What if we discovered earth 2.0?

Could there be a better planet than Earth for us? Scientists are on the hunt for a “super habitable” world—one that wouldn’t just rival Earth but be even more conducive to life. They’re searching for exoplanets. But how would we find Earth 2.0? What makes an exoplanet habitable, and how long would it take to get there? This is What If, and here’s what would happen if we discovered Earth 2.0.

You wouldn’t be able to find an exoplanet just by looking through a telescope. All you’d see is the bright light of the stars it orbits. NASA created the Kepler telescope to discover exoplanets, and before it ran out of fuel, it surveyed our region of the Milky Way galaxy. Kepler used the “transit method” to detect planets hundreds of light years away by measuring fluctuations in light from distant stars. When a planet passes in front of its star, it blocks some of the light, making the star appear dimmer. Kepler used this drop in brightness to identify exoplanets. It’s not an easy task, but during its nine years of operation, Kepler confirmed the existence of 436 exoplanets. Could one of them be Earth 2.0?

If you’re a long-time fan of What If, you’ve probably heard this before: Earth is a very unique place. Even if a planet is considered habitable, it doesn’t necessarily mean it’s anything like Earth. A habitable planet is a rocky world located in the “habitable zone,” where water can exist in liquid form on its surface. That’s the basic requirement. Venus and Mars are both technically habitable, but they are nothing like Earth.

Now, let’s focus on three key conditions we’d look for when searching for a planet even better than Earth.

First, the planet would need sunlight. Our Sun has a lifespan of about 10 billion years, and it took 4 billion years for complex life to evolve here. However, K-type dwarf stars, which have lifespans of about 70 billion years, could give life more time to develop and flourish. If we discovered an exoplanet orbiting a K-type star, it could provide a much longer window for life to thrive.

Second, temperature is critical. A planet that’s too hot or too cold would be inhospitable. But if we find a planet just five degrees warmer than Earth, with more water, it could be the perfect environment—an Earth 2.0 covered in lush, biodiverse rainforests.

The third factor is size. A planet’s gravity helps retain its atmosphere, and there’s a direct relationship between a planet’s size and its gravity. A planet that’s about one and a half times the size of Earth could maintain its interior heat and atmosphere for much longer. However, bigger isn’t always better. While Earth-sized exoplanets tend to be rocky, about 50% of planets larger than Earth are gas giants. If an exoplanet is too small, like Mars, it could end up barren.

So, do any exoplanets meet these criteria? I found one that could be a contender for Earth 2.0: Kepler-1649c. This planet is 300 light years away and orbits a red dwarf star. It receives about 75% of the sunlight that Earth does, meaning it might be cooler, and it might not have seasons. A full orbit takes just 19.5 Earth days, so we’d have to adjust to a much faster year. There’s also a chance it could be tidally locked, meaning one side of the planet always faces the sun, while the other side remains in darkness.

Living on a planet orbiting a red dwarf star could also pose risks. Red dwarfs are known to send out massive solar flares that can flood nearby planets with harmful UV radiation, causing huge temperature swings. Still, if Kepler-1649c is deemed a potential Earth 2.0, what comes next?

Well, using our current technology, it would take at least 2,000 years to reach this distant planet. Right now, we only know its size, distance from its star, and the composition of its atmosphere. We could send humans on a multi-generational journey to Earth 2.0, only to discover that it’s more like Neptune 2.0—a gas giant, which is definitely uninhabitable for humans. We need much more information before considering a trip to any potential Earth 2.0.

Currently, NASA is developing a tiny probe capable of traveling at one-fifth the speed of light, which could vastly expand our knowledge of exoplanets. But we shouldn’t limit ourselves to just exoplanets. Moons can also be viable candidates for human habitation. A moon receives direct solar energy from its star, and the planet it orbits can reflect solar energy toward it, making it potentially more suitable for life than an exoplanet.

The most Earth-like body in our solar system is Titan, Saturn’s largest moon. So, if we want to avoid thousands of years of travel, Titan could be a strong contender as a second home for humanity.