The same happens when they're annihilated. The temperature increase is due to how much dark matter enters the planet, and the energy that's input can also accelerate the planet's rotation period.

Using the Keck Observatory, astronomers measured the spins of dozens of giant planets and brown dwarfs orbiting distant stars. They found that giant planets can spin faster than much more massive ...

Venus takes about 243 Earth days to complete a single rotation, and it does so in the opposite direction from nearly every other planet orbiting the Sun. That backward spin means the Sun appears to ...

In a blazing orbit—in both definitions of the word—of somewhere between one and 10 days tightly wound around its host star, hot Jupiters are some of ...