For some years, scientists have debated the existence of an unseen planet at least five times the mass of Earth in the outer reaches of the Solar System. Now, the hypothesis has been dealt a blow ...

Each of the outer solar system's giant planets is accompanied by ... space along fissures in its southern hemisphere — a sure sign of liquid water lurking just beneath the moon's thin, icy ...

The location of the solar system's outer boundary is a point of contention among astronomers. There are three possible candidates, which "all have merit." But which one is best? When you purchase ...

So exactly how many solar system moons have we found? The answer, it turns out, depends on your definition of a moon. But this is likely just "the tip of the iceberg," Edward Ashton, an astronomer ...

The formation of the solar system is a challenging puzzle for modern astronomy and a terrific tale of extreme forces operating over immense timescales. Let's dig in. Our solar system: A photo tour ...

THE question of the origin of the solar system is one that has been a source of speculation for over a hundred years; but, in spite of the attention that has been devoted to it, no really ...

Lucy launched in 2021 to Jupiter’s Trojan asteroids. Solar Orbiter studies the sun and its poles. Parker Solar Probe skims the edge of our star. STEREO A and STEREO B track solar storms.