1The coldest planet in the universe
With a temperature of about 50 degrees above absolute zero (-223 ° C), the extra-solar planet OGLE-2005-BLG-390Lb holds, for the moment, the title of the coldest planet. This world is located 20,000 light years from Earth, in the constellation of Sagittarius, very close to the center of the Milky Way. Its star has a low mass, it is a cold star known as a red dwarf. The most curious thing is that the planet orbits 80 million kilometers from its star, something less than the distance between Jupiter and the Sun. The result is that this planet, which is also popularly known as Hoth(from Star Wars), it is unable to sustain life and most of the gases in its atmosphere would freeze into the snow on the surface. It was discovered in 2006 at the ESO observatories in Chile.
2The hottest planet in the universe
How hot a planet depends mainly on how close it is to its host star – and on the characteristics of the star itself. In our own solar system, Mercury, for example, is the planet closest to the Sun with an average distance of 57,910,000 kilometers. Mercury temperatures on its diurnal side can reach around 430 ° C, while the Sun has a surface temperature of 5,500 ° C. But is this the hottest thing we know? There are stars more massive than the Sun much more ardent. The star HD 195689 or KELT-9, without going any further, is 2.5 times more massive than the sun and has a surface temperature of almost 10,000° C. Your planet, KELT-9b, it is much closer to its host star than Mercury from our Sun (specifically 30 times closer than the Earth of the Sun). So, we have reached the hottest planet in the universe: KELT-9b, which is 650 light-years from Earth in the constellation of Cygnus. Orbits its star every 1.5 days, which results in about 4,300 ° C of temperature; hotter than many of the stars with a mass lower than our sun. To give us an idea, Mercury would be a drop of molten lava at this extreme temperature. In fact, with how close it is to its star, the planet is destined to disappear.
It was discovered in 2016 thanks to the use of the Kilodegree Extremely Little Telescope.
3The largest planet in the universe
We are talking about DENIS-P J082303.1-491201 b, a planet so massive that it is still debated whether it really should be classified as a planet or as a brown dwarf star. The point is that this planet has 28.5 times the mass of Jupiter, which makes it the most massive planet that appears in the NASA exoplanet file. According to official definitions it is an object too massive to be a planet and should be classified as a brown dwarf but, as we say, astronomers can not agree. Your host star is a confirmed brown dwarf.
It is a substellar object that orbits the star DENIS-P J082303.1-491201 about 67.7 light years from Earth in the constellation of Vela. It was discovered in 2013 thanks to the Observatory of the Chair in Chile.
4The smallest planet in the universe
The only natural satellite on Earth, the Moon, has a radius of 1,737 kilometers. For the tiniest planet in the universe is a little larger than our moon and smaller than Mercury. It is Kepler-37b, a rocky world that is approximately 215 light-years from Earth in the constellation of Lyra. Orbit the star Kepler-37 at a much closer distance from what is Mercury than our Sun, so it is too hot to support liquid water and, therefore, the possibility of finding life on its surface. Its average temperature is 426 ºC. It was discovered in 2013 thanks to the Kepler mission.
5The oldest planet in the universe
Also known as ‘ Methuselah’, PSR B1620-26 b is the most ancient planet in the known universe. It is more than 12,400 million years old (it is barely 1,000 million years younger than the universe itself) and it is a gas giant with 2.5 times the mass of Jupiter. It was discovered in 1996 by a group of astronomers led by American astrophysicist Donald Backer, who was examining what they thought was a binary pulsar. Then, it turned out that the stage was made up of a planet orbiting around two host stars, which rotate around each other in the constellation of the Scorpion.
6The youngest planet in the universe
We now travel about 427 light-years away from Earth in the Taurus constellation and we come across the V830 Tauri planetary system, where a young exoplanet of just 2 million years old orbits its host star that has the same mass as our Sun but twice the radius, which shows that it has not yet entered its final training phase. The exoplanet in question holds, therefore, the record of the youngest planet in the known universe and is characterized as a gas giant still growing with three-quarters of the mass of Jupiter at the moment. V830 Tauri b orbits its parent star every 4.93 days at a distance 7 times closer than the planet Mercury with respect to the Sun, so we imagine the warm temperatures of its surface. It is classified as a hot Jupiter and was discovered in 2016.
Other known ‘youngsters’ are TW Hydrae, a star of about 5-10 million years and 80% of the mass of the Sun and the planet that orbits it, K2-33b, a young world that is about 470 light-years away from Earth in the constellation of Scorpio. The planet is 50% larger than Neptune and could still be in its formation stage.
7The planet with the most violent climate
It is likely that as we continue to explore the universe, we will observe weather patterns that surprise us because of their particularities but, for the moment, they are too far away for us to analyze their climate. Therefore, the planet with the most extreme climate of the known universe is in our solar system: it is Venus. This planet that lacks natural satellites and named in honor of the Roman goddess of love ( Aphrodite in Greek mythology), has anything but a romantic climate. The planet is enveloped in clouds of sulfuric acid whose winds reach hurricane speeds of up to 360 km/h. Its atmosphere is almost 100 times denser than that of the earth and replete with carbon dioxide in its majority. The resulting greenhouse effect poses a bucolic scenario of temperatures of 462 ° C on the surface. The infernal days of Venus are also very long since it has the longest day in the solar system: 243 Earth days.
8The planet with the most variable temperatures
Going from a hellish heat to an icy ‘glacier’ in a few hours? The day and the night seem to fight in duel in Mercury, because the diurnal and nocturnal temperatures do not leave imperturbable to anybody. By day, the planet closest to the Sun, specifically in the Caloris basin of 1,550 kilometers in diameter, we can ‘enjoy’ about 430 ° C in temperature. When night falls, the temperatures suffer a drop of 600 degrees Celsius, being observed in Mercury the – 170 ºC of temperature. It is, without doubt, the planet with the greatest difference in temperature. The reason, apart from its proximity to the Sun, is because Mercury has almost no atmosphere, so it is not able to retain heat. If we landed on Mercury, or we would burn in flames or die frozen.
9A monstrous planet
Astronomers have discovered something they thought was impossible: a gas giant the size of Jupiter orbiting a red dwarf with half the mass and size of the Sun. This monstrous planet is called NGTS-1b and breaks records, because the planet is excessively large compared to its star, in a proportion that scientists were not even sure it was possible to find in the universe. This discovery could represent a challenge to our current theories about planetary formation.
The planet is in the constellation of Columba, 600 light years away from Earth, and has 20% less mass than Jupiter. As it is very close to its star, the year lasts 2.6 days and the surface temperature reaches 530 ºC.