These “ Impossible “Planets defy all logic!
Ladies and gentlemen, fasten your seatbelts because I'm going to tell
you something that could sound impossible and unphysical, yet it is completely true.
The smallest planet discovered so far, with a mass
smaller than half that of Earth, is called Kepler 70b, and it is...hotter than our Sun!
It is so hot that scientists couldn't believe their eyes
when they first took a look at the data.
Imagine being an astrophysicist and finding a temperature of 6830°C
for a planet, knowing that your Sun has a surface temperature of 5777°C!
Other known elements for the planet are its orbital period, which is very short, something
like 6 hours, and its radius of 0.75 terrestrial radii. The planet has a mass of 4.45 times that of
the earth. Given all these properties, astronomers think the planet would be the rocky core of a gas
giant with volatile outer layers, that evaporated during the period in which the parent star
went through the red giant phase. If this is true, this is what a planet like Saturn or Jupiter
might look like in the future, when the human race won't exist anymore. At least not on planet Earth,
because the Sun will destroy everything while evolving through the late stages of its life.
Oh, I almost forgot: scientists think the planet is still evaporating, which means that it could
become even smaller as time passes by. But this was just the beginning!
You have literally no idea of how strange the worlds out there can be.
Follow me in this video to get to know more about them.
GJ 504 b, for example, it's a planet that has four times the mass of Jupiter
but is almost the same size. Until now, everything seems quite normal.
The thing is...believe it or not, this planet is pink!
This is quite an unusual colour for a planet, it's so fancy!
Why is that? How is it possible for a planet to be pink?
The planet is about 160 million years old, which makes it a newborn,
much much younger than our solar system's age. When a planet is this young, we know that it
changes a lot in a small amount of time. For example, at this age, a planet is
changing and losing heat of its formation, which indeed gives it a magenta colour.
But this was an extraordinary planet. Let's go to the more normal, ordinary planets.
I'm gonna show you that, even if they seem quite normal, some of them can be really strange.
Take, for example, a Neptune-Like exoplanet, called Waterworld.
It has a mass of more than 8 Earths, and a radius of 0.24 times that of Jupiter.
This planet also contains water, so it might be a promising candidate for life as we know it,
but unluckily it doesn't have a solid surface like Earth.
Moreover, the planet's atmosphere is quite different from the one on Earth. Why is that?
Well, you need to know that Waterworld has extreme pressure and heat,
and so the atmosphere consists of water in plasma form, something so strange that
scientists could not believe it the first time they saw the data. On this planet,
the water is in a constant supercritical fluid form, and the phases of water don't exist.
Let's say this water has some properties of both liquid and gaseous water,
but it's something that we never experienced in any laboratory of river, or sea on Earth.
The planet you're facing right now is called J1407b, and it is one of the
strangest planets ever discovered. It is located about 434 light-years
away from Earth, and if you take a look at it, you will notice it resembles...SATURN!
The only thing is that it's much, much bigger than our gaseous giant.
Astronomers literally struggled to measure its mass,
but it is thought to be something like 10 to 40 Jupiter Masses.
This planet's of course a giant planet, but it's nothing like the planets of our solar system.
In fact, it is much larger than the biggest planet in our solar system.
But maybe the most intriguing feature of this planet is not something related to its size
or mass...what really amazed scientists all over the world is the presence of
an enormous ring system around the planet. Such rings extend for a very long distance,
something like tens of millions of kilometres in diameter!
Better saying, this system of rings is composed of 30 rings, and every ring is actually made of
dust and particles that vary in size and mass. For example, you can find dust of the size of
a micrometre, but also small and bigger asteroids orbiting around this planet.
If you were in a spaceship ready to dive into the atmosphere of this planet, you might want to think
twice before hitting one of these rings. According to some estimates,
the diameter of the entire ring system is something like 120 million kilometres,
which means that this ring system is 200 times larger than the rings around Saturn.
Think about it. If you ever happened to see Saturn through a telescope, you'd have for sure noticed
the shape of the rings around it. Now imagine something 200 times bigger.
It would be dominating our night sky, and it would appear as an object the size of the moon!
However, these rings are not destined to stay like this forever.
Instead, they will change sooner or later, due to the fact that, among these rings,
satellites of the planet will form from dust and particle encounters. As some overdensities grow
up in these rings, they clean up their orbit and usually, the dust being a dragging factor,
such satellites will migrate inside, losing angular momentum by friction with the dust
and thus getting closer to the planet. This is also how Saturn's moons were formed.
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WASP 76-b is an exoplanet that lies about 640 light-years from the sun,
is an "ultrahot Jupiter" that zips around its parent star once every 1.8 Earth days.
This is a really close distance from the star, it has moulded the gas giant into a bizarre hell
world with no analogue in our own solar system. For example, the huge amounts of stellar
radiation that WASP-76 b absorbs have puffed the exoplanet up immensely;
it's 1.85 times wider than Jupiter despite possessing just 85% of that planet's mass.
WASP-76 b is also tidally locked, always showing the same face to its star just as the moon
only ever shows its near side to us here on Earth. And WASP-76 b is incredibly hot.
Astronomers estimate that its nightside, so the coldest one, 1,300 degrees Celsius,
while temperatures on its dayside hover around 2,400 C — hot enough to vaporize many metals.
That's also why, scientists think that strong winds carry vaporized iron from the exoplanet's
dayside to the cooler nightside, where it condenses and falls as molten iron rain.
Basically, on this planet, rains melted iron. Ouch!
============================================================= As you can see, space seems to be
crowded with such bizarre planets. And some of them are so bizarre,
that one could hardly believe these celestial bodies really do exist.
For example, another planet, with a similar name to the previous one, is WASP 107b.
It is a peculiar word because...it has the density of a cotton candy. This can
seem quite normal, but it's not. This actually makes scientists
revise their understanding of how gas giants form. The planet is very close to its star, over 16
times closer than Earth to the Sun. As big as Jupiter but 10 times lighter, Wasp-107b
is one of the least dense exoplanets known to date - a type of planet that astrophysicists
have dubbed super-puff (super puffy) or cotton-candy (cotton candy).
The discovery team carried out an analysis to determine the most likely internal structure
of the planet and came to a surprising conclusion: with such a low density,
the planet must have a solid core of no more than four times the mass of the Earth.
This means that more than 85 per cent of its mass is enclosed in the thick
layer of gas that surrounds this core. By comparison, Neptune - which has a similar
mass to Wasp-107b - has only 5 to 15 per cent of its total mass in its gas layer.
But how can such a low-density planet be formed? And how did it manage to prevent its
huge gas layer from dissolving, especially given the planet's proximity to its star?
Planets form in the disc of dust and gas that surrounds a young star, the protoplanetary disc.
Classical models of gas giant formation are based on what we know about Jupiter and Saturn
and predict that a solid core at least 10 times more massive than Earth is required to accumulate
a large amount of gas before the disk dissolves. Without a massive core, the gas giant planets were
unable to surpass the critical threshold needed to build and maintain their large gas envelopes.
For Wasp-107b, the most plausible scenario is that the planet formed very far from the star,
where the gas in the disk is cold enough and its accretion can happen very quickly.
Thereafter, the planet was able to migrate to its present location,
either through interactions with the disk or with other planets in the system.
Mhhh, speaking of cotton candies I'm getting a bit hungry. What about you?
Anyway, always speaking about weird planets, in 2007, a cool planet,
called Gliese 581 c, was discovered. It is an exoplanet orbiting the red dwarf
Gliese 581, which is a faint star in the Libra constellation, about 20 light-years away from us.
It is classified among the super-earth, and what makes it so special is that
it is considered to orbit into the habitable zone of its planetary system.
It constantly shows one side to its host star,
just as the moon does with the Earth. This phenomenon is known as a “tidal lock”.
The models developed on the evolution of the orbit of Gliese 581 c over time suggest that the tidal
warming resulting from the lock would play an important role in the geology of the planet.
Such models predict that tidal warming would fuel a surface heat flux
three times greater than that exerted by Jupiter on its satellite Io, resulting in significant
geological activity possibly characterized by plate tectonics and intense volcanism
If you land on the light side of it, temperatures are so hot that you would probably instantly melt,
but on the other side, temperatures are so cool that you would probably instantly...freeze.
This means that, even if the planet is said to be Habitable,
only a tiny strip on its surface would be good for life as we know it to grow and develop.
It has indeed an unusual surface!
But don't worry, one day we will develop a technology to both reach that planet
and be able to survive there. I mean, once we landed on that strip, everything will be fine.
Well, in this video we have shown you how, once again, reality can overcome our imagination.
Every now and then, astronomers find something unusual, unexplainable, among exoplanets.
The first thing to do when scientists find something strange is to make sure that the
observations were not affected by errors. Then, if everything was real and the observations were
conducted in the right manner, it comes the time to study these planets in more detail,
in order to understand the physical mechanisms that explain the observed unusual properties.
And a scientist must always be ready to change his mind,
and to criticise the models because our models are not perfect!
This is how science progresses towards its bright future, full of iron rain,
pink planets, better models and who knows, maybe some other form of life.
This, for science, is the era of exoplanets.
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