If we know how big the observable Universe is, why can’t we figure out how big the unobservable part is? 13.8 billion years ago, the Big Bang occurred. The Universe was […]

In 1987, we detected neutrinos from another galaxy in a supernova. After a 30 year wait, we’ve found something even better. One of the great mysteries in science is determining not […]

Immediately after the Big Bang, the Universe was more energetic than ever. What was it like? When we look out at the Universe today, we see that it’s full of stars […]

The brightest galaxies of all neither have the most stars nor the biggest black holes. Here’s how to solve the mystery. With some 400 billion stars burning steadily, the Milky Way […]

Finding the ingredients for life is a very different prospect than finding the products of life. Perhaps the greatest quest in science today is to find life that originated beyond Earth. […]

There’s a halo of dark matter permeating every galaxy, and that means its particles pass through us, too. The Universe, despite all the planets, stars, gas, dust, galaxies, and more we […]

Forget the spectacular explosions we create here on Earth. The Universe outdoes us in every way imaginable. Forget mere chemical reactions; in space, matter-energy conversion creates unprecedentedly powerful explosive events. […]

Dark energy is pushing distant galaxies apart from one another at an increasing rate. If the Big Rip hypothesis is true, things will only get worse from here. One of the […]

Cosmic inflation is what happened before, and set up, the Big Bang. Here’s what it’s like to live in an inflating Universe. Our Universe today is full of matter and […]

Many hoped we could do without dark matter. On cosmic scales, the evidence has finally spoken. For over 40 years, scientists have argued over dark matter’s existence. The extended rotation curve […]

What’s going on at the smallest and largest scales of all? Let’s look to the absolute limits of physics. Have you ever wondered what’s out there in the Universe, on the […]

The Universe is expanding, but different techniques can’t agree on how fast. No matter what, something major has got to give. Look out at a distant galaxy, and you’ll see it […]

If you thought LIGO’s recent discoveries were profound and unusual, wait until you meet OJ 287. Recently, LIGO has revolutionized our knowledge of the Universe by discovering merging black holes. The […]

In the search for fundamental truths in our Universe, one of the biggest questions, “are space and time continuous or discrete,” remains unanswered. Throughout the history of science, one of […]

In 2015, Ed Witten, the greatest living string theorist, wrote a piece on why. Here’s the version for everyone. It’s one of the most brilliant, controversial and unproven ideas in […]

Even before we have the James Webb Space Telescope, a controversy over when the first stars formed is growing. As far back as our most powerful telescopes have ever looked, we’ve […]

If dark energy were stronger or weaker, everything would be pretty much the same. And that’s a puzzle. After the Big Bang, the Universe was full of matter and radiation. It […]

The ingredients for life are everywhere, but so far the only life we know of comes from Earth. Here’s how that might change. Ever since human beings first turned our eyes […]

One of the night sky’s most famous sights isn’t what it appears to be. Perhaps the most famous sight of a dying star is the Ring Nebula, known since 1779. The […]

Dark energy tells us that the Universe’s expansion is accelerating. Here’s what that means for our disappearing Universe. One of the biggest surprises for humanity about the Universe is that […]

In the search for the youngest planet in the Universe, astronomers may have accidentally stumbled upon something entirely new. Growing up is hard to do in the Universe. In the great […]

Here on Earth, all the right conditions occurred for intelligent life to come about, but the nearest aliens, if they’re on another world, are light years away. But it doesn’t […]

In 2015, the ultra-distant galaxy CR7 was measured to have hydrogen and helium, but no carbon or oxygen. With new ALMA observations, there’s carbon after all. As brilliant as our Universe’s […]

‘Luck’ is the wrong word. The Universe cooperated, but we gave ourselves the opportunity by being prepared. It was already 28 years ago that the Hubble Space Telescope was launched […]

We see matter, but not antimatter, in our Universe. Could black holes be the answer? One of the greatest cosmic puzzles in our entire Universe is why there’s so much more […]

Just one equation relates the expansion of space to all the matter and energy we have. If you know this, you can know the fate of the Universe. Last week, […]

The picture itself is breathtaking. But what we learn is truly eye-opening. Galaxy clusters, like the massive one captured here by Hubble, PLCK G004.5–19.5, impress not just for their looks, […]

In the far future, the last star burns out, stellar corpses get violently ejected, and galaxies accelerate away. And then the fun begins. For centuries, the biggest questions about our Universe […]

If it can stretch the Universe from the size of a subatomic particle to billions of light years in a fraction of a second, why doesn’t Einstein’s relativity forbid it? When […]

Among the general public, people compare it to the aether, phlogiston, or epicycles. Yet almost all astronomers are certain: dark matter and dark energy exist. Here’s why. If you go by […]