Top 8 strangest exoplanets

Worlds that elude our imagination.

Composition of exoplanets. Visualisation by Martin Vargic.

Super-Earth, Twin Earth, habitable zone, liquid water.

In the 1990s, when we discovered the first exoplanets — planets outside our solar system –we started frantically looking for a rock similar to ours which could host life, similar to ours.

And that’s perfectly reasonable.

Finding any life out there, even tiny microbes, would be humanity’s biggest discovery yet.

But do you know that there exist planets utterly unlike ours? And unlike any object in our solar system? Planets made of diamonds and planets where it rains glass?

Let’s look at 10 of the weirdest exoplanets we’ve discovered so far (and which are very unlikely to host any form of life we would recognize as such).

2mass J2126–8140 — Far from home

Artist’s impression of 2mass J2126–8140. Image by NASA.

You know Earth goes around the Sun in 365 days, right? Pluto, being 6 billion kilometers from the Sun, needs a bit longer — almost 250 years. Which might seem a lot. But there are some planets with orbits that make 250 years seem like a fraction of a second.

2mass J2126–8140 lies about 100 light-years from us and for a long time, scientists thought it was a homeless world, wandering the galaxy without a host star.

But it turns out the planet is not free-floating after all — it just lies very, very far away from its star, about a trillion kilometers away, actually.

This makes it the planet with the longest orbital period known so far: It takes it a million years to go once around its star.

55 Cancri e — A couple of diamonds for the road

Illustration of 55 Cancri e. Image by NASA.

This super-Earth is located about 40 light-years from us in the constellation Cancer. It orbits its host star in just 18 hours, which means it lies extremely close to it.

Its surface temperature? Nearly 4,900 °F (2,700 °C) — enough to melt iron.

Many mysteries surround 55 Cancri e and its characteristics. Astronomers have several theories about its structure and atmosphere.

Some observations suggest the planet is entirely covered with an ocean of lava, while others propose its interior is mostly carbon — in the form of diamonds.

I bet some would love to mine this curious world, if they could.

Gj-504b — Pink is the new black

Illustration of Gj-504b. Image by NASA.

This massive giant — 4 times the mass of Jupiter — lies almost 60 light-years away. So where does that lovely dark magenta hue come from?

Well, this world is very young — only about 160 million years. This makes it very hot — intense heat from its formation is making it glow with a pink shade.

Studying such planets is very insightful because it lets us see what our system might have looked like in its youth.

Gliese 436 b — I’ll have some burning ice, please!

Gliese 436 b imagined by an artist. Image by NASA.

This Neptune-sized world lies about 30 light-years from our solar system. It orbits very close to its star, meaning its surface temperature is seething. Any water on it should logically evaporate.

But that’s not the case.

Gliese 436 b’s surface is actually covered in burning… Ice. Yes, you read that correctly. How can this be?

Well, small planets located close to their star, like Mercury, have their atmosphere stripped away. But Gliese 436 b is a massive planet. It is not only capable of retaining its hydrogen atmosphere, but its gravitational field actually compresses the water on the surface into a solid state.

So we get an ice-like state reaching extreme temperatures.

Do you know that, at least theoretically, there are about 300 types of ice?

Of course, the one on Gliese 436 b is not the same as ice we put in our drinks on a hot summer day. In fact, the only ice existing on Earth is called Ice I and becomes solid due to temperature. The ice on Gliese 436 b is in a solid state due to pressure.

Like carbon transforms into diamond under extreme pressure, water can turn into very dense solid states, denser than the ice we know.

There are some really bizarre scenarios possible when you venture into the galaxy.

Hd 189733b — Ouch!

Artist’s impression of Hd 189733b. Image by NASA.

Lying 65 light-years away in the constellation Vulpecula, this world is a hot Jupiter — a gas giant orbiting close to its star.

Don’t let its beautiful blue shade fool you — this planet is a ruthless killer.

For one, the weather on it is murderous. The winds blow at 5,400 mph (8,700 km/s).

But that’s not all.

That nice blue color? Those are clouds of silicate particles, meaning it doesn’t rain water — it rains molten glass.

Winds of glass blowing at seven times the speed of sound? A real world of horror.

Kepler-78b — Don’t stand so close to me!

Kepler-78b imagined by an artist. Image by NASA.

This Earth-sized world, located 400 light-years from us in the constellation Cygnus, has similar mass, radius, density and structure as our planet.

This encouraging information could make us all excited, thinking we might have finally found our kin.

But there’s a catch.

The planet orbits its star every 8.5 hours — meaning it’s a blazing inferno and definitely not suitable for what we call life.

It is still a mystery for scientists how the planet could have formed or moved so close to its star.

Psr B1620–26 B — Milky Way’s Methuselah

Illustration of Psr B1620–26 B. Image by NASA.

This giant — more than twice as massive as Jupiter — lies 12,400 light-years from us and is unusual for several reasons.

First of all, it orbits a peculiar pair of dead stars — a pulsar and a white dwarf. It is the first confirmed exoplanet with such an orbit.

Secondly, it’s old, very old. At 13 billion years, it is more than twice as old as Earth, and the oldest exoplanet ever discovered. It’s about as old as a planet can be, given we’ve got the age of the universe right.

It formed just a billion years after the Big Bang, giving scientists reasons to believe that planets formed rapidly in this period and that they must be very abundant in the universe.

TrES-2b — Darker than a moonless night

TrES-2b illustrated by an artist. Image by NASA.

TrES-2b is another hot Jupiter — a gas giant lurking close to its host star. Why is it special? Because it’s darker than coal.

Lying about 750 light-years away in the direction of the constellation Draco, this giant only reflects 1% of the light it receives — making it the darkest known exoplanet.

As always, scientists have theories, but the mystery behind this pitch blackness remains.

Part of the answer is probably some light-absorbing chemical in the planet’s atmosphere, such as vaporized sodium and potassium or gaseous titanium oxide. But this doesn’t provide a full explanation.

There has to be some other chemical lurking out there that hasn’t crossed our mind yet.

Bottom line

Our solar system might not be as typical as we once thought. The more we look, the more astounding and strange worlds we discover.

The incredible variety of exoplanets can make us wonder if life can truly spur systematically throughout the universe, or if the conditions on Earth are extremely special and rare.

These planets are all located in our Milky Way galaxy. So far, we haven’t confirmed any extragalactic planets, those in other galaxies, although there are some promising candidates.

What other mysterious worlds will we uncover when our technology lets us venture into unexplored lands?

And will we someday come to a conclusion that we actually are alone?

Thank you for reading my story!