You might have heard that NASA just discovered Earth 2.0.
That's right...the US space agency has confirmed that a habitable planet much like our own is orbiting a star that's also much like our own. It's like Earth's doppelganger (hence the 'Earth 2.0' nickname).
Is there life on this planet? How far away is this planet? You probably have so many questions that need answering, but don't worry, because we've managed to answer all of them below.
What is NASA's Kepler mission?
The Kepler Mission is NASA's attempt at surveying our region of the Milky Way galaxy in order to discover Earth-like planets. NASA wants to find terrestrial planets (i.e., those one-half to twice the size of Earth) within habitable zones of their stars (so that liquid water might exist on the surface of those planets).
Terrestrial planets are just one type of exoplanet (which is a planet that orbits a star, stellar remnant, or a brown dwarf). They are Earth-like planets made up of rocks or metals with a hard surface. They also have a molten heavy metal core. In our solar system, there are four: Mercury, Venus, Earth, and Mars.
Kepler is a space observatory launched in 2009, with the purpose of discovering more Earth-like planets orbiting other stars. The spacecraft uses a photometer to continually monitors the brightness of over 145,000 main sequence stars in a fixed field of view, and then it transmits that data to Earth for scientists to analyse.
How many Earth-like planets has Kepler discovered?
The Kepler spacecraft has found 4,696 exoplanet candidates (aka planets orbiting a star, etc).
As of January 2015, the Kepler spacecraft has detected 1,000 confirmed exoplanets in our galaxy, including super-Earths and planets that orbits two stars, but only some of those planets have been confirmed to be less than twice Earth-size and located within habitable zones of their host stars.
That said, in July 2015, NASA's Kepler mission confirmed that it finally discovered the very first near-Earth-size planet within the habitable zone of a Sun-like star. Amazing, right? It's called Kepler-452b.
The confirmation of Kepler-452b brings the total number of exoplanets to 1,028, but the number of exoplanets confirmed to be less than twice Earth-size and located within a habitable zone is now at 11.
What is Earth 2.0?
NASA has announced the discovery of Kepler-452b. It's the smallest planet we've found yet orbiting within a star's habitable zone, meaning it's warm enough to have liquid surface water. And its host star is a G2-type, which is just like our sun. NASA is therefore calling this Earth-like planet "Earth 2.0".
Here are some key facts about Kepler-452b:
- Kepler-452b is about 60 percent larger than Earth and orbits its host star - called Kepler-452 - once every 385 days, which is only 20 days longer than it takes the Earth to orbit the Sun.
- NASA doesn't know Kepler-452b's mass or what it’s made of, but they believe the exoplanet is rocky.
- Kepler-452 is a lot like our Sun in that it is about the same size (10 per cent larger, actually) and temperature, but it's also 20 percent brighter and about 6 billion years old (1.5 billion years older than the Sun).
- Kepler-452b is 5 percent farther from its star than Earth is from the Sun.
- Kepler-452b’s system is 1,400 light years away from our Solar System and is located in the constellation Cygnus.
Does life exist on Kepler-452b?
NASA believes life might be existing on it. “We can think of Kepler-452b as an older, bigger cousin to Earth," said Jon Jenkins, a data analyser who led the team that discovered Kepler-452b, during a NASA press conference.
He continued: "This planet has spent 6 billion years in the habitable zone of its star; longer than Earth. That’s substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet...This is really the first step, and humankind’s first step, to answering that question 'Are we alone in the Universe?'"
Is Kepler-452b unique?
Yes and no.
It's substantial, but keep in mind astronomers at the SETI Institute and NASA Ames Research Center found another Earth-sized exoplanet, called Kepler-186f, orbiting in a star’s habitable zone just last year.
Kepler-452b is unique in that it is orbiting a star much like our own, whereas Kepler-186 has a red dwarf for a host star.