Is there anybody out there? Astronomers and dreamers have been asking this question since the dawn of humanity — and yet, the mystery remains. Are we the only life forms in the universe, or are neighbors like us lurking just beyond the reaches of our solar system? NASA has made it a mission to discover the truth. In March 2009, the space agency launched the Kepler Mission, a NASA Discovery program designed to look for possible life-supporting planets. In just the first 16 months of operation, Kepler has discovered 2,326 potential planets. Once confirmed by follow-up studies, these potential discoveries could significantly raise the tally of exoplanets (planets outside our solar system) well over its current count of 702. Here are 10 images from NASA depicting these wild worlds.
Pictured here is an artist’s depiction of Kepler-22, which was the first exoplanet discovered by Kepler to orbit in a star’s habitable zone. This means that Kepler-22 may have liquid water on it like Earth, making it our closest possible sister planet. As NASA writes, “the planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habitable zone of a star like our sun.”
Why are we looking for exoplanets such as Kepler-22? Experts say the future of humanity may depend on it. Finding a planet that can sustain life may be the key to the survival of our people, as our planet could fall victim to an asteroid, solar flare, or our own obtuse treatment of it. However, not all planets NASA has discovered are livable. This is an artist’s depiction of Kepler-16b, the most “Tatooine-like” planet yet found. NASA refers to its two suns, which resemble Luke Skywalker’s home planet in “Star Wars.” Even though it circles two stars, the planet is thought to be extremely cold and have a gaseous surface.
Given the vastness of our galaxy, you would think the Kepler spacecraft would be sweeping every inch of the skies. However, due to mission constraints, Kepler is focused on one large area that includes the constellations Cygnus and Lyra. Here, we see this region. “Each rectangle indicates the specific region of the sky covered by each CCD (charged coupled devices) element of the Kepler photometer,” according to NASA. The Earth makes it difficult to observe all parts of the sky all year round, so the Kepler spacecraft is positioned above the ecliptic plane. Kepler can watch 100,000 stars simultaneously. The Cygnus and Lyra region was chosen because of its abundance of stars similar to our sun. The end goal? That we will find planets like Earth.
Kepler is not the only space instrument trained on exoplanets. Here is an artist’s view of the hot gas planet, HD 209458b, as depicted from information obtained by the Hubble and Spitzer space telescopes. The two instruments revealed that there are molecules of methane, water vapor and carbon dioxide in the planet's atmosphere. HD 209458b orbits a sun-like star 150 light-years away in the constellation Pegasus in a 3.5-day orbit. This planet is not habitable, but experts say that the presence of life-bearing molecules could indicate life on similar planets, but with a rocky surface.
Ever wonder what happens to our solar system after the sun runs its course in 5 or so billion years? Here we see an artist’s conception of a pulsar planet system. A pulsar is a rapidly rotating neutron star that holds the collapsed core of a dead star. In 1992, astronomer Aleksander Wolszczan discovered this pulsar, which is namedPSR B1257+12. Here we see at least two Earth-like sized planets rotating it. Radiation from the pulsar is likely “raining” down on the planets, causing magnificent auroras all through their atmospheres. These planets may be part of asecond generation of planets that formed after the deadening blast of the dying star.
2011 was a a “banner year” for the Kepler Mission with the discovery of thousands of potential exoplanets. Early in 2011, NASA announced the discovery of Kepler 10b, the smallest planet yet found and by far the rockiest. While Kepler 10b was too hot to support life, it showed that the Kepler Mission was capable of finding planets closer to the grand prize — one that could sustain life as Earth does. This photo is an artist’s depiction of the molten cliffs of Kepler 10b, which is thought to sustain temperatures up to 2,500 degrees Fahrenheit. This means that the surface of Kepler 10b is hotter than any lava flow on Earth — and hot enough to melt iron.
This is an external view of Kepler 10b as depicted by a NASA artist. The planet simmers in this image, likely because it is orbiting its star as much as 20 times closer than Mercury orbits our sun. How has NASA discovered planets such as Kepler 10b? Kepler operates by scanning the brightnessof more than 100,000 stars every 30 minutes. The brightness is measured by a photometer, or light meter, which is aboard the Kepler spacecraft. It looks for “tiny winks” or variations in the star’s brightness that occur when an exoplanet passes in front of it.
Kepler 10b, in all its fiery glory, is not the hottest exoplanet we've discovered. Depicted here is an artist’s depiction of HD 149026b, a “hot Jupiter” that clocks in at a scorching 3,700 degrees Fahrenheit, making it three times hotter than our hottest planet, Venus. How hot is it? “The planet is so warm that astronomers believe it is absorbing almost all of the heat from its star, and reflecting very little to no light,” says NASA. This almost makes this planet the blackest, or darkest planet in the known universe. The planet, which was observed by the Spitzer Space Telescope, is believed to be much cooler on its dark side. Because the planet appears to be “tidally locked” to its sun — just as our moon is locked to the Earth — one spot on the planet is under constant heat.
Does a planet have to be just like Earth to support life? NASA isn’t sure. Here we see an artist’s conception of a planet around a star that is cooler than our sun — these are called M-dwarfs and brown dwarfs. It is still unclear if cooler stars can support young planets with the same life-forming chemical mix that began life on Earth. For a planet to sustain life, it must be able to carry water below boiling point yet above freezing. In addition, it must have enough air — but not too much. This delicate balance depends on the proximity of the star to the planet.
Pictured here is an artist’s depiction of a two-star system called HD 113766, where NASA believes a rocky, Earth-like planet is forming some 424 light-years away. The brown, rocky ring of material in the image depicts an early planet before it binds together to form a more spherical shape. This star is thought to be 10 to 16 million years old, the right age for planets to come into formation.
But could this be a planet that supports life? As the quest for an Earth-like planet continues, experts are optimistic. Natalie Batalha is Kepler's deputy science team lead. As she told Space.com,via MNN, "We are homing in on the truly Earth-size, habitable planets."
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