universe

Stephenson 2-18 is a star so large that if it replaced the Sun, its surface would engulf Saturn's orbit. The black hole at the center of galaxy TON 618 contains 66 billion solar masses — more than the combined mass of every star in the Milky Way. The Hercules-Corona Borealis Great Wall spans 10 billion light-years, a structure so enormous that its very existence challenges the standard cosmological model. Mass in the universe operates at scales that have no human analogy, and each record reveals a different physical constraint — or its violation.

The observable universe is 93 billion light-years across, but the real universe is far bigger — possibly infinite. Here's how we know.

The Big Bang explained: evidence from Hubble's law, the CMB, and primordial element abundances, plus the timeline of cosmic history and the universe's fate.

The Moon's origin is reconstructed from rocks, its interior, and orbital models. A giant impact leads the explanation, but the precise scenario is uncertain.

Mars is the most explored planet beyond Earth: home to the largest volcano in the solar system, a canyon system thousands of kilometers long, and clear evidence that it once hosted flowing water. Here is what science has revealed.

About 4.57 billion years ago, a cloud of gas and dust collapsed under its own gravity. Out of the disk it left behind came the Sun, eight planets, hundreds of moons, and the debris belts of our cosmic neighborhood.

For two centuries, Newton's gravity was the gold standard. Then Einstein showed that gravity isn't a force at all — it's the curvature of spacetime itself. Here's what that actually means, and how it has been tested.

Pulsars produce repeating signals as neutron stars rotate. Their timing helps researchers study binary orbits and search for gravitational-wave backgrounds.

December 1995: Hubble stared at one blank patch of sky for about 10 days and found roughly 3,000 galaxies, changing how astronomers count the universe.

July 2022: JWST's first images revealed galaxies 13.6 billion light-years distant, formed just 100 million years after the Big Bang, reshaping cosmology.

The universe has been expanding for 13.8 billion years, and dark energy is currently accelerating that expansion. If it suddenly reversed and the universe began contracting, we would be heading toward a 'Big Crunch' — but the change would be too slow for any individual to notice.

Zoom out far enough and galaxies stop looking scattered. They trace a web of filaments, walls, clusters, and voids that spans hundreds of millions of light-years. Here is how it formed, how it was mapped, and what it is made of.