Scientists have discovered the strongest evidence to date for a stratosphere on a planet outside our solar system, or exoplanet. A stratosphere is a layer of atmosphere in which temperature increases with higher altitudes. “This result is exciting because it shows that a common trait of most of the atmospheres in our solar system —…

For the supermassive black hole at the center of our Milky Way galaxy, it’s been a long time between dinners. NASA’s Hubble Space Telescope has found that the black hole ate its last big meal about 6 million years ago, when it consumed a large clump of infalling gas. After the meal, the engorged black…