Earth is not necessarily the most hospitable planet in the universe to sustain life, according to new study.
Researchers have found about 24 planets that are "habitable", offering more suitable conditions for life than exist here on Earth.
In fact, some of these planets have even better stars than our Sun, the researchers said.
The new study looked for worlds that would be better at maintaining life on our planet - including those that are older, larger and warmer than Earth - in hopes of helping in future quests for life elsewhere in the universe.
The study identified 24 of the "habitable" planets. They are all 100 light-years away, making it very difficult, if not impossible, to ever see them up close, but research with telescopes of the future could give us much more information about these worlds.
With the technological developments in the coming telescopy Such as its James Webb Space Telescope NASA, the European Space Agency's LUVIOR space observatory and PLATO - researchers hope to be able to detect even traces of life on distant planets.
"With the next space telescopes, we will receive more information, so it is important to choose specific targets," said Dirk Schulze-Makuch, a professor at Washington State University and the Technical University of Berlin, who led the study.
"We have to focus on some planets that have the most promising conditions to sustain life. However, we must be careful not to get stuck looking for a second Earth, because there are probably planets that could be more suitable for life than ours.
The researchers set a number of criteria for such habitable planets. They then explored the 4.500 known planets outside our solar system in an effort to find out who could meet these important criteria.
This included searching for "Dwarf K type" planets that are not like him helium us. What looks like our star - known as the "G type" - has a relatively short lifespan, and since our Sun was almost middle-aged before any complex life was created, many other similar planetary systems could disappear before being inhabited.
The stars K-type dwarfs, on the other hand, are cooler, smaller and brighter than our sun. They have a much longer lifespan - up to 70 billion years - which means that the planets around them will have much more time to develop life.
The researchers also looked at planets that are about 10% larger than Earth, with the idea that they may have a larger habitable zone. More mass would also mean that they would retain more of their core heat, and stronger gravity to keep their atmosphere stable.
The habitable planets will probably have a little more water than the Earth, especially if it is maintained in the form of moisture. Also the hottest climate would make a planet more habitable, with an ideal point of increasing 5 degrees Celsius compared to Earth.
None of the 24 planets described in the study meet all the criteria set by the researchers, despite their huge numbers. One of them met four of these criteria, which means that in theory it would be much more accessible in creating and maintaining life and therefore more likely to be inhabited.
"Sometimes it is difficult to transmit this theory of habitable planets because we believe we live on the best planet," said Professor Schulze-Makuch. "We have a large number of complex and different life forms, and many of them can survive in extreme environments. Earth is certainly a hospitable host for life, but it is probably not the best. "