The dream of multi-messenger astronomy is to seen an event with gravitational waves, neutrinos, and light all together. The newest candidate just might get us there. When it comes to cataclysmic […]

And it’s not because of leap seconds; it’s a fundamental property of most days. Human beings, in marking the passage of time, account for each day equally: with 24 hours. One […]

A case for looking beyond the planetary scientist’s (or even the astronomer’s) definition. Ever since 2006, when the International Astronomical Union (IAU) officially defined the term planet — introducing the term ‘dwarf […]

You get out what you put in, and we haven’t truly invested in space since Apollo ended. Humanity should be an interplanetary civilization by now. There is no scientific reason that […]

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 […]

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 […]

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 […]

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 […]

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 […]

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 […]

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 […]

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 […]

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 […]

Well-lit cities and towns are essential to public safety. That doesn’t have to ruin the night sky. For most of us here on planet Earth, navigating the world at night is […]

Now that we’ve seen our first one, we want more, and we want them better. Here’s how to get there. To resolve any astronomical object, you must achieve resolutions superior to […]

It’s the technique, from the Event Horizon Telescope, that brought us a black hole’s image. Here’s how it works. The Event Horizon Telescope has accomplished what no other telescope or telescope […]

And what do we still have left to learn? The original idea of a black hole goes all the way back to 1783, when Cambridge scientist John Michell recognized that a […]

When the Universe gives us clues, we ignore them at our own peril. When you approach the world scientifically, you seek to gain knowledge about how it works by asking it […]

We assume that life is ubiquitous in the Universe. But what if it’s just us? When it comes to the question of extraterrestrial life, humans optimistically assume the Universe is prolific. […]

What should a black hole look like? Our theoretical predictions are about to meet our first observations. In science, there’s no moment more exciting than when you get to confront […]