Illustration comparing the planets of the Solar System and the Sun on the same scale. The planets are shown to scale relative to each other but their distances are not. From left to right the bodies ...

Astronomers have spotted an intriguing cluster of objects in the Kuiper belt, the enormous, donut-shaped region of icy objects beyond the orbit of Neptune. This latest “inner kernel” was identified by ...

Earth and Mars were formed from material that largely originated in the inner Solar System; only a few percent of the building blocks of these two planets originated beyond Jupiter’s orbit. A group of ...