In honor of the recent discovery of the hottest planet we know of, let's look at some of the most extreme planets that astronomers have discovered so far.
The oldest planet that we know of is a whopping 12.7 billion years old. In comparison, Earth is a relatively young 4.543 billion years old. Also, our universe is about 13.8 billion years old. The planet, PSR B1620-26 b, therefore formed just a billion years after the formation of the universe. This indicates that it's possible that other planets may have formed relatively early, which means that there may be a lot of planets that we haven't discovered yet.
Its early birth also means that PSR B1620-26 b cannot support life, since it doesn't have the necessary elements.
If the oldest planet is billions of years old, the youngest planet is just two million years old—basically a baby by cosmological standards. The planet V830 Tauri b is an exoplanet that orbits the star V830 Tauri. This star has the same mass as our sun but has twice the radius, which indicates that the star has yet to mature. Eventually, V830 Tauri will contract to its final shape.
The baby planet V830 Tauri b is also probably still growing. As of now, it has 77% the mass of Jupiter, but may acquire more mass by colliding with other planetary bodies.
KELT-9b may be one of the most extreme planets we know of today. This planet is so hot that it's actually hotter than most stars. In spite of this, however, KELT-9b is still a planet because its warmth comes from an external source. The planet orbits quite close to its star, which accounts for the high surface temperatures.
Surface temperatures on KELT-9b can rise to up to 4,300ºC, and the planet is just marginally cooler than our sun. Water, carbon dioxide, and methane also can't exist on the planet because the molecules will simply evaporate in the heat.
11 years ago, OGLE-2005-BLG-390Lb was the most Earth-like planet we knew of. Now, it holds the distinction of being the coldest. The planet orbits the star OGLE-2005-BLG-390L, a relatively cool red dwarf. The planet isn't all that distant from its host star, but the star itself isn't that hot. Thus, OGLE-2005-BLG-390Lb has surface temperatures as low as -220ºC.
Though the planet is Earth-like, it may actually resemble Pluto more. Substances like water, nitrogen, methane, and ammonia can only exist in frozen form on OGLE-2005-BLG-390Lb. Thus, the planet can't sustain an atmosphere and probably can't support life.
One of the planets in our own solar system can boast of a place on this list. Venus, our famously beautiful neighbor, actually experiences the most violent storms in any planet that we know of. In fact, the planet's atmosphere moves faster than the planet itself rotates. These winds can reach speeds up to 360 kilometers per hour—just as fast as hurricanes.
Venus is actually very dry and will probably kill any form of life that happens upon its surface. Its atmosphere is what makes Venus one of the most extreme planets that we know of today.
Get weekly science updates in your inbox!