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Some constants, like the speed of light, exist with no underlying explanation. How many "fundamental constants" does our Universe require?

Hubble showed us what our modern day Universe looks like. JWST's big goal was to teach us how the Universe grew up. Here's where we are now.

All stars, eventually, run out of fuel and die. Given all the stars we can see and the vast distance to them, are any of them already dead?

IceCube just found an active galaxy in the nearby Universe, 47 million light-years away, through its neutrino emissions: a cosmic first.

In 1667, a core-collapse supernova happened right here in the Milky Way, invisible to all humans. ~350 years later, here's what JWST sees.

Human beings are tiny creatures compared to the 92 billion light-year wide observable Universe. How can we comprehend such large scales?

The hot Big Bang was an energetic, brilliantly luminous event. Today's Universe is alight with stars. But in between, the dark ages ruled.

In the largest star-forming region close to Earth, JWST found hundreds of planetary-mass objects. How do these free-floating planets form?

Photons come in every wavelength you can imagine. But one particular quantum transition makes light at precisely 21 cm, and it's magical.

Einstein's most famous equation is E = mc², which describes the rest mass energy inherent to particles. But motion matters for energy, too.

Within the next few decades, we may well have hard evidence for the existence of alien life on worlds light-years distant from Earth.

There's an extra source of massive "stuff" in our Universe beyond what gravitation and normal matter can explain. Could light be the answer?

Each of our three nearest stars might have an Earth-like planet in orbit around it. Here's what we'll learn when we finally observe it.

Contrary to common experience, not everything needs a medium to travel through. Overcoming that assumption removes the need for an aether.

Headlines have blared that quasar ticking confirms that time passed more slowly in the early Universe. That's not how any of this works.

Nothing lives forever, at least, not in the physical Universe. But relativity allows us to get closer than ever, from one perspective.

It’s like radar, but with light. Distributed acoustic sensing — DAS — picks up tremors from volcanoes, quaking ice and deep-sea faults, as well as traffic rumbles and whale calls.

The observable Universe is 92 billion light-years in diameter. These pictures put just how large that is in perspective.

JWST has seen more distant galaxies than any other observatory, ever. But many candidates for "most distant of all" are likely impostors.

There's the textbook answer, then there's the real answer.

The image you're seeing isn't a hole in the Universe, and the cosmic voids that do exist aren't hole-like at all.

Before we discovered gravitational waves, multi-messenger astronomy got its start with light and particles arriving from the same event.

"Imagination is more important than knowledge" is often taken to mean that your conceptions outweigh what's real. That's not what he said.

If you're a massless particle, you must always move at light speed. If you have mass, you must go slower. So why aren't any neutrinos slow?

Yes, dark energy is real. Yes, distant galaxies recede faster and faster as time goes on. But the expansion rate isn't accelerating at all.

The ESA's Gaia mission just broke the record for closest black hole by over 1,000 light-years. Is there an even closer one out there?

Although we still don't know the question, we know that the answer to life, the Universe, and everything is 42. Here are 5 possibilities.

Einstein's theory of general relativity introduced the concept of space having a shape. So, what is the shape of space?

The farther away they get, the smaller distant galaxies look. But only up to a point, and beyond that, they appear larger again. Here’s how.

With a finite 13.8 billion years having passed since the Big Bang, there's an edge to what we can see: the cosmic horizon. What's it like?