An international team of astronomers has discovered a hot planet draped in clouds of metal and glass that reflects up to 80 percent of light back into space.
Each planet has its own albedo (reflectivity) value, and the higher it is, the more starlight the planet will reflect back into space. For example, the geometric albedo of the Earth is only about 36 percent, so from space our planet looks, of course, not too dark, but not shiny. The leader in albedo among the planets in the solar system is Venus: it has an albedo of about 70 percent because of its dense clouds.
Now an international team of astronomers has found a celestial body 260 light-years from our system, which reflects 80 percent of the light of the parent star. If such an exoplanet - known as LTT9779b - existed in the solar system, it would be comparable in brightness to Venus, the brightest object in the night sky, aside from the moon.
LTT9779b is five times larger than Earth and the size of Neptune, but completes a full revolution around its parent star in just 19 hours. Because it is so close to the star, the temperature on the illuminated side of the planet is 2,000 degrees Celsius. So it's too hot for water vapor clouds to form, but LTT9779b does have clouds. Only they do not consist of water, but of silicates and metals, including, for example, titanium.
However, this planet is interesting not only for its brilliance, but also for its location. Although LTT9779b is a gas giant, it is significantly smaller than other giants found so close to stars. It appears that its atmosphere should have long ago vaporized, leaving behind only a bare, rocky core. This would explain the presence of refractory and relatively heavy elements in the clouds. Perhaps the blowing away of the gas shell LTT9779b is just prevented by shiny clouds that act as a protective mirror.
According to scientists who published the study in the journal Astronomy & Astrophysics, the discovery of such a planet can be considered an important milestone in the history of the study of exoplanets. If earlier, the near regions around the stars were nicknamed "Neptune deserts" and the detection in them not large gas giants were considered impossible, but now the universe has proved to us that this is not the case. At least a population of "Saturns stripped down to Neptunes" is possible in such zones.
The albedo of a planet plays an extremely large role in its habitability. For example, if Venus had a gas shell like Earth's, then with its high albedo it could be habitable, even though it receives much more energy from the Sun than we do.
So while Venus is technically too close to its star to be categorized as habitable, de facto life could exist on it. If exoplanets - as seen in the example of LTT9779b - have even higher albedo values, it is hard to rule out that there are habitable worlds among the formally too close to their stars.
