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Universe Expansion
The fundamental building blocks of reality are indivisible: quanta that cannot be split or divided. Our understanding remains incomplete.
Long after the last star burns out, the Universe will experience its end state: a heat death. Will everything prior then be meaningless?
The Universe is expanding, the expansion is accelerating, and some galaxies even recede faster-than-light. Can we see a change in real time?
Before Sun-like stars die, they transition from AGB red giants into preplanetary nebulae. Here's how Hubble sees the famous Egg Nebula.
Here in our modern Universe, it's cosmic dust that forms planets, complex molecules, and enables life. But how did the Universe create it?
13.8 billion years have passed since the Big Bang, but many stars will survive for longer than that. What's the longest-lived a star can be?
Many collaborations have used JWST to take deep-field images: some wider and some deeper than others. Here's how it can surpass them all.
The Universe formed stars, galaxies, and even galaxy clusters extremely early on in our cosmos. This new marvel is one more JWST surprise.
At the upper limits of what's energetically possible, cosmic rays still persist. What happens if a human gets hit by the most energetic one?
Our great hope is that today's indirect, astrophysical evidence will someday lead to successful direct detection. What if that's impossible?
Our view of the world, the Universe, and ourselves can change with just one glimpse of what's out there. It's happened many times before.
Outer space begins just over 100 kilometers up, but what we can see extends for billions of light-years. Here's what all of it looks like.
Even in an expanding Universe, we expect both redshifted and blueshifted galaxies. But nearly every one we see is redshifted. Here's why.
With unprecedented resolution, wavelength sensitivity, and light-gathering power, JWST reveals our cosmos like no other observatory ever.
Gravitational lenses arise when foreground masses and background light sources properly align. Einstein rings are rare, but crosses abound.
It's not about particle-antiparticle pairs falling into or escaping from a black hole. A deeper explanation alters our view of reality.
The VENUS survey isn't about planets at all, but about finding multiply-lensed supernovae. The ambition? To save the expanding Universe.
Back in 1604, Johannes Kepler discovered the Milky Way's last naked-eye supernova. Here's how NASA's Chandra sees it over the 21st century.
The seeds of cosmic structure that were planted back during the Big Bang grew into the cosmic web we see today. What is it telling us?
When objects are gravitationally bound, they cannot escape from one another's influence. How does that work within the expanding Universe?
Even the youngest galaxies are often dust-rich, even with very low levels of heavy elements. Nearby dwarf galaxy Sextans A explains why.
Astronomers have found starless gas clouds before, but Cloud 9 might be the most pristine one of all, with big lessons for cosmic history.
In a galaxy less than 300 million years after the Big Bang, oxygen's presence abounds. That's expected; its absence would truly be profound.
In general relativity, matter and energy curve spacetime, which we experience as gravity. Why can't there be an "antigravity" force?
The very word "quantum" makes people's imaginations run wild. But chances are you've fallen for at least one of these myths.
There will always be "wolf-criers" whose claims wither under scrutiny. But aliens are certainly out there, if science dares to find them.
If you can identify a foreground star, the spike patterns are a dead giveaway as to whether it's a JWST image or any other observatory.
Perhaps the most remarkable fact about the Universe is simply that it, and everything in it, exists. But what's the reason why?
The highest-energy particles could be a sign of new, unexpected physics. But the simplest, most mundane explanation is particularly iron-ic.
While humanity has been skywatching since ancient times, much of our cosmic understanding has come about only recently. Very recently.