For a long time, Earth was the weirdest planet we knew about. In our little corner of the universe, where Mercury is the hot one, Jupiter is the protective bigger brother, and Pluto is the one we kicked out of the club for breaking the rules, Earth is the crazy cat lady, hoarding billions of life forms. But over the last 20 years the family has expanded to include over 3,600 exoplanets, and some of these distant relatives are far more unusual than we could've imagined.
There are planets where it rains rocks, planets where the wind whips around at seven times the speed of sound and planets where one year can last almost a million years. Suddenly Earth seems pretty boring, so let's take a quick tour of some of the most bizarre exoplanets that have been spotted so far.
The Earth-sized Iceball
With a name like a cat walking across a keyboard, OGLE-2016-BLG-1195Lb is about the same mass as Earth and orbits at roughly the same distance from its star. But that's where the similarities end: its host star is so dim that scientists can't decide whether it should even be classified as a star. As a result, it's giving OGLE the cold shoulder, meaning the planet is probably chillier than Pluto.
Way up the other end of the temperature scale sits the balmy, Venus-like GJ 1132b. In the near future, this exoplanet might hold the honor of being the first planet (outside of Earth, of course) that we detect to have gaseous oxygen in its atmosphere. Unfortunately, that doesn't mean it's life-friendly: a runaway greenhouse effect means this steamy atmosphere would be hot enough to melt the rocky surface, creating oceans of magma.
The Styrofoam giant
It may look huge and imposing, but KELT 11b is just a big softie at heart. Despite being 40 percent bigger than Jupiter, it only has about a fifth of its mass, giving it the density of styrofoam. Orbiting a bright yellow subgiant sun once every five days, this mega marshmallow will continue to roast for the next hundred million years, before the star swallows it up.
Windy with a chance of gems
Another gas giant, HAT-P-7b is tidally locked to its star, meaning half is forever stuck in scorching sunlight at about 2,600° C (4,700° F), while the other is bathed in eternal night. That creates wild winds that quickly carry clouds around the planet – clouds which, we might add, are made of rubies and sapphires.
A diamond in the sky
Ruby and sapphire clouds are impressive, but in terms of bling, a planet orbiting the pulsar PSR J1719-1438 has it beat. Mostly made of oxygen and carbon, the planet is fairly small but incredibly dense, and that means it probably takes on a crystalline structure – so the entire planet (or at least part of it) could be one huge diamond.
That's just a small selection, but with the number of exoplanets discovered growing almost daily, we can't wait to see what other planetary surprises the universe throws up in the future.