Despite the great silence we hear when we look out into space, we do at least know that
there are other potentially habitable planets out there.
And perhaps, with them, come entire alien races.
We’ve been desperately searching for any sign of intelligent life for decades now,
but with so many planets in the sky, it’s hard to know where to start.
Excitingly, a new study might change all that.
This is Unveiled, and today we’re answering the extraordinary question; are 29 alien planets
watching Earth right now?
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Conducted by astronomers at Cornell University, and published in the journal “Nature”
in June 2021, the study at the heart of today’s video is titled; “Past, Present and Future
Stars That Can See Earth as a Transiting Exoplanet”.
And it may yet go down as a key moment in the search for extraterrestrial intelligence.
In short, the study pinpoints 29 potentially habitable exoplanets that might be (or might
have been) observing Earth from afar.
So, let’s scale that back.
An exoplanet is a planet that science has detected and confirmed from outside the solar
system.
They’re extremely difficult to spot, which is why the number of them is so low compared
to the estimated number of potentially habitable worlds in just the Milky Way.
There could be as many as 300 million potentially habitable worlds in our galaxy, but as of
2021 there are less than 5,000 confirmed exoplanets.
This study proposes that at least 29 of those are both potentially habitable and within
range to be watching over us.
To be potentially habitable, the planet must be within the habitable zone of its star,
and rocky like Earth is.
To be within range, it needs to be in what’s known as “Earth’s Transit Zone” - or
the EZT.
This means that they’re in a position in space where it’s possible to witness Earth
transiting in front of the sun, which would enable a hypothetical observer on that planet
to detect us.
The 2021 study found that more than 1,700 stars were in this position.
But finally, the study sharpened its criteria by adding that any potentially habitable exoplanet
within the EZT also needed to be potentially able to send and receive radio messages within
a range of about 100 lightyears - i.e. within range of Earth’s own radio history.
And, with that, we reach the magic number of 29.
But still, how did we get there?
Planetary transits are the most reliable way we currently have to find exoplanets.
They’re what many of our most cutting-edge telescopes are designed to spot, when a passing
object obscures the light from a distant star.
And we can potentially yield a lot of information from a transit, including an exoplanet’s
size and how far away from its parent star it is.
But there are also plenty of things we’re not yet able to determine.
For example, we don’t yet have telescopes powerful enough to actually see exoplanets
as anything other than shadows and small dots… so we’re still so far removed from them.
We can’t directly analyse to see whether there’s plant life, liquid oceans, or even
alien cities.
We also can’t yet accurately pinpoint the composition of an exoplanet’s atmosphere,
to list the chemical elements and molecules that exist there.
When the much-delayed James Webb Space Telescope finally launches, reportedly by the end of
2021, however, it will carry a Near-Infrared Spectrograph… and we should then be in a
better position to study the atmospheres of exoplanets.
Similarly, the Extremely Large Telescope in Chile - scheduled to begin operations in 2025
- will be able to image exoplanets in more detail than ever before, capturing shots in
more than 15 times better quality than those from the Hubble Space Telescope.
But that’s for the future and this is now, and though we have a range of about 100 lightyears
for the 29 planets highlighted by this study, some of them are significantly closer than
that – including one, orbiting a red dwarf named Ross 128, that sits only 11 lightyears
away from us.
It was also found that there are other planets that are just as close, but that aren’t
in a position to witness Earth’s transits right now.
The reasons for this differ, but it means that were we to conduct a similar study again
in 10 years’ time, or 100, then that number 29 could well rise.
Equally, it means that there could be close planets out there (potentially hosting alien
life) that we haven’t yet been able to see transit.
And perhaps some that can see us… but we can’t see them.
And quickly the vastness of space takes hold, because we’re still only really contemplating
this on a galactic scale, within the Milky Way… and the Milky Way is just one of trillions
of galaxies in the universe.
So, what can we do with this information?
It’s still extremely difficult to put it to use when it comes to communicating with
other planets and potentially other lifeforms.
If 29 (or more) planets could be watching Earth right now, they may also have tried
to send us a message already – it just missed.
Because that’s not unlikely.
Those alien planets are spinning around their stars at tens of thousands of miles an hour,
while their star also travels through the Milky Way at a blistering speed… all while
we’re all the way over here doing exactly the same thing.
There’s no doubt that our technology is improving, nor that their technology could
already be better than ours, but clearly landing communications exactly where they’re supposed
to go is no mean feat.
Although, really, that’s one reason why this 2021 study is so important.
Now that we’ve pinpointed 29 planets at least that are potentially habitable and potentially
observing us, we can specifically study and target these 29 in the future.
At present, space is still silent to us, but we’re suddenly one step closer to opening
up a genuine communication link.
What’s perhaps surprising, though, is that from another planet’s point of view Earth
might not appear a dead cert to host life.
We obviously know that there is life here, but say at least one of the 29 is host to
intelligent beings also advanced enough to have studied and identified exoplanets…
it’s possible that they will have set their sights on another world that isn’t Earth?
By some estimates, for example, Earth only just makes it into our solar system’s habitable
zone – right on the inner edge.
For a far-off onlooker, then, we might be deemed too close to the sun to be worth taking
a risk on.
Or they could have a completely different interpretation of what the habitable zone
should be, based on the fact that they themselves perhaps live further away from the stars in
their own systems, and so they would never even consider us as being of particular interest.
Maybe Mars would be more their thing.
And while we can be fairly certain that they won’t find life on the Red Planet, perhaps
they’ve been mistakenly beaming messages to our closest neighbour for years.
Of course, there are other nearby worlds they could be looking at, too.
We know that Venus isn’t without signs of life, for example… even if it is almost
certainly devoid of life itself.
Or perhaps our hypothetical alien onlookers know that gas giants (or their moons) are
actually a better bet for life to exist, and so they’re more taken by Jupiter and Saturn.
In the cases of Venus and Mars, in particular, there’s also the fact that most scientists
agree that at one time during the lifetime of the solar system both have been habitable.
Were an alien race to be working from out-of-date information, then - to the tune of billions
of years - it would perhaps be understandable if they went and focussed their attention
elsewhere.
Naturally, the other possibility is that at least one of the 29 planets suggested by the
2021 study is totally in the know and irrefutably certain that life on Earth does exist.
In that case, they could well have their telescopes (or telescope-like technologies) trained on
us right now, watching our every move.
As it stands, we’ll never know… but the fact that we do now have a handful of very
specific exoplanets to target, ones that might be targeting us in return, still serves as
a major step forward in the search for extraterrestrial intelligence.
On a cosmological scale, we’re finally getting to know our neighbours… and we’re getting
closer and closer, with every year, to discovering the truth about nearby, alien life.
And that’s why 29 alien planets might be watching Earth right now.
What do you think?
Is there anything we missed?
Let us know in the comments, check out these other clips from Unveiled, and make sure you
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