Philip Plait's Blog, page 38

So how many supermassive black holes *are* there in Holmberg 15A anyway?

Around 760 million light years from Earth lies the galaxy cluster Abell 85, a mighty collection of about 500 galaxies all orbiting one another. At its center is the enormous elliptical galaxy Holmberg 15A… and I do mean enormous; some estimates put it at well over 50 trillion times the mass of the Sun, dozens of times more massive than the Milky Way.

All big galaxies have a supermassive black hole in their hearts, millions or billions of times the Sun's mass. In very rough terms the black hole ...

Mars. Is. WEIRD.

Mars is many things. It's cold. It's dry. It's spectacular.

It's also weird. Very, very weird.

At its south pole are a series of layered deposits, a huge region where nearly pure water ice mixed with dust and sand was laid down year after year eons ago. Wind erosion has carved this into beautiful terraces now. But when you zoom in, you see that there are regions where odd patterns dominate, an intricate and vast network of furrows, interwoven channels that stretch for many kilometers.

They're...

A baby star stabs through the heart of Orion

You might think of stars as pretty points of light in the night sky. You might even think of the Sun as a star, its presence stable and easy to take for granted.

But a star is a mighty beast; octillions of tons of seething gas, energy, magnetic fields, all powered by a nuclear furnace at its heart.

And when one is born it is not a calm and staid process. It is prone to vast outbursts, powerful enough to dwarf any concept we have of the scale, some blasting out without focus, and some laser-col...

In 774 AD, the Sun blasted Earth with the biggest storm in 10,000 years

In the year 774 AD, an enormously powerful blast of matter and energy from space slammed into Earth.

Nothing like it had been felt on this planet for 10,000 years. A mix of high-energy light and hugely accelerated subatomic particles, when this wave impacted Earth it changed our atmospheric chemistry enough to be measured centuries later.

Our pre-electronic societies went entirely unaffected by it. But were this sort of event to happen today, the results would be bad.

It was first discovered ...

The Universe is 13.77 billion years old. Probably. Maybe a little less. We're not sure.

A pair of papers recently published show that the Universe is 13.772 billion (plus or minus 39 million) years old.

That's cool! It also agrees with some earlier measurements of the Universe made in a similar way. Also cool.

What's not cool is that this doesn't seem to alleviate a growing discrepancy in measurements made in different ways, which get an age a few hundred million years less. While that may not seem like a big deal, it's actually a really big problem. Both groups of methods should...

Axions, dark matter, and neutron stars: How to find the Universe's most mysterious matter

One of the most outstanding puzzles in all of astrophysics right now is simply stated: What the frak is dark matter*?

We know it exists and we know it's pretty much everywhere in the Universe, we know the kinds of things it does and the kinds of things it doesn't do… but, embarrassingly, we don't know what it actually is.

We have some good ideas, so scientists have been looking to see if any of these ideas pan out. In a recent paper, astronomers report looking for one particular flavor of dark...

2020 didn't completely suck: Here are some cool radio astronomy highlights

The year 2020 may have been stinktacular terribleness in many ways, but it wasn't all stinktacular.

For radio astronomy, there were a lot of really important achievements scientifically. I am mindful this comes on the heels of the collapse of the Arecibo radio telescope, so 2020 managed to impinge even here. However, quite a lot of very cool science was achieved at observatories such as the Very Large Array (VLA), the Very Long Baseline Array (VLBA), and the Atacama Large Millimeter/submillimet...

Threading a cosmic needle: A fleeting glimpse of a dying star's final moments

As an astronomer, I'm used to events in deep space happening on time scales on millions if not billions of years.

But sometimes things happens much faster than that. Sometimes even on human timescales. That's the blink of an eye on a cosmic timescale, which makes the odds of catching an event like that really low. Unless, that is, there are lots of objects doing it, in which case you might, might have a shot.

There are a lot of stars.

When a star up to eight or nine times the Sun's mass dies,...

Is dark matter made of teeny tiny black holes from another universe? Welllll…

Yeah, you're gonna want to sit down for this one. It's a little a lot:

It's possible that dark matter is made of tiny black holes created at the very beginning of time by nucleation from bubbles of false vacuum that created baby universes containing sub-lunar masses of matter during an infinitesimally brief period of cosmic hyperinflation.

If so, a team of scientists think, this could solve several nagging puzzles about the Universe, including dark matter, gravitational wave sources, and an od...

Mars methane mysteriously missing

For many years, planetary scientists have been tracking a Martian ghost: methane gas.

It was first seen by ground-based observations of Mars back in the 2000s, then subsequently by spacecraft orbiting the Red Planet. But these observations barely detected it, and have been called into question time and again. There's been much debate, and some of the claims have been contradictory. No truly convincing observation of it has been made.

So the European Space Agency sent a probe to Mars called the...