Not so long ago, scientists discovered the hottest planet in the entire history of observations - with surface temperatures exceeding that of even some stars. As the search continues for planets outside our own solar system, we find many other worlds with extreme features. And ongoing exploration of our own solar system is also revealing some rather strange representatives. Here are seven strange celestial objects with unusual and outstanding features.
Hottest
How hot a planet will be depends primarily on how close it is to its parent star - and how hot that very star is. In our own solar system, Mercury is considered the closest planet to the sun, at an average distance of 57,910,000 kilometers. The surface temperature during the day reaches 430 degrees Celsius, while on the sun's surface this value is 5500 degrees.
But stars more massive than our sun will be noticeably hotter. HD 195689, also known as KELT-9, is 2.5 times more massive than the sun and has a surface temperature of 10,000 degrees. Its planet, KELT-9b, is much closer to its parent star than Mercury is to the sun.
Although we cannot measure the exact distance from afar, the planet revolves around its star every 1.5 days (Mercury completes its orbit in 88 days). The planet's surface temperatures are an astounding 4,300 degrees, which is hotter than the surface of many less than solar masses. The solid planet Mercury would turn into a drop of lava at this temperature. But KELT-9b, however, is a Jupiter-type gas giant.
Promotional video:
Coldest
At just 50 degrees above absolute zero - -223 degrees Celsius - OGLE-2005-BLG-390Lb deserves the title of the coldest planet. About 5.5 times more massive than Earth, this planet is also considered solid. It is not too far from its parent star - much like between Mars and Jupiter in our solar system - but its star is low in mass and is a cool red dwarf.
This planet is often referred to as Hoth (after the ice planet in Star Wars). But, unlike a fictional planet, a real ice giant cannot hold much of the atmosphere (and neither does life). Because most of its gases will be frozen as snow on the surface.
The biggest
If a planet can be as hot as a star, what is the difference between the two? The stars are so much more massive than the planets that the processes of thermonuclear fusion occur in their depths as a result of the action of powerful gravitational forces in the core. Ordinary stars like our sun burn hydrogen into helium. But there is also a type of star called brown dwarf stars that are large enough to trigger fusion processes, but not large enough to support them. The planet DENIS-P J082303.1-491201 b with the same unpronounceable alias 2MASS J08230313-4912012 b is 28.5 times more massive than Jupiter - and this makes it the most massive planet on the NASA exoplanet archive. It is so massive that there is debate over whether it can be called a planet (then it will be a gas giant like Jupiter) or whether it is better to classify it as a brown dwarf star. Ironically, its parent star is also a brown dwarf star.
The smallest
Kepler-37b is slightly larger than our Moon and slightly smaller than Mercury, and is the smallest exoplanet found. This solid world is closer to its parent star than Mercury is to the sun. This means that the planet is too hot to support liquid water and life on the surface.
The oldest
PRS B1620-26 b is 12.7 billion years old and is considered the oldest known planet. This gas giant with 2.5 times the mass of Jupiter seems to have existed forever. Our Universe is only a billion years older than this planet.
PSR B1620-26 b has two parent stars orbiting each other - and appears to have outlived both of them. Only a neutron star and a white dwarf remained after the star burned out and exploded in a supernova. But because it formed so early in the history of the universe, it sorely lacked the heavy elements like carbon and oxygen (which formed later), which are necessary for the evolution of life.
The youngest
The planetary system V830 Tauri is only 2 million years old. The parent star in the system has the same mass as our sun, but the radius is twice as large, which means that it has not yet fully compressed into its final shape. The planet - a gas giant with three-quarters of Jupiter's mass - is also growing. It gains mass by colliding with other planetary bodies such as asteroids in its path, making it an unsafe place.
With the worst weather
Since exoplanets are too far away from us for us to observe any weather conditions, we must pay attention to our solar system. If you've seen the giant swirling hurricanes captured by the Juno spacecraft flying over the poles of Jupiter, the largest planet in our solar system would certainly be a good contender. However, Venus will be the winner. A planet the size of Earth, shrouded in clouds of sulfuric acid.
The atmosphere moves around this planet much faster than the planet orbits. The wind speed reaches 360 km / h. Cyclones hovered over each pole. The planet's atmosphere is nearly 100 times denser than Earth, and is 95% carbon dioxide. The growing greenhouse effect is generating hellish temperatures of 460 degrees on the surface - even hotter than on Mercury.
ILYA KHEL