For hundreds of a millions of years, the universe existed in the dark ages—an epoch when only primordial gasses existed. Then, a period of reionization, cleared away this foggy existence an introduced ...

The constancy of the speed of light is a pillar of modern physics, but questions persist about its absolute universality.

The universe's expansion means its size is bigger than its age suggests. The universe's expansion doesn't have a speed limit like objects within it. Distant galaxies move away from us as space itself ...

Light speed would allow instant trips across Earth and minutes to reach the Sun, but even at 300,000 km/s the expanding ...

Over billions of years, the universe's stars and galaxies shined their light into space, leaving behind an imperceptibly faint night light known as the cosmic optical background. NASA's New Horizons ...

Astronomers have discovered what could be the largest black hole ever detected. With a mass of 36 billion times that of our Sun, its gravity is so powerful that it bends the light of an entire galaxy ...

My telescope, set up for astrophotography in my light-polluted San Diego backyard, was pointed at a galaxy unfathomably far from Earth. My wife, Cristina, walked up just as the first space photo ...

Banner image: Artist's depiction of the New Horizons spacecraft billions of miles from Earth. (Credit: NASA, APL, SwRI, Serge Brunier/ESO, Marc Postman/STScI, Dan Durda) Scientists have traveled to ...

Astronomers have discovered a vast tendril of hot gas linking four galaxy clusters and stretching out for 23 million light-years, 230 times the length of our galaxy. With 10 times the mass of the ...

Here is a thought experiment for you: imagine shining a powerful laser at the moon, the beam cutting through space until it lands on its dusty grey surface. Now flick the laser so the spot of light ...

This story is part of our Cosmic Perspective series, in which we confront the staggering vastness of the cosmos and our place in it. Read the rest of the series here. In a sense, we are at the centre ...

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