h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Our Sun gets brighter as it ages. In 1.1 billion years it will be 10% brighter. Adjust your camera exposure settings accordingly.

Unfortunately, that characteristic has not been passed down to me.

Here's a question: Will the sun ever get bright enough and hot enough that it could hypothetically support life (as we know it) on one of Jupiter's moons?

Multi-cellular, complex, terrestrial life. To be specific.

That would be . We could all move there.

But wouldn't that cause Jupiter's gasses to evaporate?
The moons would be enveloped in a huge 'nebulous' cloud.
Unable to see where they were going they'd likely collide.


~jwf~

I'm intrigued by the idea the Saturn's moon Enceladus is likely hospitable to aquatic life as it almost certainly has large liquid water oceans beneath its icy surface. Now whether any such life exists there or not is yet to be determined.

Yes, I know. BUT, millions or billions of years down the line, could the sun theoretically get hot enough to support terrestrial life on one of Saturn's or Jupiter's moons?

Can't tell you. That wouldn't be a useless fact.

Phil Plait's book, Death From The Skies, goes into good detail about the phases the Sun will go through in the future. It does indeed expand outward to envelope the nearer planets. But off hand I can't remember all the details such as how far out it might go, or what might happen to the gas giants along the way.

Modeling of the dynamical system The Solar System from recent years indicates that the orbits are not likely to be stable enough for changes in the Sun to be the bigger concern than the possibility of spiraling toward or away from it, contrary to prior assumption.

Plus our galaxy collides with Andromeda in just 2 billion years, so all bets are off.

That's gonna be a big one. I hope the Illuminati have the insurance premiums fully paid up and the policy covers more than third party, fire and theft. They'll need some independent witnesses too.

In the U.S. there are two types of wrestling: Fake and real. The fake kind is called "Professional wrestling" and the real type is called "Amateur wrestling".

That is so true. And so beautifully expressed.

...even including Neptune's trojans? (Yes, as a matter of fact.) and the TNOs? (Trans-Neptunian objects) ...probably not, but there is a saving verbalism, only objects inside the orbit of Neptune can be considered asteroids, while bodies of like size farther out are called 'comets'.

http://www.greywyvern.com/widgets/planetwerks

Post 9056 in response to post 9020.

Here's more from my source, Phil Plait, on the subject of the combined mass of asteroids.

~~~~~~~
You might think of the asteroid belt as loaded with rocks, billions of them of all sizes. In a sense that's true - there are billions of them! - but most are pretty small. We humans have a terrible sense of scale. If you take a billion rocks 10 meters across and smash them together into a ball, how big do you think it would be? I bet you guessed way too small: they'd form a sphere only 10 kilometers in diameter - about the height of Mt. Everest!

The asteroid belt has lots of rocks, but they're dominated in size by just a few big ones, and the biggest is Ceres, 900 km across. Even being generous, if you added all the other asteroids together, you'd get a ball maybe a little over 1000 km in size. The Moon is roughly 3500 km across, so there you go.
~~~~~~~

So, he's talking about just the ones in the asteroid belt. Comets typically are icy and not as rocky as asteroids.

I was going to post the factoid* that the Sesame Street characters, Bert & Ernie, were named after the cop and cab driver in It's A Wonderful Life, but didn't since it's a factoid and not, in fact, true.

Instead here's another astronomical one: Galileo observed Neptune in 1612-13, 234 years before it was discovered.

http://www.nature.com/nature/journal/v287/n5780/abs/287311a0.html

*the term "factoid" was originally coined to mean something that seems like a fact, but isn't. Because of modern (mis)usage, it can mean either a fact or not a fact. This was discussed way back in this backlog somewhere. I stick with the original definition as it makes more sense, as in a humanoid is not actually a human.