In Depth The Sun is a 4.5 billion-year-old yellow dwarf star – a hot glowing ball of hydrogen and helium – at the center of our solar system. It’s about 93 million miles (150 million kilometers) from Earth and …

2025年10月21日 · The Sun is the star at the heart of our solar system. Its gravity holds the solar system together, keeping everything – from the biggest planets to the smallest bits of debris – in its orbit.

The planetary system we call home is located in an outer spiral arm of the Milky Way galaxy. Our solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, …

2025年10月21日 · Mars is the fourth planet from the Sun, and the seventh largest. It’s the only planet we know of inhabited entirely by robots.

Because Earth is moving as well – rotating on its axis as it orbits the Sun – from our perspective, the Moon appears to orbit us every 29 days. Structure Earth's Moon has a core, mantle, and crust. The …

Size and Distance The Kuiper Belt is one of the largest structures in our solar system – others being the Oort Cloud, the heliosphere, and the magnetosphere of Jupiter. Its overall shape is like a puffed-up …

2025年10月21日 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

2026年3月11日 · Jupiter is the fifth planet from the Sun, and the largest in the solar system – more than twice as massive as the other planets combined.

The Kuiper Belt should not be confused with the Oort Cloud, which is a thousand times more distant. In 1950, astronomer Jan Oort proposed that certain comets come from a vast, extremely distant …

Titan’s atmospheric nitrogen ratio suggests the moon’s building blocks formed early in the solar system's history, in the same cold disk of gas and dust that formed the Sun (called the protosolar nebula), …