


(From NASA, used w/o permission)

Kepler-186f's orbit is considerably smaller than Earths. It may be a trifle cooler than Earth because Kepler-186 is smaller and cooler than our star.


(From NASA, used w/o permission)

Background:

• Other worlds
  • Presentation: Kepler-186f
    Douglas Hudgins, NASA Headquarters; Elisa Quintana, SETI Institute at NASA Ames; Tom Barclay, Bay Area Environmental Research Institute at NASA Ames; Victoria Meadows, University of Washington, Virtual Planetary Laboratory Lead Team, NASA Astrobiology Institute
    (From www.nasa.gov/ames/kepler/digital-press-kit-kepler-186f-an-earth-size-habitable-zone-planet/ (April 21, 2014))
  • "Scientific Quest Into Evolution of Life in the Universe"
    Govind Swarup, Scientific Insights into the Evolution of the Universe and of Life, Pontifical Academy of Sciences, Acta 20, (2009)
    (From http://www.casinapioiv.va/content/dam/accademia/pdf/acta20/acta20-swarup.pdf (April 23, 2014))
  • "The Discovery of Extrasolar Planets"
    Pierre Léna, Paths of Discovery, Pontifical Academy of Sciences, Acta 18, (2006)
    (From http://www.casinapioiv.va/content/dam/accademia/pdf/acta18/acta18-lena.pdf (April 23, 2014))
• Getting There
  • "Warp Field Mechanics 101"
    Dr. Harold "Sonny" White, NASA Johnson Space Center (2011)
    (from http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023492_2011024705.pdf (March 18, 2013))
  • "Eagleworks Laboratories: Advanced Propulsion Physics Research"
    Dr. Harold "Sonny" White, Paul March, Nehemiah Williams, William O’Neill; NASA Johnson Space Center (2011)
    (from http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015936_2011016932.pdf (March 18, 2013))
  • How to Build an Antimatter Rocket for Interstellar Missions
    Systems Level Considerations in Designing Advanced Propulsion Technology Vehicles
    Robert H. Frisbee, Jet Propulsion Laboratory, California Institute of Technology (2011)
    (From http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38278/1/03-1942.pdf (January 11, 2011))

Related posts:

• Life
  • "Life in the Universe: Focusing the Search"
    (April 18, 2014)
    Particularly
    • Earth-Sized Planets: Billions of Them
  • "Kepler-69c and Habitable Zones; The Great Martian Land Rush"
    (October 25, 2013)
    Particularly
    • Habitable Zones and Kepler-69c: There's More to Learn
  • "Oxygen, Life, and Autocells"
    (October 18, 2013)
  • "Life in the Universe, God, and Getting a Grip"
    (October 17, 2013)
  • "Earth May Not Be a 'Class M' Planet"
    Apathetic Lemming of the North (December 5, 2009)
• Neighbors
  • "Strange New Worlds; Getting a Grip about Space Aliens; and a Fossil Fish"
    (January 17, 2014)
    Particularly
    • Little Green Men and the Almighty Buck
    • Rungs on the Ladder of Creation
  • "Time, the Universe, and Space Aliens"
    Apathetic Lemming of the North (April 20, 2012)
  • "Science isn't a Four-Letter Word"
    (January 29, 2012)
    Particularly
    • Science, Religion, and (fictional) Christians"
  • "Gliese 581g, Space Aliens, and the Canals of Mars"
    Apathetic Lemming of the North (October 12, 2010)
    Particularly
    • Space Aliens May Not be Human"
  • " 'All We Want is Peace and Quiet' - Another Look at the Mind of the Alien"
    Drifting at the Edge of Time and Space (December 9, 2009)
• Technology
  • "Fusion Power, Terraforming, and Old Dutch Windmills"
    (October 11, 2013)
  • "Warp Drive: Imagined and Real (Maybe, Eventually)"
    (May 24, 2013)
    Particularly
    • Travel to the Stars
    • Science, Technology, and Doing Our Job
    • Weird Physics, Warp Drive, News, and NASA
  • "Warp Drive: Silly as Thinking People can Fly"
    Apathetic Lemming of the North (May 17, 2013)
  • "Another Step Closer to a Practical Warp Drive: Maybe"
    Apathetic Lemming of the North (November 30, 2012)
  • "Antimatter Rocket Motor: Physics, Straightforward; Engineering, Not So Much"
    Apathetic Lemming of the North (October 26, 2012)

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¹An "absurd charge" of heresy, brought by "those to whom the language of poetic imagery is a sealed book:"

" 'here shall they hang:' Nowhere, perhaps, does Dante assert more clearly than in this moving an terrible image his conviction of the intimate and unbreakable bond between spirit and flesh. The Suicides willed the death of the flesh, but they cannot be rid of it: their eternity is an eternity of that death. (The absurd charge of heretically denying the resurrection of the body was brought against Dante on the strength of these lines, but only by those to whom the language of poetic imagery is a sealed book.)"
(Dorothy L. Sayers' footnote to "The Divine Comedy," Inferno, Canto XIII, line 107; "The Divine Comedy 1 Hell," Dante Alighieri, Translation by Dorothy L. Sayers (1949); Penguin Classics reprint)