It’s actually not a long time ago that we started the journey of Space exploration with modern techniques and advanced technology. We invented the Hubble Space Telescope, sent satellites and probes to the outer reaches of the space to discover new worlds. Soon we discovered that our Sun is not the only star to host planets, in fact, there are 100 billion of them (estimation) in our galaxy alone.
By the end of the 20th century, we had already detected thousands of exoplanets outside our solar system. Even though we haven’t found the perfect one yet that could support life, we have come across some of the strangest and extreme planets. Well, we have already covered some of the hottest planets out there, it’s time for us to know more about colder ones. This list will introduce you to some of the Coldest Planets in the space, and we like to call them cold hell.
Surface Temperature: Unknown
Discovered only in 2017, OGLE-2016-BLG-1195Lb is deemed to be one of the coldest planets discovered to date. Located in the vast reaches of our galaxy at the distance of 13,000 light years from the Earth, this planet was discovered with the help of delicate method known as the gravitational microlensing used by Spitzer Space telescope and Korean Space Agency.
It is orbiting a star, OGLE-2016-BLG-1195L, which is less than 8% of the total size of the Sun. This discovery led scientist to the conclusion that instead of a star, the host might just be a brown dwarf, an ultra-cool brown dwarf. So there is a huge amount of chance that OGLE-2016-BLG-1195Lb is an extremely cold planet and far too extreme to be habitable.
Image Courtesy: NASA
Surface Temperature: 165 Kelvin
We all know that Jupiter is the largest planet in our solar system, it’s a gas giant with mass 1/1000 of the Sun, but it also has one of the coldest temperatures among the discovered planets. This cold temperature is mostly due to the presence of ammonia and ammonium hydrosulfide in its atmosphere.
Recently, a cold vortex has been discovered at the Jovian North pole in its thermosphere. The vortex, also known as “Great Cold Spot” is 12,000 km wide and 24,000 km across. Based on observations, the temperature differences between the cold vortex on Jupiter’s north pole and other parts of the planet is expected to be more than 200 °C.
The discovery of the Jovian cold vortex was done with the help of VLT or Very Large Telescope situated in Chile.
Surface Temperature: 134 Kelvin
Do you ever wonder why Saturn has pale yellow hue when you see it in pictures and videos? Well, it’s mainly due to the variable gases present in the Jovian upper atmosphere especially ammonia. The presence of ammonia crystals and ammonium hydrosulfide in the planet’s atmosphere has greatly contributed towards the overall cold temperature of the planet.
In 2007, researchers discovered a warm polar vortex near Saturn’s south pole. Even though, there are few other polar vortices present in the solar system, it’s the only known hot polar vortices. Temperature differences inside the vortex is huge and a difference of -60 °C can be registered. It is expected to be the hottest spot on Saturn.
Surface Temperature: 76 Kelvin
Put aside all the memes and all the jokes about its name, Uranus is without a doubt a freezing hell, where none of us wants to go. In respect to the composition, Uranus is more similar to Neptune than the other gas giants in our solar system – Jupiter and Saturn. It contains more amounts of methane than all three of them.
The vast amount of methane and ammonium hydrosulfide present in the upper atmosphere and water in the lower reaches of the planet is the reason why Uranus is one of the coldest planets in our solar system with temperatures reaching below -200°C (-224°C to be exact).
Surface Temperature: 72 Kelvin
Unlike all the other planets in our solar system, Neptune was the only planet whose discovery was done by mathematical predictions rather than by traditional empirical methods. It was only during the late 1980s, that astronomers were able to discover its various characteristics for the first time ever with the help of Hubble and Voyager 2.
Neptune has almost 17 times more mass than that of the Earth and it’s more massive than Uranus. With massive amounts of ammonia and methane present in its atmosphere, Neptune is undoubtedly one of the coldest planets in our solar system and among the coldest in the observable universe.
2. PSR B1620-26 b
Surface Temperature: 72 Kelvin
Located at the distance of 12,400 light years away from the Earth the exoplanet PSR B1620-26 b is very popular among the astronomers and space lovers due to its extreme old age, due to which the planet has earned itself a nickname “the Genesis planet.” But what you might not know is that it’s one of the coldest planets ever discovered.
The planet orbits around two stars in a circumbinary system consisting of a pulsar and a white dwarf. The distance between the planet and the host stars is around 3.4 billion km or 23 AU, slightly shorter than the distance between Neptune and the Sun.
Surface Temperature: 50 Kelvin
OGLE-2005-BLG-390Lb is not just the coldest but with an estimated distance of 21,500 light years from the Earth, it’s also one of the farthest exoplanets discovered to date. Although the planet is thought to be orbiting an M type red dwarf, there is a slight possibility that its host star is actually a neutron star or even a black hole.
Due to its vast distance, it has been subjected to many speculations over the years According to some researchers, it has a rocky core, quite similar to the Earth and also a negligible atmosphere. If it really does, then it’s more likely that the planet’s surface is made up of ammonia, methane and other frozen volatiles. But if isn’t, then it’s more likely that the planet is a gas giant.
One more fascinating characteristic feature of this planet is its large distance from the parent star, which is very uncommon in the case of relatively small planets.