Black Science

If you had a chance to turn any army in the world into the one you picked, which troops would be there?

Astronomers have discovered an iron sky...
..on the dark side of the hot Jupiter WASP-121b, 850 light-years away from us.

The giant is about 18% larger than our Jupiter; it orbits a star about 1/4 the size of our Sun. It's so close to the star that a year lasts 1.27 Earth days there. The planet is in tidal locking, and the temperature on the ever-day side reaches 2,300-2,500 °C. This is enough to melt many metals and even to vaporise them.

According to the results of two years of infrared Hubble observations, the ever-night side of the planet is more than 2,000 °C cooler. So, clouds and rain condense out of iron and aluminium oxide. It's corundum which can be rubies or sapphires.

In a way, we can say that scientists have found a planet with sapphire-ruby precipitation.

Source: Diurnal variations in the stratosphere of the ultrahot giant exoplanet WASP-121b — Nature Astronomy.

How many spots have you spotted?

If more than four, then your eyesight is better than that of the entomologist who came up with it's name — Four-spotted Chaser.