One astronomical unit (or AU) is the distance from the Sun to Earth, or about 93 million miles (150 million kilometers). The Oort Cloud is the boundary of the Sun's gravitational influence, where …

Oct 21, 2025 · 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.

But the Sun is a dynamic star, constantly changing and sending energy out into space. The science of studying the Sun and its influence throughout the solar system is called heliophysics. The Sun is the …

During a "full moon," the hemisphere of the Moon we can see from Earth is fully illuminated by the Sun. And a "new moon" occurs when the far side of the Moon has full sunlight, and the side facing us is …

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

Sep 3, 2025 · Jupiter Jupiter is the fifth planet from the Sun, and the largest in the solar system, by far — more than twice as massive as the other planets combined.

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

Oct 21, 2025 · Solar System Our Solar System Sun Kuiper Belt Oort Cloud Beyond Our Solar System Eclipses

In March 2004, a team of astronomers announced the discovery of a planet-like transneptunian object orbiting the Sun at an extreme distance, in one of the coldest known regions of our solar system.

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