The sky is blue. The oceans are blue. While science can explain them both, the reasons for each are entirely different. — If you’ve ever been curious about the world you live in, you’ve probably wondered why the sky is blue. The incorrect answers that people often give in response include: that sunlight has a blue tint, that oxygen itself is a blue-colored gas, or that the sky reflects the oceans.

At four million solar masses, the Milky Way’s supermassive black hole is quite small for a galaxy its size. Did we lose the original? — At the heart of the Milky Way, a supermassive behemoth lurks. Formed over billions of years from a combination of merging black holes and the infalling matter that grows them, there now sits a mammoth black hole that weighs in at four million solar masses. It’s the largest black hole…

Time isn’t the same for everyone, even on Earth. Flying around the world gave Einstein the ultimate test. No one is immune from relativity. — In 1905, our conception of how the Universe changed forever when Einstein put forth his special theory of relativity. Prior to Einstein, scientists were able to describe every “point” in the Universe with the use of just four coordinates: three spatial positions for each of the three dimensions, plus a…

The idea of black holes have been around for over 200 years. Today, we’re seeing them in previously unimaginable ways. — For centuries, black holes were merely theoretically speculative ideas.

After years of analysis, the Event Horizon Telescope team has finally revealed what the Milky Way’s central black hole looks like. — The moment has finally arrived. Back in 2015, the Event Horizon Telescope collaboration formed, with the goal of using an array of radio telescopes located all around the world to directly image the event horizon of a black hole for the first time. …

In Sun-like stars, hydrogen gets fused into helium. In the Big Bang, hydrogen fusion also makes helium. But they aren’t close to the same. — In all the Universe, there’s arguably no reaction more important than nuclear fusion. Without it, hydrogen would be the only element in the Universe. Without it, there would be no shining stars throughout the Universe. Without it, planets wouldn’t be possible, and there would be no instances of life in…

Drop sodium in water, and a violent, even explosive reaction will occur. But quantum physics is needed to explain why. — It’s a little bit paradoxical: when we encounter something unexpected for the first time, we wonder why it happens that way. …

The Standard Model may or may not be in trouble, but particle physics definitely needs saving. Here’s what the new LHC can do. — Everyone in the physics community agrees: particle physics is in trouble. Yet, depending on whom you ask, you’re likely to hear that the root of the trouble originates in a few very different places. Particle physics is in trouble because there are now so many cracks in the Standard Model…

Everything that gets heated up has to, somehow, radiate that energy away. Here’s what we see when that happens in the Universe. — On average, today’s Universe is an extremely cold place.