The study of planets outside of the solar system is still in its infancy.
The first exoplanet wasn’t officially recorded until 1992, and there are still less than five
thousand confirmed exoplanets in space. That’s despite various estimates claiming
that there are many billions of them still to be discovered in the universe. Even so,
every so often we find one that particularly piques our interest…
and that’s exactly what Gliese 486b has done! This is Unveiled, and today we’re answering
the extraordinary question; did scientists just discover the best ever super-Earth?
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A super-Earth is any exoplanet with a mass up to ten times greater than our Earth’s. But, really,
that’s all. Contrary to common misinterpretation, a super-Earth isn’t automatically similar to our
own world in any other way. For example, it isn’t necessarily habitable, and it doesn’t necessarily
have Earth-like environments. Sometimes, a super-Earth is also Earth-like, but most
of the time it isn’t. And that’s true of Gliese 486b, an exoplanet recently discovered by a team
of scientists working mostly in Europe. It’s a totally alien place, described by many as hellish
and almost certainly inhospitable to life as we know it. But it’s also just twenty-six lightyears
away from us… and it’s set to become one of the most studied objects in the sky.
The close proximity of Gliese 486b is one of the main reasons why scientists are so excited by it.
Twenty-six lightyears may sound like a lot, but in the vast expanse of space
it makes us next-door neighbours. This particular planet orbits the M-dwarf star, Gliese 486, in
the Virgo constellation. But it’s also positioned in such a way that it’s easy to track from Earth.
All of which means that it’s far easier to get to know this planet than most,
using a number of astronomical spectroscopy techniques to determine particulars about its
radiation, density, atmosphere, and more. But, as mentioned, Gliese 486b hardly has
second home potential for us, the human race. Our particular form of life could never hope
to survive there, seeing as it offers surface temperatures upwards of four hundred degrees
Celsius, gravity that’s seven times stronger than it is on Earth, and an orbital period of
just one-and-a-half days. If a human being lived there, they’d burn to death, they’d weigh a lot
more whilst doing so, and they’d have a sort-of birthday every few hours. The landscape is
predicted to include violent volcanoes and rivers of molten rock, so it’s not exactly welcoming.
So why, again, are scientists still so interested in Gliese 486b? If it’s such a terrible place for
us in general, why has it also been described as a Rosetta Stone of space exploration? Along with
its close proximity, that extremely short orbital period is crucial, too. One of the ways in which
we can observe this world is transit spectroscopy - which is when we glean information every time
a planet passes in front of its star (from our perspective). With Gliese 486b, this is happening
extremely frequently, so we get a really steady stream of data. In many ways unparalleled to
anything else we have. Then there’s also the fact that astronomers are confident that this world is
rocky (like Earth) and that it has an atmosphere to speak of, which many confirmed exoplanets
don’t. Another cause for scientists to rejoice! For these reasons, those behind its discovery have
suggested that Gliese 486b could become a standard-bearer for exoplanet study.
The knowledge we gain of it could go on to shape how we scrutinise thousands of other
planets in the future. Thus, the Rosetta Stone comparison. The Rosetta Stone is a massive,
inscribed rock discovered in 1799 which originally enabled us to translate ancient languages;
Gliese 486b could be the space discovery we look back on in the future that finally
allowed us to read the galaxy in detail. As a result, Gliese 486b has already been lined
up as potentially one of the first primary targets for the James Webb Space Telescope. The James Webb
has suffered various setbacks and delays over the years but is currently scheduled to finally launch
in late 2021. It’s a ten-billion-dollar, flagship mission for NASA, planned to take over from the
Hubble Space Telescope in the long-term. If and when it does eventually get off the ground,
space enthusiasts can expect to regularly hear about it over the next few decades,
thanks to the endless stream of images it’ll produce. The James Webb will observe the universe
with greater clarity than any other piece of technology has ever been able to do before now…
and will be able to snatch glimpses of even the most distant galaxies in existence. The mere
twenty-six lightyears between us and Gliese 486b, then, will be a breeze for it. And among the first
questions it will be looking to answer are… what does this world tell us about all other worlds?
So, it’s very much a case of watch this space when it comes to this particular exoplanet.
But, if this is to become the greatest, most influential super-Earth ever discovered, then
what other worlds is it beating to the privilege? The first super-Earths (of any type) detected by
us came shortly after the first exoplanets in general were found, again in 1992. These were PSR
B1257+12 B (nicknamed Poltergeist) and PSR B1257+12 C(nicknamed Phobetor). They both orbit
the same pulsar about 2,300 lightyears away from Earth - almost one hundred times further away than
Gliese 486b is. Neither, though, are predicted to be especially Earth-like in any other ways.
The first super-Earth thought to be in a habitable zone came in 2007,
with the discovery of Gliese 581c - a far-off world with about five times the mass of Earth,
moving around the very inner edge of the so-called Goldilocks Zone in its star system. Gliese 581c is
also relatively close by, at just over twenty lightyears from us. The downside in terms of
our search for alien life (or planets that could host life) is that it’s tidally locked, meaning
one side always faces the star and the other side always faces away from it. At this early stage,
scientists think the same could be true for Gliese 486b, too. In general, while life could
exist on such a world, it is deemed less likely. Elsewhere, the Kepler Space Telescope provided
its fair share of super-Earth contenders, as well. Launched in 2009 and deactivated in 2018,
it operated for almost ten years, during which time it registered exoplanets including
Kepler-440b and the slightly less memorably named, HIP 116454 b. Discovered in 2015, Kepler-440b
ultimately generated more interest. It was again detected using transit spectroscopy…
and is again situated in a habitable zone. The downside in terms of humankind ever reaching it,
though, is that it’s 850 lightyears away from Earth. This time more than thirty times as far
as Gliese 486b is, and Kepler-440b performs far fewer transits, too.
We can begin to see, then, why scientists are so particularly enthused by this latest super-Earth
on the scene… compared to those that came before it. Gliese 486b could represent
that rarest of astronomical opportunities; a close by, alien world we can reliably observe
in detail. Somewhere outside of the solar system that we can start to truly visualise.
Unfortunately, at this stage we have no means to even begin to plan a physical visit to a place
so far away. Twenty-six lightyears distance means twenty-six years of unbroken lightspeed travel to
get there. Considering that, at present, we can only travel at just a fraction of
the speed of light for just a tiny period of time - and even then, we’re only talking tiny,
uncrewed probes - a mission to Gliese 486b isn’t going to happen for generations. If ever.
And this isn’t unexpected news. We know that the universe, even just the Milky Way galaxy,
is almost incomprehensibly huge. We know that our place on this planet orbiting this star is
but a miniscule component within the cosmos as whole. But, gradually, we’re gaining more of an
understanding about what else is out there. About other worlds orbiting other stars. In some ways,
Gliese 486b is just the latest in a lengthening line of distant space discoveries…
and yet parts of the scientific community remain just a little bit more
optimistic than usual that this particular development could be a key breakthrough.
How do you feel about it? Will you be keeping tabs on Gliese 486b over the coming years,
and using it to better understand what life might be like outside of the solar system?
As we said at the top of this video, the study of exoplanets is still in its infancy…
but the landscape is changing at an increasing and exciting pace.
And that’s why scientists may have just discovered the best ever Super-Earth.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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