Astronomers discover hot, dense planet with eight-hour year

In a new study, published in the journal Nature, the researchers show that the planet, which is 31 light years from Earth, is one of the lightest among the nearly 5,000 exoplanets (planets outside our own solar system) that are known today, with half the mass of Earth. It has a diameter of just over 9,000 kilometers—slightly larger than Mars.