Advanced scientific techniques have resulted in the discovery of thousands of Earth-like Planet that have their own Solar System.
Just a brief twenty five years ago, if you had asked astronomers and astrophysicists whether or not was any Earth-like planet around different stars, the answer would have been, “probably, however we do not understand for sure.“
Now, because of a variety of latest techniques and advanced instrumentation, we’ve currently discovered thousands of stars inside our own galaxy that have their own solar system!
Earth-like planets come in an enormous diversity of sizes and masses, and are found at all kinds of orbital distances. For Example:
- There is a hot Jupiter exoplanet locked in a strange death spiral with its parent Star.
- There are Solar Systems with 5 planets inside to where Mercury is to our Sun!
- There is the largest planet found orbiting 2 Suns (real-life Tatooine?)
There are over two hundred Earth-sized planets discovered around different stars to date, and twenty one rocky worlds within the habitable zones of their stars.
Almost all of this info came from NASA’s Kepler mission, that has been the key exoplanet discovering tool at our disposal.
An Example: In May 2016, we saw the transit of Mercury in front of the Sun. It passed in front of the Sun’s disk, blocking its light for a brief amount of time.
At the beginning such a transit, the host star’s brightness drops by some portion as the star’s disk is covered. Then it will revert back once more once the planet moves off.
That apparent dip within the star’s brightness, as small as it is, provides us with the very technique that Kepler uses to discover planets around stars aside from our own.
So once a planetary system is dead aligned with a star, relative to our line-of-sight, we are able to observe this transit, and discover worlds around that star.
The Kepler spacecraft ascertained a field of view containing close to 150,000 stars over a time of roughly four years. During this time it detected over 2,000 planets and with over 1,000 additional “likely Earth-like planets” that are still awaiting confirmation.
Wait… just 2,000 planets from 150,000 stars! 😥
But don’t feel down yet. This does not mean that only 1%-2% of stars have planets around them.
The problem is that the probability of getting a good planetary alignment with our line-of-sight is extremely low. And moreover, we are able to solely find Earth-like planet with orbital periods that are less than Kepler’s observing time, thus nothing farther out than Mars is.
Perfect Attributes of an Earth-like Planet
When we tend to compare what we have seen with what we expect to be there from the things we cannot yet see, we discover some unimaginable things:
- About 80% of star systems are expected to own planets around them.
- The overwhelming majority of planets are 3 times the size of Earth or smaller, not superior planet worlds or gas giants.
- It’s approximated that there are close to 60 billion rocky, habitable-zone Earth-like planets in our galaxy alone.
But there’s an enormous difference between a potentially habitable Earth-like planet as we tend to define it — a rocky planet at the correct distance from its star that, with Earth-like atmospheric conditions, and having liquid water on its surface — and a planet that is capable of being a home for humans. Inshort, a real Earth-like Planet.
Because what we want is way more specific than that.
Sure, we want a rocky, habitable-zone Earth-like planet, however we additionally need:
- A planet without just the ingredients for life (which all rocky ones ought to have) but where life truly took off,
- Where no catastrophes stopped it altogether, but where it evolved into advanced, diverse, multicellular organisms,
- And where, maybe with only minor variations, we might survive and thrive on the surface.
- If we get very, very lucky, we’d find a bonus step in there as well: where one of those advanced life forms became a technologically advanced civilization, as we’re still in the process of becoming.
Chances of Finding Earth-like Planet
Now how likely is it that there is another Earth-like planet within the galaxy where all that has happened? Or within the entire Universe?
While we do not yet know, there’s one thing very intelligent we will say about it:
According to analysis by Adam Frank and Woody Sullivan, if humanity is not a rarity within the Universe, that means that the likelihood of these 3 huge steps — life takes off on a world, life evolves into advanced organisms, and one such life form becomes technologically advanced — should be a minimum of 2.5 × 10^-22.
And if we’re not a rarity within the galaxy it should be a minimum of 1.7 × 10^-11. But it may be a lot of, a lot of higher, particularly if we do not require a technologically advanced civilization.
The ingredients for life are everyplace we look.
From molecular clouds in interstellar space, or secured within asteroids or within the frozen worlds of the Kuiper belt.
Our own solar system might have life in underground oceans on Europa or Enceladus, in the cloud-tops of Venus, beneath the surface of worlds like Mars, or perhaps with a completely different chemistry on a methane-rich world like Titan.
If the chances of a habitable-zone world being truly habitable by humans is even one-in-a-million, then there are tens of thousands of worlds within the Milky Way Galaxy alone that might be our Earth-like Planet, and the nearest one is likely under 1,000 light years away!
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