Space has a knack for bending our sense of scale. The Moon feels close enough to touch—after all, we see its craters with nothing but our eyes. Yet, that 238,855-mile gap between Earth and its lunar ...

In the cold, distant reaches of the Solar System, far beyond Pluto, astronomers have just identified what could be a new dwarf planet. It's called 2017 OF 201, a rock that appears to be some 700 ...