A star orbiting past our galaxy’s supermassive black hole offered a chance to test relativity as never before. The supermassive black hole at the center of the Milky Way is the […]

Our Universe cannot be described by normal matter alone. Vera Rubin’s work led the way. Ask an astrophysicist what our Universe is made of, and you’ll likely receive a shocking surprise. […]

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 […]

Hunting for dark matter, neutrinos, and other elusive signals isn’t just a satisfying endeavor, it’s a way of life for Dr. Laura Manenti. We know that there’s more to the Universe […]

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 […]

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 […]

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 […]

Even the best science imaginable has its limits. In terms of ambition, it’s hard to ask for more than to know absolutely everything there is to know about the Universe. That’s […]

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. […]

Some claim that inflation isn’t science, but it sure has made some incredibly successful scientific predictions. So, you want to know how the Universe began? You’re not alone. Every other […]

Depending on how you measure it, there are two different answers that could be right. If you want to see what’s out there in the Universe, you first have to be […]

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 […]

How fast is the Universe expanding? The results might be pointing to something incredible. If you want to know how something in the Universe works, all you need to do […]

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 […]

Xenon-124 isn’t stable, and the direct detection of its decay could lead us to an even greater prize. Our Universe is old: 13.8 billion years old, to be precise. Many of […]

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 […]