Philip Plait's Blog, page 33

The best image ever taken of the cosmic web reveals the birthplace of galaxies

For the first time, astronomers have obtained large-scale images of the cosmic web — the incredibly ancient scaffolding of dark matter and hydrogen gas out of which galaxies in the Universe were formed.

This material is so far away and so incredibly faint that it took one of the largest telescopes in the world coupled with one of the most powerful cameras to see it at all. But what they found in their images was the very framework of the Universe.

The Universe formed about 13.8 billion years i...

Where did the waters of Mars go? Underground. Maybe Martian life did, too.

Mars today is pretty dry. The polar caps have water frozen in them, and there's some buried under the surface at mid-latitudes, but not a whole lot on a planetary scale; maybe enough to cover the entire surface of Mars to a depth of 20 to 40 meters.

Ancient Mars is another story. Billions of years ago there was a lot more. Estimates vary, but it may have been enough to cover the surface of the planet to a depth of 100 meters to as much as 1,500! Clearly, something dried Mars up.

Some of it eva...

Our first interstellar visitor 'Oumuamua may be an ice chunk blasted off an alien Pluto

In 2017, a mysterious interstellar visitor passed through our inner solar system.

Dubbed 1I/'Oumuamua, it defied explanation. Its orbit made it clear it came from interstellar space, but what was it? At first we thought it was an asteroid. When it passed the Sun and began moving back out into the depths of space, it was seen to be slowing, as you might expect as the Sun's gravity pulled it back… but it wasn't slowing enough. This made it seem more like a comet; if it were made of ice this would...

What tossed a supermassive black hole around in the center of a distant galaxy?

You'd think that tossing around a supermassive black hole equal to the mass of three million times that of the Sun's would be difficult. But for the galaxy J0437+2456 something did exactly that. The question is, what?

The answer, one way or another: Another supermassive black hole.

We think that every big galaxy has a supermassive black hole in its center, with millions or even billions of times the mass of the Sun. In general, we also expect this monster to sit in the exact center of the gala...

Zzzzzt! Mars might be sparky

Does lightning strike on Mars?

Given that the atmosphere there is pretty dry, it doesn't get thunderstorms. So, large-scale lightning bolts are probably nonexistent.

Still, what about smaller scale electrical discharges? There's reason to think those might exist on Mars. For example, on Earth, volcanic eruptions can create decent-sized bolts as ash particles rub against each other (and quite violently) inside the plume. This generates a charge via the triboelectric effect, when molecules in on...

A second wind – literally – for a scorching hot super-Earth

A nearby rocky planet orbiting very close to its host star may be sporting a second-generation atmosphere: It used to be more like Neptune, but the star blew the planet’s air away, and what we see now are noxious gases released by a magma ocean afterwards.

That’s pretty weird. But it’s also expected.

Planets form from a disk of material orbiting a young star. Farther out, where it’s cooler, are lighter atoms and molecules like hydrogen, helium, and ices; while closer in it’s too hot for those ...

Epic Martian cloud forms every summer day around an immense volcano

Every day in the late southern spring and summer, an astonishing elongated cloud forms around a gigantic volcano on Mars. This cloud appears every morning, grows to incredible length, and then dissipates before noon. This apparently happens every Martian year, but has been difficult to observe until recently by spacecraft orbiting the Red Planet.

And that in itself is amazing, because the cloud can get as long as 1,800 kilometers in just a few hours!

The cloud forms on the western flanks of th...

The Universe is acting funny. Or we’re looking at it wrong.

There’s a problem with the Universe.

Or, possibly, there’s a problem with how we’re observing it. Either way, something’s fishy.

In a nutshell, the Universe is expanding. There’s a whole bunch of different ways to measure that expansion. The good news is these methods all get roughly the same number for it. The bad news is they don’t get exactly the same number. One group of methods gets one number, and another group gets another number.

This discrepancy has been around awhile, and it’s not g...

A new nearby super-Earth’s atmospheric secrets may soon be revealed

Astronomers have found a super-Earth around a nearby star that will be perfect for future observations to determine what’s in its atmosphere. This is a very cool and important find.

The star is called Gliese 486, and it’s a red dwarf, a low-mass and dim one about 27 light years from Earth. That’s very close to us in galactic terms; only about 200 stars are within that distance. Gliese 486 is about a third the mass and diameter of the Sun, and shines with only about 1% of the Sun’s brightness. E...

A quasar at the edge of the observable Universe has its radio turned *way* up

Astronomers have discovered a powerful quasar very near the edge of the observable Universe, a staggering 13 billion light years from Earth. While many quasars at this distance are known, this one is special: It's "radio loud," meaning it's pouring out radio energy, making it part of a special class that can help us better understand conditions when the Universe was very young.

Quasars are themselves a special kind of galaxy. As far as we know, every big galaxy has a supermassive black hole in ...