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Universe Expansion
From the tiniest subatomic scales to the grandest cosmic structures of all, everything that exists depends on two things: charge and mass.
The CMB gives us critical information about our cosmic past. But it doesn't give us everything, and galaxy mapping can fill in a key gap.
The full extent of the Andromeda galaxy, the nearest large galaxy to our own, has been entirely imaged with Hubble's exquisite cameras.
Dark matter doesn't absorb or emit light, but it gravitates. Instead of something exotic and novel, could it just be dark, normal matter?
Ring galaxies are rare, but we think we know how they form. A new, early-stage version, the Bullseye galaxy, provides a new testing ground.
Only 5% of the Universe is made of normal "stuff" like we are. Could there be dark matter or dark energy life, or even aliens, out there?
A young, nearby, massive star, whose protoplanetary disk appears perfectly edge-on, was just viewed by JWST, with staggering implications.
Seeking life beyond the Solar System, we first look to the closest star systems with Earth-like planets. Here's why that's not good enough.
There are only four super star clusters in all the Local Group: rarities today. Here's what the youngest, the just-discovered N79, shows us.
Here in our Universe, both normal and dark matter can be measured astrophysically. But only normal matter can collapse. Why is that?
First discovered in the mid-1960s, no cosmic signal has taught us more about the Universe, or spurred more controversy, than the CMB.
From LIGO, there weren't enough neutron star-neutron star mergers to account for our heavy elements. With a JWST surprise, maybe they can.
Life might be more common across the Universe than the "Hard Steps Model" suggests.
Matter is made up largely of atoms, where atomic nuclei can contain up to 100 protons or more. But how were the heaviest elements made?
Cosmic inflation, proposed back in 1980, is a theory that precedes and sets up the hot Big Bang. After thorough testing, is it still valid?
Scientists just viewed one of the tiniest, most isolated, lowest-mass galaxies ever found with JWST. Despite all odds, it's still growing.
The Ring Nebula, a bright, circular planetary nebula, is created by a dying Sun-like star. After centuries, we finally know its true shape.
Since mid-2022, JWST has been showing us how the Universe grows up, from planets to galaxies and more. So, what's its biggest find of all?
The discovery of ultra-bright, ultra-distant galaxies was JWST's first big surprise. They didn't "break the Universe," and now we know why.
Seven years ago, an outburst in a distant galaxy brightened and faded away. Afterward, a new supermassive black hole jet emerged, but how?
Here in our Universe, stars shine brightly, providing light and heat to planets, moons, and more. But some objects get even hotter, by far.
Most stars shine with properties, like brightness, that barely change at all with time. The ones that do vary help us unlock the Universe.
The electromagnetic force can be attractive, repulsive, or "bendy," but is always mediated by the photon. How does one particle do it all?
Many of us look at black holes as cosmic vacuum cleaners: sucking in everything in their vicinity. But it turns out they don't suck at all.
There's no upper limit to how massive galaxies or black holes can be, but the most massive known star is only ~260 solar masses. Here's why.
In the year 2000, physicists created a list of the ten most important unsolved problems in their field. 25 years later, here's where we are.
We see objects whose light only arrives just now. But we see them as they were in the past: when that now-arriving light was first emitted.
Our Universe isn't just expanding, the expansion is accelerating. Instead of dark energy, could a "lumpy" Universe be at fault?
Despite the Sun's high core temperatures, atomic nuclei repel each other too strongly to fuse together. Good thing for quantum physics!
On larger and larger scales, many of the same structures we see at small ones repeat themselves. Do we live in a fractal Universe?