One of the most interesting aspects of exoplanetary science is the possibility of studying worlds that are not present in our Solar System (at least, not today). Some of these exoplanets possess such extreme properties that they are of great scientific interest. This is certainly the case for the Ultra-Hot Jupiter KELT-9b. It is a gas giant with a mass
Hot Jupiters are gaseous planets orbiting very close to their stars, typically closer than 0.1 Astronomical Units (the average distance between Earth and Sun), and with very short orbital periods of days or even hours. An extreme sub-class of these planets are the ultra-Hot Jupiters. These planets are tidally-locked to their stars (which means that they show always the same