Earth may not be the only habitable world within the Milky Way galaxy.
According to newly published report, many Earth-like planets exist within the Milky Way and at least a handful may exist within our own cosmic backyard.
The study, published by researchers at the Harvard-Smithsonian Center for Astrophysics, finds that upwards of 4.5 billion Earth-like planets may reside in the Milky Way, possibly providing astronomers with a chance to capture more accurate data on planets similar to our own.
“Now that we know there are going to be Earth-like planets nearby, we don’t have to look so far away,” said Harvard astronomer David Charbonneau, a co-author of the study.
While the study does not explicitly point to recently discovered planets nearby, author of the study, Courtney Dressing, told SPACE.com that ”according to our analysis, the closest Earth-like planet is likely within 13 light-years, which is right next door in terms of astronomical distances.”
The study, based on data collected by NASA’s Kepler Space Telescope, is the latest attempt to calculate the number of planets in the galaxy. So far, since the telescope’s 2009 debut, Kepler has detected 2,740 possibly Earth-like planets. While scientists have only confirmed 105 of those planets detected, they estimate that over 90 percent of the possible planets will also be confirmed upon further analysis.
The study’s estimates are largely based on a new modeling theory for counting the number of Earth like planets. The latest study relies on the number of red dwarf stars residing the galaxy. Approximately six percent of the red dwarfs, the most common kind of star, in the Milky Way are suspected to have Earth-like planets orbiting around them. These planets, if they are indeed similar to the Earth, would inhabit the so-called Goldilocks zone of their solar system — the area where temperatures and mass are not too extreme for organisms to emerge and thrive.
Earth’s oldest living creatures may have some interplanetary rivals inhabiting planets in orbit around red dwarfs of the Milky Way. The possibility of ancient life on other planets–much older than the oldest of on Earth–adds to this exciting discovery. These alien Earths have been around much longer than our Earth: since red dwarfs have a significantly longer life span than less common stars like the sun, if living organisms do inhabit the planets within the “habitable zones” around those red dwarfs, its likely life appeared much earlier than the earliest life appeared on Earth.
While Earth is approximately 3.8 billion years old, these alien Earths could be over twice as old, say scientists.
That said, speaking to reporters on Wednesday, the pair of astronomers played down expectations. While red dwarfs likely host planets similarly sized to Earth with the ability to hold liquid water – two factors thought essential for a planet to harbor life — the planets are likely to be very different from Earth in many ways. The planets, which are “tucked close” to their respective star, may be bathed in radiation or are tidally locked to their star, resulting in a range of extreme temperatures.
The study is slated for publishing in the upcoming issue of The Astrophysical Journal