NASA has discovered 5,005 planets or exoplanets outside of our solar system. But as per NASA’s Exoplanet Exploration Page, more than 4,000 exoplanets have been discovered and are considered "confirmed, since the first such world was confirmed orbiting a sunlike star in 1995. However, Earth is the only one that appears to have the right living conditions for humans. Most of the planets are in a very small region means within thousands of light-years, outside of our galaxy, the Milky Way. It is pertinent to mention that one light-year is 5.88 trillion miles. The closest known exoplanet to Earth, Proxima Centauri b, is about four light- years away.

The first exoplanets were just discovered about two decades ago in the early 1990s, and the number of known exoplanets has doubled approximately every 27 months. NASA has been studying exoplanets for 30 years. As we see on Earth, life can adapt to conditions that human beings would consider very harsh," such as temperature, radiation, salinity, acidity, and aridity. It may be possible that life has started on other worlds and adapted to conditions quite alien to what we are used to, NASA says.

Further NASA officials say that as these planets are extremely far from Earth and there would be an enormous distance to travel so for a person to visit to an exoplanet isn’t looking possible to execute anytime soon. However, NASA suggested a robot could visit an exoplanet like the rovers on Mars one day very far in the future. "Today, NASA is concentrating on the steps to get humans to Mars, which is our next-door neighbour," NASA says.

Among these planets, NASA's Jet Propulsion Laboratory and the University of New Mexico have discovered a new planet TOI-1231b which is three times as big as Earth and 90 light- years away from Earth. The planet, a temperate sub-Neptune-sized body with a 24-day orbit with a temperature/atmosphere of approximately 330 Kelvin or 56.85 degrees Celsius, is quite similar to our Earth. Planet orbiting an M dwarf star also known as a red dwarf. The Nasa scientists anticipated that there might be clouds present high in the atmosphere. The planet might also have evidence of water. It could have large hydrogen or hydrogen-helium atmosphere, or a denser water vapour atmosphere, they said. In the end, we can say that the planet is one step closer to being somewhat like Earth.