The Astronomy Thread

[Krulle]

You mean the Krikkit?

[ShadowDragon8685]

Our current models of planet placement are pretty weak, and still can't really account for Hot Jupiters with much certainty. But really, it is more like the system of moons orbiting Jupiter than it is the planets orbiting the sun, in terms of distance vs relative size.

Yeah, the exciting thing is that we don't know how to explain half the stuff we're seeing in exoplanet arrangement. It's very unexpected.

The orbital distances of the TRAPPIST-1 planets are very much in line with a Jupiter-style moon system, but the masses are orders of magnitude larger. You've got cases of two Earth-mass planets passing within Earth-Moon distances of each other. That's kinda nuts.

I think the genuinely frustrating thing is that we can't hop some scientists on a ship and Warp 9 out there to see WTF is happening up-close and personal.

[Absalom]

You mean the Krikkit?

The sports reference was also intentional.

[icekatze]

hi hi

Since I know there are some other Planet Nine skeptics around here, I figured I would share this with ya.

Models of newly discovered body SY99 show that diffusion may be the cause of aligned orbits

While I try to remain unbiased, I really can't deny the fact that Michael Brown's smug attitude makes it easier for me to be on team skeptic.

[Arioch]

While I try to remain unbiased, I really can't deny the fact that Michael Brown's smug attitude makes it easier for me to be on team skeptic.

Heheh, I have to agree. Unfortunately, it's almost impossible to prove it's not there, so this issue may linger for a long time.

[Suederwind]

Earth's radio signals may be protecting it from space radiation: Link

Interessting, but short article about the Van Allen Belt and its (possible) interaction with radio signals from earth.

[Absalom]

Would have been nice if they had said whether they were just talking about loose electrons, or actual photons being pushed back.

[Arioch]

Wow.



I've watch a lot of animated cloud movement stuff for Jupiter, but never before noticed how fast the central band's movement is compared to the rest of the latitudes.

https://apod.nasa.gov/apod/astropix.html

[icekatze]

hi hi

Here's an interesting one: Smallest star identified by astronomers, only slightly larger in diameter than Saturn.

[GeoModder]

hi hi

Here's an interesting one: Smallest star identified by astronomers, only slightly larger in diameter than Saturn.

Wow. 300 g at its 'surface'? Why, the Sun barely pulls 28 times our body weight.

[Arioch]

That's what happens when objects get very dense; you can get very close to a large mass. The tides would probably be pretty hellacious, too.

Low-mass stars have a strange property where the puffy gas envelope of a huge gas giant crosses some tipping point and becomes compressed. Which is counter-intuitive, since you would think the new outward pressure from the fusion reactions would increase the diameter rather than shrinking it. Or maybe it's because the puffy outer layers get blown off as the process begins. But it's almost all hydrogen anyway, so I'm not sure that makes sense either.

[Razor One]

The universe isn't here to satisfy human sensibilities, so some counter-intuitiveness should be expected, and treated as suspect when it isn't found.

[boldilocks]

One day humans will sail among the stars and find it all terribly mundane and boring.
Until then, let's gape at these movies filmed by probes passing beyond where any of us can go, with a sense of childlike wonder.

[raistlin34]

One day humans will sail among the stars and find it all terribly mundane and boring.
Until then, let's gape at these movies filmed by probes passing beyond where any of us can go, with a sense of childlike wonder.

I´m not that confident. Between the insane amount of resources (specially fuel) it would require plus the extremely long distances...well, I don´t expect a real life Star Trek anytime soon.

[RedDwarfIV]

One day humans will sail among the stars and find it all terribly mundane and boring.
Until then, let's gape at these movies filmed by probes passing beyond where any of us can go, with a sense of childlike wonder.

I´m not that confident. Between the insane amount of resources (specially fuel) it would require plus the extremely long distances...well, I don´t expect a real life Star Trek anytime soon.

Perhaps not Star Trek.

I am reminded of Elon Musk's comments regarding the Falcon rocket landings, and how he hopes that they will become mundane rather than a huge event, because that'll mean they've become common enough not to care about.

The first sleeper/generation vessel sent to another star STL would certainly be a momentous event. If we started sending one every two years or so? People would accept it as a fact of life.

[icekatze]

hi hi

The two big things that determine the diameter of a gas giant is their mass and there temperature. Theoretical models suggest that Jupiter was twice as large early in its existence, and has been contracting as it cools. But thermal expansion and gravitational compression don't oppose each other in a linear manner. Jupiter would need somewhere between 50 and 75 times more mass to ignite fusion in its core.

EBLM J0555-57Ab is estimated to be cooler than some hot jupiters that have been discovered in close orbits around larger stars, suggesting that its internal fusion is so meager that it isn't doing much to counteract the much greater mass.

[GeoModder]

Imagine that, this borderline star would see the end of the universe if there was an end to it. Its fusion process is simply too 'slow' to convert enough hydrogen in time.

[Arioch]

Imagine that, this borderline star would see the end of the universe if there was an end to it. Its fusion process is simply too 'slow' to convert enough hydrogen in time.

Yeah, the smaller the star, the longer it will last.

[RedDwarfIV]

Imagine that, this borderline star would see the end of the universe if there was an end to it. Its fusion process is simply too 'slow' to convert enough hydrogen in time.

So... a nice place to ride out the heat death of the universe?

[GeoModder]

At the coldest star in the universe, yeah.