Although the space between stars in our galaxy appears to be completely empty of matter, there exists a very dilute gas even in “empty” space. This interstellar (meaning “between the stars”) medium varies in density (the amount of matter within a certain volume). Typical densities in the interstellar medium are

2025年1月9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.

Europa’s surface is made of water ice and so it reflects 5.5 times the sunlight than our Moon does. Europa orbits Jupiter at about 417,000 miles (671,000 kilometers) from the planet, which itself orbits the Sun at a distance of roughly 500 million miles (780 million kilometers), or 5.2 astronomical units (AU).

Our Sun belongs to the generation of stars created 4.6 billion years ago, when our galaxy was roughly half its present age. A cloud of interstellar gas, dust, and ices containing several generations of material collapsed to form the nebula from which the Sun and the rest of …

2024年10月24日 · In dark corners of the galaxy are worlds fit for creatures of the night. Explore the homes of Frankenstein’s monster, Dracula’s lair, the place where zombies roam, and more. Take a journey to these dark and sinister worlds

Despite its proximity to the Sun, Mercury is not the hottest planet in our solar system – that title belongs to nearby Venus, thanks to its dense atmosphere. But Mercury is the fastest planet, zipping around the Sun every 88 Earth days.

2025年1月9日 · Pluto was once our solar system's ninth planet, but has been reclassified as a dwarf planet. It's located in the Kuiper Belt.

outshine the entire galaxy the star was part of. Stars generate energy in their cores by nuclear fusion: four hydrogen nuclei fuse to create helium. Stars are so enormous (our sun has a mass almost a million times that of the Earth!) that the weight of a star’s outer layer presses down on the core, raising the density

Dark, cold, and whipped by supersonic winds, ice giant Neptune is the eighth and most distant planet in our solar system. More than 30 times as far from the Sun as Earth, Neptune is the only planet in our solar system not visible to the naked eye.

2010年10月31日 · And the answer, published online today in the Astronomical Journal, is this: The rings are behaving like a miniature version of our own Milky Way galaxy. This new insight, garnered from images of Saturn's most massive ring, the B ring, may answer another long-standing question: What causes the bewildering variety of structures seen throughout ...