Philip Plait's Blog, page 35

See the first *incredible* images from the NASA rover Perseverance on Mars!

On Feb. 18, 2021 at 20:55 UTC, the Perseverance rover touched down on the surface of Mars.

The flight down was successful and, by all accounts, picture-perfect. The rover landed in the 50-kilometer-wide Jezero crater, within about a kilometer of the “bull's-eye” targeted.

The first images are now being sent to Earth, and oh my, what images they are.

This one is just spectacular. A jaw-dropper.

This phenomenal shot looking down from the sky crane shows the rover hanging by cables under the cr...

Cygnus X-1, the first black hole ever detected, is more massive than we thought

Black holes are everywhere.

Luckily, space is big*, so even the closest ones we know of are pretty far away, thousands of light years distant. And we see them in every decently sized galaxy out here, too, from millions to billions of light years away.

But Cygnus X-1 is special. It was the first. The first ever detected, that is, and is still one of the closest we know. But new observations show that a few things we thought we knew about it weren't right, including its distance, mass, and even ...

Perseverance lands on Mars today! Here's what you need to know

Today, February 18, 2021 at 20:44 UTC (3:44 p.m. Eastern US time), if all goes well, another robotic rover will land on the planet Mars.

But we won't know if it worked until 20:55 UTC (3:55 p.m. Eastern), because it takes 11 minutes and 22 seconds for the radio signal to travel the 200+ million kilometers from Mars to Earth. Hopefully, at that time we will find out that the rover Perseverance has safely, if terrifyingly, set down on another world.

[UPDATE (February 18, 20101 at 21:15 UTC): PER...

Can a planet be bigger than its star?

I get questions.

After posting an article here on the blog about an extremely low-density "superpuff" planet, I got an interesting question on Twitter:

["Have we ever found an exoplanet that was larger than its host star? Is that possible?"]

My first reaction was, "Yes! Kinda." And then I thought about it a little more, and realized the answer is actually, "Yes! But if you mean a star like the Sun, it's unlikely."

Explaining it would be a bit much for Twitter, but as it happens I have a bl...

New analysis weakens — but doesn't kill — the case for Planet Nine (UPDATED)

A paper just published by a team of astronomers looks at the evidence for the idea that another major planet, nicknamed Planet Nine, orbits the Sun far beyond Neptune. What they found casts doubt on the case to suppose the planet is out there. At the same time, they cannot say the evidence points toward the planet not existing.

[UPDATE (Feb. 16, 2021 at 20:30 UTC): Mike Brown, one of the astronomers looking for Planet Nine, weighed in on this paper not long after I posted this article. He shows...

Incredible microscope images of molecules show what Titan's haze looks like up *very* close

Titan is the largest moon of Saturn, and the second largest moon in the solar system, about the same size as Mercury. Unique among moons, it has a thick atmosphere — despite the lower gravity, the surface pressure is 1.5 times Earth's at sea level.

Its atmosphere is 95% nitrogen (Earth's is 78%) and 5% methane. Normally that would be transparent, but Titan's air is loaded with haze — tiny particles about a micron across (one-millionth of a meter; a human hair is roughly 50–100 microns wide). Th...

Black holes swarm in the core of a globular cluster

Astronomers have looked at the nearby globular cluster NGC 6397 and found that, instead of a single massive black hole in its core, it's likely to have dozens or even hundreds of smaller black holes swarming around in its center.

Holy Kessel Run!

Black holes play an astrophysically important role in the birth and lives of galaxies, stars, and other objects. We know of two flavors of black holes: Stellar-mass ones, from a few up to a few dozen times the mass of a star that are created when mass...

Have astronomers finally found a planet around Alpha Centauri? Maaaaaaaaaybe.

A team of astronomers has found… well, something near one of the stars of Alpha Centauri that is consistent with it being a planet, possibly around the size of Neptune. However, to be very clear, it's not proven yet — it could be a dust cloud or it could even not be real at all.

Call me "cautiously interested." But if it is a planet, that would be very cool indeed.

Alpha Centauri is the closest star system to ours. It consists of three stars, a binary star consisting of Alpha Centauri A and B,...

Here are the best places to find ice on Mars

So you want to go live on Mars. It's smaller than Earth, but still has a lot of real estate. Where's the best place to call home?

NASA's mantra has been to follow the water — they're looking for evidence of past life, but for once and future humans, it's still a good idea. Water is heavy and nearly incompressible, so it's very difficult and expensive to take with you to Mars. That means finding it in situ, there on Mars, is critical for success. Also, water isn't just for drinking: It can be br...

Eclipsing binary white dwarfs, weird mergers, and peculiar supernovae

After so many years writing about astronomy, I am pleased to report that there are still things going on in the Universe that can make the hair on the back of my stand up.

Let me share a multi-part story with you about dancing dead stars, what strange beast remains after the music stops, and the sometimes explosive result. Very explosive.

White dwarfs are the leftovers of stars like the Sun after they die. When a star like that runs out of nuclear fuel it swells up into a red giant, blows off ...