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Universe Expansion
Astrophysicists once believed in a static Universe, containing only the Milky Way galaxy. Science definitively proved otherwise.
After more than two decades of precision measurements, we've now reached the "gold standard" for how the pieces don't fit.
A few years ago, the first dark matter-free galaxies were announced, and then immediately disputed. Now, there are too many to ignore.
Every December, the Geminid meteor shower reaches its peak. Its 2021 show will be spectacular, but only if you do it right.
Our Solar System's outer reaches, and what's in them, was predicted long before the first Oort Cloud object was ever discovered.
Previously, only the brightest and most active galaxies could pierce the obscuring wall of cosmic dust. At last, normal galaxies break through.
The stars, planets, and many moons are extremely round. Why don't they take other shapes?
The majority of the matter in our Universe isn't made of any of the particles in the Standard Model. Could the axion save the day?
We haven't seen a partial eclipse lasting this long since 1440, and won't again until 2669. North America is perfectly positioned for 2021's.
Although most of the Universe's mass is dark matter, which gravitates just as well as normal matter, it still can't make black holes.
The latest gravitational wave data from LIGO and Virgo finally shows us the truth: there are no "gaps" in the masses of black holes.
There are over 100 known elements in the periodic table. These 8 ways of making them account for every one.
There's a big difference between the notions of 'false vacuum' and 'true vacuum' states. Here's why we don't want to live in the former.
The highest-energy particles of all come from space, not human-made colliders. When it comes to the most energetic particle collisions of all, you might think that the Large Hadron Collider […]
Whatever’s lurking out there, it isn’t all, or even mostly, normal matter. When it comes to the Universe, it’s only natural to wonder what, exactly, it is that makes everything up. […]
“Hubble’s Law” is only an approximation, and breaks down when we need it most. From anywhere in the Universe, you can choose to look out at any other galaxy that’s present. […]
It happened more than once, and needed to. Here’s why. If there’s one thing you can be certain about when it comes to outer space, it’s that it’s transparent, not opaque, […]
If it wasn’t a singularity, how small could it have been? Today, when you look out in any direction as far as the laws of physics allow us to see, the […]
Both made monumental contributions that were far ahead of their time. It’s hard to believe, but the idea that the Universe was dominated not by normal matter but rather by dark […]
Hubble, our greatest space-based observatory today, is just the beginning. The Hubble Space Telescope has been astronomy’s most revolutionary observatory in history. The stars and galaxies we see today didn’t […]
Galaxies can have regions both hotter and colder than the background radiation of the Universe. When we talk about the depths of space, we get this picture in our heads […]
We’ve already observed three cases where it’s happened. When you look at an object in space, it’s pretty easy to tell if it’s a star or a planet. Stars are […]
When you mix science with speculation, you get speculation. But the underlying science is still real. Whenever you hear the phrase, “it’s just a theory,” it should trigger alarm bells in […]
It could evolve, strengthen, decay, or not be alone. Our known Universe contains matter, radiation, and dark energy. While matter (both normal and dark) and radiation become less dense as […]
The raw ingredients just weren’t there. Thankfully, their predecessors were. Here on Earth, our planet practically overflows with life. After more than 4 billion years, life has spread to practically […]
It peaks the nights of August 11–13, but it’s no longer the year’s most reliable meteor shower. Every year, beginning in mid-July, planet Earth commences passing through an enormous debris […]
Even a small merger can trigger so much more than we realize. Practically every galaxy in the Universe has a supermassive black hole at their core. Ranging from millions to many […]
If we succeed in contacting them, will that seal humanity’s doom? One of the most wondrous questions of all concerns our place in the Universe. After 13.8 billion years of […]
And, if we have one, how close are we to it? No matter which direction we look in, or how far away our telescopes and instruments are capable of seeing, the […]
Only the best physical theories outlast the minds that invented them. Throughout the 20th century, a number of discoveries revolutionized our Universe. The discovery of the interior structure of atoms as […]