Universe Expansion

Universe Expansion

black hole hit Earth
The odds are slim, but the consequences would be devastating. Here's what would happen, plus how to avoid it.
symmetric
If the electromagnetic and weak forces unify to make the electroweak force, maybe, at even higher energies, something even greater happens?
A rocket launching into space.
Nearly 200 orbital launches are scheduled for 2022.
With 1550 distinct type Ia supernovae measured across ~10 billion years of cosmic time, the Pantheon+ data set reveals our Universe.
greatest ideas in science
The ten greatest ideas in science form the bedrock of modern biology, chemistry, and physics. Everyone should be familiar with them.
space expanding
Yes, the Universe is expanding, but you might wonder, "How fast is it expanding?"
average star
Please stop calling our Sun an "average star." It is philosophically dubious and astronomically incorrect.
asymmetry
The Universe has asymmetries, but that's a good thing. Imperfections are essential for the existence of stars and even life itself.
There really might be extraterrestrials out there, attempting to make contact. Here's how science, not fiction, is attempting to find them.
parallel universe
In scientific theories, the Multiverse appears as a bug rather than as a feature. We should squash it.
how many stars
There are ~400 billion stars in the Milky Way, and ~2 trillion galaxies in the visible Universe. But what if we aren't typical?
CMB cold spot
The Universe is supposed to be the same everywhere and in all directions. So what's that giant "cold spot" doing out there?
m81 group
Just 12 million light-years away, the galaxies Messier 81 and 82 offer a nearby preview of the Milky Way-Andromeda merger.
travel straight line
Is the Universe finite or infinite? Does it go on forever or loop back on itself? Here's what would happen if you traveled forever.
big bang
There are an estimated two trillion galaxies within the observable Universe. Most are already unreachable, and the situation only gets worse.
James Webb Hubble
Hubble's deepest views of space revealed fewer than 10% of the Universe's galaxies. James Webb will change that forever.
super-Earth
In terms of the planets we've discovered, super-Earths are by far the most common. What does that mean for the Universe?
Alexander Friedmann
It is time to give the Russian cosmologist the credit he deserves.
A color-enhanced image of Jupiter using data from the JunoCam camera..
With a new telescope on the horizon, we reflect on the best pictures of space that came before.
astrophysics ALMA
If you want to understand what the Universe is, how it began, evolved, and will eventually end, astrophysics is the only way to go.
quantum gravity
At a fundamental level, nobody knows whether gravity is truly quantum in nature. A novel experiment strongly hints that it is.
how many planets
In 1990, we only knew of the ones in our Solar System. Today, we know of thousands, and that's just the tip of the iceberg.
universe temperature
We frequently say it's 2.725 K: from the light left over all the way from the Big Bang. But that's not all that's in the Universe.
redshift distance raisin bread
There are two fundamentally different ways of measuring the Universe's expansion. They disagree. "Early dark energy" might save us.
supernova X-ray
The first supernova ever discovered through its X-rays has an enormously powerful engine at its core. It's unlike anything ever seen.
Earth move
The Solar System isn't a vortex, but rather the sum of all our great cosmic motions. Here's how we move through space.
Some stars burn through their fuel as expected, and die of natural causes. But others, instead, get murdered. Here's their story.
Friedmann equation
From before the Big Bang to the present day, the Universe goes through many eras. Dark energy heralds the final one.
primordial black holes
Known as primordial black holes, they could thoroughly change our Universe's history. But the evidence is strongly against them.