Venus and Mars are the most like Earth, but in different ways. In terms of size, average density, mass, and surface gravity, Venus is very similar to Earth. But Mars is the planet that is most similar to Earth in other ways.
Known as Kepler 452b, the world is estimated to be a bit on the hefty side, at five times the mass of Earth, but it is receiving just 10% more heat and light than we do from its G-type star, just like our sun but 1.5 billion years older.
To date, scientists have discovered 55 planets that could be Earth-like. In comparison to the over 4,000 known planets, 55 seems small.
'Pale blue dot' planets like Earth may make up only 1% of potentially habitable worlds.
Proxima Centauri is 4.2 light-years from Earth, a distance that would take about 6,300 years to travel using current technology. Such a trip would take many generations.
Most astronomers feel that it would be impossible for life to exist on Venus. Today, Venus is a very hostile place. It is a very dry planet with no evidence of water, its surface temperature is hot enough to melt lead, and its atmosphere is so thick that the air pressure on its surface is over 90 times that on Earth.
And similar to how the Earth has the sun, Kepler-452b orbits around Kepler-452, a star 6 billion years old, which is pretty old in comparison to the solar system's sun, aged 4.5 billion years. But Kepler-452 has around the same temperature as the sun, which can support the idea that Kepler-452b can still harbor life.
So 1,400 light-years equals about 8.2 quadrillion miles. If we took one of our fastest probes to the planet, New Horizons, which is currently traveling about 36,000 miles per hour (50,000 km/h), it would take well over 26 million years to reach our destination.
Astronomers think such a planet, called an Earth 2.0, would have the right conditions for liquid water — and possibly life — to exist. More than 5,000 exoplanets have already been discovered in the Milky Way, mostly with NASA's Kepler telescope, which was in use for 9 years before it ran out of fuel in 2018.
Additionally, Titan's rivers, lakes and seas of liquid methane and ethane might serve as a habitable environment on the moon's surface, though any life there would likely be very different from Earth's life.
Potential for Life
The surface of Pluto is extremely cold, so it seems unlikely that life could exist there. At such cold temperatures, water, which is vital for life as we know it, is essentially rock-like. Pluto's interior is warmer, however, and some think there could even be an ocean deep inside.
Potential for Life
Uranus' environment is not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme and volatile for organisms to adapt to.
Despite its smaller size, the planet's land area is also roughly equivalent to the surface area of Earth's continents—meaning that, at least in theory, Mars has the same amount of habitable real estate. Unfortunately, the planet is now wrapped in a thin carbon dioxide atmosphere and cannot support earthly life-forms.
Light-year is the distance light travels in one year. Light zips through interstellar space at 186,000 miles (300,000 kilometers) per second and 5.88 trillion miles (9.46 trillion kilometers) per year.
In about 40,000 years, Voyager 1 will drift within 1.6 light-years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis which is heading toward the constellation Ophiuchus.
So will it ever be possible for us to travel at light speed? Based on our current understanding of physics and the limits of the natural world, the answer, sadly, is no.
At the current rate of solar brightening—just over 1% every 100 million years—Earth would suffer this "runaway greenhouse" in 600 million to 700 million years. Earth will suffer some preliminary effects leading up to that, too.
It is unlikely that life as we know it could survive on Mercury due to solar radiation, and extreme temperatures.
Surface. As a gas giant, Jupiter doesn't have a true surface. The planet is mostly swirling gases and liquids. While a spacecraft would have nowhere to land on Jupiter, it wouldn't be able to fly through unscathed either.
Perhaps someday, after Saturn's rings have dissipated, the universe might give the planet a new set. “Maybe through some process—another moon is broken apart, a comet comes in too close—and you start it all over again,” Spilker said.
Jupiter is made of mostly hydrogen and helium gas. If you tried to land on Jupiter, it would be a bad idea. You'd face extremely hot temperatures and you'd free-float in mid-Jupiter with no way of escaping.
In the Solar System's habitable zone, there are only three natural satellites—the Moon, and Mars's moons Phobos and Deimos (although some estimates show Mars and its moons to be slightly outside the habitable zone) —none of which sustain an atmosphere or water in liquid form.
Saturn's moon Enceladus could be habitable, according to a study published last Monday. In the search for extraterrestrial life, a group of scientists discovered new evidence that the subsurface water ocean of Enceladus contains the building blocks of life.