Kepler-452b: Four reasons to get excited about Earth 2.0, and four reasons you’re still going to die on Earth 1.0

When NASA uses the phrase “Earth 2.0” in a press conference, you know people are going to get very excited indeed. Scientists have been looking for a planet with Earth-style properties for decades, and Kepler-452b seems to fit the bill. It’s almost the dictionary definition of exciting news. 

That said, it’s easy to get carried away with this kind of announcement. So, I’m going to build you up a bit first, and then pour a smidgen of cold water on that excitement. Sound fun? Good, strap in.

Let’s get excited:

1) It could be near-identical to Earth

After NASA’s briefing yesterday, it’s apparent that Earth and Kepler-452b have a surprising amount in common. Kepler-452b also orbits a G2-type star, is likely to have a cloud-based atmosphere, has a good chance of being a rocky planet, and has a year that lasts 385 days – only 5% longer than an Earth year. That isn’t even a full month’s difference.

2) It’s in its own “Goldilocks zone”

So far, so Earth-like. However, even more exciting is that it falls within a habitable zone of planets, meaning it’s too cold for water to evaporate and warm enough to stop it freezing. Water is essential for all forms of life.

It could, therefore, be a Goldilocks planet – not too hot or cold, but just right. If it’s good enough for Goldilocks, it might be good enough for humans.

3) It has 1.5 billion years on us

Our sun is around 4.5 billion years old. We can all agree that’s pretty old, but it’s nothing on Kepler-452b’s parent star, Kepler-452. It’s six billion years old and has a similar temperature to our sun, despite being 10% larger and 20% brighter.

Why is this exciting? Well, life on Earth is estimated to have begun 3.5 billion years ago, and humans didn’t appear until 200,000 years ago. That’s right, Kepler-452b has an extra 1.5 billion years for life to have potentially evolved.

All of these points mean…

4) It stands a chance of having life on it. OMG.

Gsdsadasdomg…!

Given I seem to have lost the ability to type in all this excitement, I’ll let Kepler’s lead data analyst John Jenkins fill in the gaps: “It’s awe-inspiring to consider that this planet has spent six billion years in the habitable zone of its star; longer than Earth. That’s substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet.”

You’ve now reached peak excitement and are in no state to go back to what you were doing before.

Let me calm you down a bit.

1) We have no way of getting there

Kepler-452b is really, really far away – 1,400 light years, to be precise. That’s 8,230,075,757,747,774 miles. It would take New Horizons around 25.8 million years to get there and our strongest telescopes can’t even see it.

But how do we know so much about something invisible? The Kepler spacecraft sees 452b’s weak shadow when it passes its star, leaving the NASA data scientists fill in the gaps. Naturally, a lot of this is guesswork, meaning…

2) We don’t know for sure if there’s water

Again, what we know about Kepler-452b is patchy at the moment, given that we can’t even see it. Even if the conditions are right for water to be there, we don’t know for sure that it is. It’s why all the news reports about the planet contain caveats like “could” and “might”.

Life as we know it can’t exist without water.

3) Even if there was water once, there might not be anymore

Given Kepler-452b’s “sun” is 1.5 billion years older than Earth’s, it’s possible that if it had water on it once, it might not still be there.

As Dr Doug Caldwell, a SETI Institute scientist, explained: “If Kepler-452b is indeed a rocky planet, its location vis-a-vis its star could mean that it is just entering a runaway greenhouse phase of its climate history.”

“The increasing energy from its ageing sun might be heating the surface and evaporating any oceans. The water vapour would be lost from the planet forever.”

4) We’re a few years from knowing anything for sure

The Hubble telescope can’t see Kepler-452b. It’s just too far away.

But there’s a successor on the way – the James Webb telescope. It is 100 times more powerful than Hubble, and will be used by NASA for atmospheric analysis. However, it’s not due to launch until October 2018, so any hopes of getting more insight before then are slim.

Despite this, there’s a reason why NASA’s press release is filled with excitement. This is a huge development: we’re just some way from knowing exactly how huge, given the amount of guesswork involved. Roll on 2018.