LTT 9779 b

LTT 9779 b, officially named Cuancoá, is a Neptune-sized planet orbiting the sunlike star LTT 9779, or Uúba. As of 2023, it has the highest-known albedo of any planet.

Characteristics
LTT 9779 b is one of the few known planets in the Neptunian desert. It is highly reflective, with an albedo of 0.8. This makes it the most reflective exoplanet discovered so far. It completes an orbit around LTT 9779 in less than a day, making temperatures on the day side soar to over 2,000 degrees Celsius. Global climate models of the planet indicate it has a very metal-rich atmosphere, with clouds made of silicate likely being present.

Being in the Neptunian desert, LTT 9779 b is a very rare class of planet, with few like it being known. It is estimated that only 1 in 200 Sun-like stars possess a planet with an orbital period of less than a day, and most of those are Hot Jupiters or rocky planets, with ultra-hot Neptune planets being rare. Because of this, LTT 9779 b has been extensively studied by many space telescopes including Hubble and James Webb.

Name
LTT 9779 b was officially named Cuancoá in 2022 by the International Astronomical Union, as part of the NameExoWorlds competition. Cuancoá is a word that refers to the morning star in the Uwa language. Cuancoá's star was named Uúba after the word for "star," "seed," and "eye" in the same language.