For thousands of years, astronomers had only the planets of our solar system to study. The first planets were discovered through the strange movement they exhibited in the night sky, different to the other stars. Greeks first referred to these irregular stars as wanderers, as translated from the old Greek word 'planan'.
The incredibly complex nature of planetary systems were first hinted at when Galileo looked at Jupiter through a telescope and noticed that celestial bodies orbited the gas giant, discovering what would eventually be referred to as the Galilean satellites.
In 1994, the first planet outside of our solar system was discovered. Dr. Alexander Wolszczan observed unusual variations in the signal of a pulsar known as Beta Pictoris, proving the existence of up to three planets in orbit. Since that discovery, at least 1,888 more exoplanets have been revealed, leading to a revolution in the way scientists understand planetary formation - and even the evolution of the universe as far back as 13 billion years.
The most bizarre planets in the known universe sometimes sound more like than science fiction than hard science, occasionally confounding researchers simply through their existence.
10 Gliese 581C: The Murder Planet
Similar to other planets that are tidally-locked, Gliese 581C is forced to face one way as it orbits its red dwarf star. This means that the side facing the star is scorching hot while the dark side is constantly frozen.
Nevertheless, scientists speculate that a portion of Gliese 581C is habitable - in fact, this planet is believed to be the best candidate for human expansion. Living on this surface would be reminiscent of hell, partially due to the fact that a red dwarf star bombards the planet with red and infrared light, leading to plants that would likely have to adapt to the flood of infrared light by turning black.
9 HD 106906 b is the Loneliest Planet
This charming planet hangs out in the Crux constellation, approximately 300 light years from the Earth. Over 11 times bigger than Jupiter, this "Super-Jupiter" class planet is a discovery that confounds modern astronomers.
Despite its immense size, the planet orbits its star at a distance 20 times greater than the space between the Sun and Neptune, which is about 60,000,000,000 miles, making it one of the loneliest known planets in the universe.
Astrophysicists marvel at this outcast because Jupiter-style planets typically need to be closer to their star to gather enough raw material to form. Another hypothesis - that HD 106906 b is a failed star - would challenge binary star theory because the loneliest planet is considered too small for binary formations.
8 TrES-2b: The Black Hole Planet
Close to the size of Jupiter, located about 750 light years away in orbit of a sun-like star, TrES-2b is a planet that absorbs so much light that scientists consider it the darkest planet in the known universe. Despite the fact that it's a Jupiter-class gas giant, it reflects less than 1 percent of the light that strikes the planet, compared to a reflection rate of around 33% for Jupiter.
As a result, the planet is darker than coal or black acrylic paint, leading to speculation that the atmosphere is laced with a chemical or mix of compounds yet to be discovered. TrES-2b isn't entirely dark - it's hot enough, at 1,800 degrees Fahrenheit, to emit a dull, reddish glow, likely only visible because the planet absorbs so much of its oncoming light.
7 Planet Methuselah is a Billion Years Younger than the Universe
Planet Methuselah - also known as PSR 1620-26 b - is so old that it defies traditional astrophysical models. Traditionally, it was thought that a planet can't be 13 billion years old because of a lack of materials that planets needed to form during that time in the universe.
Yet, Methuselah is nearly triple the age of Earth and was likely formed only one billion years after the big bang. Planet Methuselah roams among a globular cluster of stars, locked together by gravity in the constellation of Scorpius. Within the cluster, Methuselah orbits a binary star system consisting of a white dwarf star and a pulsar.
6 Planet Osiris Ignores the Lessons of Icarus
The first exoplanet discovered in transit of its orbiting star, Osiris, otherwise known as HD 209458b, is located 150 light years away in the constellation of Pegasus. About 30% larger than Jupiter with an orbit that's one-eighth the distance of Mercury from the Sun, the temperature of this planet is around 1,832 degrees Fahrenheit. The heat and pressure exerted on this gas planet has resulted in a significant evaporation of various atmospheric gases, which stream out from the planet's gravitational field like air from an invisible balloon. Osiris stunned astronomers and astrophysics experts when hydrogen, oxygen and carbon were detected rushing away from the planet, leading to an entire new type of planet classification, referred to as chthonian.
5 The Rock Showers of Planet CoRoT-7b
CoRoT-7b was the first rocky planet discovered in orbit of another star. Astronomers believe it used to be a giant gas planet similar to Saturn or Neptune, before its layers of atmosphere and gas were stripped away because of the planet's close proximity to a star.
Due to the fact that the planet is tidally-locked, the part of CoRoT-7b that faces the star is 4,000 degrees Fahrenheit while the dark side of the planet reaches temperatures as frigid as 350F. These conditions contribute to rock rain, where vaporized rock falls to the surface of the planet as liquid rock rain, eventually hardening into solid stone before making impact.
4 HAT-P-1 is Bigger than Uranus and Floats in Water
A recent discovery by the Harvard-Smithsonian Center for Astrophysics, HAT-P-1 is a gas giant half the size of Jupiter that weighs roughly the same as a ball of cork. This incredibly odd planet has caused an uproar in the halls of academic astronomy because it's classified as a "hot Jupiter" planet that's nearly 25% larger than models estimate.
The controversy has astrophysicists scrambling to find a reason why the planet has swelled beyond the established norm. In the distant future, perhaps humanity will be capable of transporting a swimming pool half the size of Jupiter 450 light years in order to test how well the planet floats in water.
3 55 Cancri e is worth $26.9 nonillion dollars
A "Super-Earth" class planet that's roughly twice the size of Earth with temperatures that reach 3,900 degrees Fahrenheit, 55 Cancri e was discovered in 2004. After years of observation, astronomers believe that this big, rocky planet is made mostly of carbon that turned into diamond and graphite.
According to the current market value of diamond, this would make 55 Cancri e worth a total of $26.9 nonillion dollars, which is about 384 quintillion times more than the Earth's paltry GDP of around 74 trillion USD.
According to Forbes, only 0.182% of 55 Cancri e would need to be mined in order to pay back the total debt of all the governments in the world, which hovers close to $50 trillion USD. Investors should note that this potential mining project is only 40 light years away and shrouded in scientific controversy.
2 J1407 b Features Planetary Rings 200 Times Larger than Saturn
Discovered in 2012 with its data only recently compiled and submitted for publication, planet J1407 b is located 400 light years from Earth and boasts a system of planetary rings that are 200 times bigger than the ones orbiting Saturn.
The Saturnian ring system of J1407 b is so large that if Saturn had a ring system of similar size, it would dominate the Earth's sky and appear much larger than the full moon. Scientists have observed gaps in the ring systems, leading them to believe that these gaps represent exomoons orbiting this exoplanet. The ring system is so large that astronomers observed a 56-day eclipse of the star that J1407 b orbits.
1 Gliese 436 b - A Burning Orb of Ice
Another crazy planet classified under the Gliese catalogue of nearby stars, Gliese 436 b is roughly the size of Neptune. It's about 20 times larger than the Earth, but orbits only 4.3 million miles from its star - compared to the Earth, which orbits roughly 93 million miles from the Sun.
The resulting temperature on Gliese 436 b is a consistent 822 degrees Fahrenheit. The ice that exists on the planet is kept together by immense gravitational forces. These forces prevent water molecules from evaporating and escaping the planet, instead becoming tightly packed deep within. The burning ice in Gliese 436 b is referred to as ice-ten, reminiscent of but much hotter than the ice-nine found in Kurt Vonnegut's Cat's Cradle.