A strange planet was discovered in May 2020, 855 light-years from Earth in the Hercules constellation, that is five times larger than Jupiter and has temperatures so hot that the molecules on the planet are torn apart into atoms.
The planet is called TOI-2109b, and it’s known as an “ultrahot Jupiter,” which means it is a gas giant that orbits its star very closely and has extremely high surface temperatures.
TOI-2109b has some amazing extremes. The daytime surface temperature is about 3,500 Kelvin or about 6,000 degrees Fahrenheit (3,316 degrees Celsius). That’s the temperature equivalent of a small star and why molecules on the planet are ripped into atoms. It also has one of the shortest orbits of a planet around its star at only 16 hours. By comparison, Jupiter, also a gas giant, has an orbit around the Sun of 12 years.
The tight orbit of TOI-2109b happens because the planet is only 1.5 million miles away from its star. Mercury, the innermost planet in our solar system, is around 36 million miles away from the Sun. The planet’s star is also massive, about 50 percent bigger than the Sun, and TOI-2209b is spiraling into it at a rate that is faster than any other “ultrahot Jupiter” observed, 10 to 750 milliseconds per year.
It’s believed that the planet is tidally locked to its star, meaning that the same side faces its star all the time. This is similar to how our Moon has the same rotational period as Earth and why we see only one side of the moon from Earth all the time.
TOI-2209b was discovered in 2020 by NASA’s Transiting Exoplanet Survey Satellite (TESS) and observed for a year before confirming the existence of the new ultrahot Jupiter. About 400 hot Jupiters have been discovered, and scientists are still unsure how these giant “hell” planets form.