In the crowded early Solar System, young planets frequently collided and reshaped each other. But Mercury stood out. It formed unusually close to the Sun. Mercury’s days are longer than its years. It ...

Rather than slowly condensing over millions of years, the first building blocks of Earth and other planets may have formed ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

An interstellar object has been spotted zipping through our solar system, and amateur and professional astronomers around the world are now racing to train their telescopes in its direction, allowing ...