Philip Plait's Blog, page 25

When the Universe makes no sense, look at a pretty galaxy

What do you do when you find out there's something wrong with the Universe?

In the case of my old friend and colleague Adam Riess, you point Hubble Space Telescope at a gorgeous spiral galaxy.

There may be a wee bit more to say about that, but you know if I use the phrase "gorgeous spiral galaxy" then I'm going to show you, well, a gorgeous spiral galaxy.

The spiral galaxy NGC 3254, seen by Hubble in 2019. Credit: ESA/Hubble & NASA, A. Riess et al.; CC BY 4.0

Oof. Told ya.

That is NGC 3254,...

What caused an old, giant star to disappear for over half a year?

In the scheme of galactic magic tricks, one of the more difficult is making an entire star disappear. Especially with the added difficulty of making it reappear again a little over six months later.

Yet this is apparently what happened to a star halfway across the galaxy from us. In 2012, the star slowly faded over a few months, dropping in brightness by an astonishing 97% (that that, Betelgeuse!) before rising again at the same rate it faded. A drop like that is extremely weird, and very diffi...

This star cluster is slowly being taken over by black holes. In a billion years they’ll kill it.

A distant cluster of stars orbiting our galaxy has a dark fate awaiting it: It’s slowly being taken over by black holes, and in a billion years, just as it finally dissolves into space, it will be entirely made up of black holes.

This may sound weird, but in fact may happen fairly often to such clusters.

The object in question is called Palomar 5. It’s a globular cluster, which are usually tightly packed collections of hundreds of thousands if not millions of stars in a roughly ball-shaped col...

Drying up a claim — maybe — of liquid water under the south pole of Mars

In 2018, planetary scientists made a startling announcement: They had found evidence for a large lake of liquid water under the south pole of Mars.

This was surprising for many reasons. For one, while we know there's a lot of frozen water on Mars — the polar ice caps are mostly water ice, and it's been seen just under the surface down to mid-latitudes — evidence of liquid water was scarce. Also, the south polar cap of Mars is cold, so this water would have to be extremely salty to withstand the...

Hubble on the Bubble: Can NASA fix the world’s most famous telescope?

On June 13, 2021, Hubble Space Telescope detected a problem in one of its computers, and went into “safe mode.” It shut down all non-essential operations, closed its hatch, and awaited engineers back on Earth to figure out how to fix it.

But that’s turning out to be harder than expected.

The initial problem seemed to be in a memory module in its payload computer, which organizes and controls the science instruments onboard the observatory: its cameras, if you will. There are five scientific de...

A deep, deep photographic dive into the Cygnus the Swan

If you live in the northern hemisphere (or northern parts of the southern hemisphere) and go outside in late June or early July after the sky gets dark, you can see the Milky Way rising in the east. As it gets higher, you may notice a curious configuration of stars, like a huge cross-shape made of five stars.

This is nicknamed the Northern Cross, but officially it's Cygnus, the Swan. It's a decent-sized constellation, and because of its location along the Milky Way it boasts bright stars and a ...

The motions of 66 nearby galaxies have now been reliably measured. Not stars. *Galaxies*.

Everything in space moves.

Planets orbit stars, moons circle planets, stars orbit inside galaxies. Even galaxies themselves — those immense structures of billions of stars, gas clouds, dark matter, and dust — all move through space, their trajectories determined by the force of gravity of other galaxies around them.

Because these objects are all so terribly distant from us, they appear motionless in the sky, unchanging. But, over sufficient time, the stars can be seen to move. Astronomers call...

Tiny but mighty: Astronomers find the smallest but most massive white dwarf ever seen

Astronomers have found a tiny but mighty dead(ish)star, a white dwarf that is both the smallest and most massive ever seen. It also spins rapidly, packs a walloping magnetic field, and might eventually collapse into an even smaller and denser neutron star.

Seriously, this weird little thing has it all.

A white dwarf is what's left over after a star like the Sun dies. Right now the Sun is happily fusing hydrogen into helium in its core, providing it with the energy we receive as well as the pre...

Spacetime shakes: For the first time, astronomers see a black hole eating a neutron star

For the first time ever, astronomers have detected the scariest thing in the Universe eating the second scariest thing: A black hole devouring a neutron star.

This is simultaneously one of the coolest and most spine-chilling research results I've ever written about. A merger between these two densest types of objects in the Universe creates a colossal explosion, yet one that is utterly dark. The only way it was detected because it literally shook the fabric of spacetime.

Even better? Astronome...

Baby stars throw big tantrums. Very, very big tantrums. And they do it a lot.

Stars are fearsome things. Besides just emitting extraordinary amounts of energy all the time like it's a run-of-the-mill thing, they will sometimes also flare, blasting out tremendously huge bursts of matter and energy on a scale that only be described as "underwear-soiling."

Flares are magnetic events. As I've described them before:

[T]he Sun has a very complicated magnetic field. Inside the Sun there are enormous packets of hot plasma (gas with its electrons stripped off) that rise from dee...