Most of the Moon’s effects on Earth are small and imperceptible. But for the grunion, it’s absolutely essential. Although it’s the closest astronomical body to Earth, the Moon is still […]

Not only can’t astronomers and planetary scientists agree, but the IAU made it worse for everyone. If you were alive in 2006, you likely remember a momentous event in astronomy: […]

When stars get ejected from galaxies within massive clusters, they go where the dark matter is. Dark matter is one of the greatest mysteries in the Universe, displaying its effects in […]

General Relativity has nothing to do with light or electromagnetism at all. So how to gravitational waves know to travel at the speed of light? There are two fundamental classes of […]

If you think nothing can move faster than light, check out this clever way to defeat that limit. Nothing can move faster than the speed of light. When Einstein set forth […]

Here are four separate ways you can prove it, even 50 years after-the-fact. 50 years ago, on July 20, 1969, humanity took our first footsteps on the surface of another […]

Discovered by NASA’s Chandra X-ray observatory, it’s powered by a supermassive black hole. 2019 marks 20 years of NASA’s Chandra, humanity’s most powerful X-ray observatory. Artist illustration of the Chandra X-ray […]

The summer solstice is the longest day of the year, but doesn’t have the earliest sunrise or the latest sunset. Here’s why. The length of a day on planet Earth might […]

It’s where Earth’s axial tilt with respect to the Sun is most extreme. Here are the consequences. Today is June 21st, 2019: the day of the solstice. Although there are […]

Some galaxies might not have any dark matter. Here’s why you should care. There are two assumptions that everyone makes about the Universe for extremely good reasons, but they might not […]

A vacuum cleaner is the wrong picture. Time to bust that myth. There are no classes of object in our Universe more extreme than black holes. With so much mass present […]

At the core of the largest star-forming region of the Local Group sits the biggest star we know of. Mass is the single most important astronomical property in determining the lives […]

Two independent techniques give precise but incompatible answers. Here’s how to resolve it. If you didn’t know anything about the Universe beyond our own galaxy, there are two different pathways you […]

An entire Universe of possibilities await stars like our own, even after they run out of fuel. One of the most profound rules in all the Universe is that nothing lasts […]

Has the mystery really been solved? Doubtful. The real science goes much deeper. For perhaps the last year or so, a small galaxy located not too far away has captivated the […]

There aren’t any holes in the Universe at all. What actually exists is far more interesting. Somewhere, far away, if you believe what you read, there’s a hole in the […]

If we could see in three dimensions instead of two, we’d never have thought otherwise. Perhaps the most famous sight of a dying star is the Ring Nebula, discovered in […]

13.8 billion years isn’t close to enough time, but if we wait long enough, even our Sun will become one. The Big Bang happened approximately 13.8 billion years ago, and it […]

The solar eclipse of May 29, 1919, was the nail in the coffin of a Newtonian Universe. On May 29, 1919, the world changed forever. For hundreds of years, Isaac […]

Everything on Earth is made of atoms and their building blocks. Without this one rule, they’d never make anything interesting. Take a look around you at everything on Earth. If […]

Imagine how different our understanding of the Universe would be if we saw nothing beyond the Milky Way. Our corner of the Universe was gifted with a plethora of bright, nearby […]

A 1060-hour amateur exposure of a nearby galaxy does what even Hubble couldn’t do. The Universe is full of astronomical wonders, but it’s up to humanity to observe and analyze them. […]

The world’s greatest observatory can go no further with its current instrument set. The Hubble Space Telescope has provided humanity with our deepest views of the Universe ever. It has […]

It’s made up of scores of telescopes at many different sites across the world. But it acts like one giant telescope. Here’s how. If you want to observe the Universe more […]

Our Sun will someday run out of fuel. Here’s what it will look like when that happens. The fate of our Sun is unambiguous, determined solely by its mass. If all […]

It might be the biggest conundrum facing cosmology today. But perhaps it’s not a controversy; it might be a clue. https://soundcloud.com/ethan-siegel-172073460/starts-with-a-bang-44-the-expanding-universe/ One of the biggest conundrums in the Universe surrounds the […]

Our outer Solar System, from Jupiter to Neptune, isn’t unique after all. In the early 1990s, scientists began detecting the first planets orbiting stars other than the Sun: exoplanets. The easiest […]

Our planet is rare, precious, and fragile. It’s up to all of us to be its steward. With the advent of rocketry and spaceflight, our cosmic perspective changed forever. The very […]

If a star spins and then collapses, what happens to its angular momentum? The most common way to form a black hole in the Universe is to have a massive […]

There was a first molecule, and we found one just like it. But there’s a big difference. The Universe’s first molecule is found at last! That’s what the headlines have […]