Gliese 436 b is a Neptune-sized exoplanet orbiting the red dwarf Gliese 436. It was the first hot Neptune discovered with certainty and was among the smallest-known transiting planets in mass and radius, until the much smaller Kepler exoplanet discoveries began circa 2010.This alien world is located approximately 30 light-years from Earth towards the constellation of Leo. And it is made of excruciatingly hot ice. Gliese 436 b is one of the closest known exoplanets at a distance of about 30 light years away from the Earth. This exoplanet is about the size of Neptune, and is a mere 2.5 million miles away from its respective star, Gliese 436. For reference, Mercury is a staggering 35 million miles from the sun. One 2020 study that analysed Kepler data calculated that the Milky Way could harbour as many as six billion Earth-like planets, while another estimated the number of potentially habitable planets in our galaxy at about 300 million. Gliese 436 b orbits very closely to a small, old sun. Its temperature is hot–very hot, reaching over 980° Fahrenheit, This temperature is significantly higher than would be expected if the planet were only heated by radiation from its star, which was prior to this measurement, estimated at 520 K. Whatever energy tidal effects deliver to the planet, it does not affect its temperature significantly. A greenhouse effect would result in a much greater temperature than the predicted 520–620 K. But when astrophysicists observed qualities of the planet, its makeup did not seem to make any logical sense. The planet has an orbital period of 2.6 Earth days and transits the star as viewed from Earth. It has a mass of 22.2 Earth masses and is roughly 55,000 km in diameter, giving it a mass and radius similar to the ice giant planets Uranus and Neptune in the Solar System. The planet was recorded to transit its star by an automatic process at NMSU on January 11, 2005, but this event went unheeded at the time. In 2007, Michael Gillon from Geneva University in Switzerland led a team that observed the transit, grazing the stellar disc relative to Earth. Transit observations led to the determination of its exact mass and radius, both of which are very similar to that of Neptune, making Gliese 436 b at that time the smallest known transiting extrasolar planet. The planet is about four thousand kilometers larger in diameter than Uranus and five thousand kilometers larger than Neptune and slightly more massive. Gliese 436b orbits at a distance of four million kilometers or one-fifteenth the average distance of Mercury from the Sun.

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