The Astronomy Thread

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icekatze
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Re: Alpha Centauri B b

Post by icekatze »

hi hi

I dunno, who can forget P3X-595? Its probably even more famous than P3W-451. :)

Alpha Centauri already has something of a legend surrounding it. Its present in science fiction literature and I think its mystique will carry on, at least until people start colonizing the place, at which point they'll probably pick something with fewer syllables.

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Re: Alpha Centauri B b

Post by saint of m »

Too bad we won't be alive when this happens, but it would be interesting to see what kind of life evolved on that planet. Do the two suns generate more radiation? Does this effect the the planet in some way if they do?

Is going to be a world like what was in Pitch Black, or Tatooine, or is it something else.


OOOh, the geek in me is coming out full blast with this.

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Re: Alpha Centauri B b

Post by fredgiblet »

Given how close it is to the star Mercury is more like it.

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Re: Alpha Centauri B b

Post by Arioch »

For a planet around either star, the secondary star would provide significant illumination, so there would be two "day" periods that would overlap to varying degrees during the year. "Night" would only occur during the parts of the year when the planet was on the opposite side of both stars. Then there's also the third star, Proxima Centauri, to consider, but I expect that wouldn't be any brighter than our moon.

But the biozone is going to be somewhat flexible for either star, because the secondary illumination is going to be very signficant, and the farther away from the primary you get, the closer you get to the secondary star (at least in certain parts of the year). Though the seasons may be widely variable because of this.

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Re: Alpha Centauri B b

Post by Absalom »

Well, I guess we now have a candidate for a light-sail probe. How many decades before we actually try :) ?

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Re: Alpha Centauri B b

Post by Count Casimir »

Arioch wrote:For a planet around either star, the secondary star would provide significant illumination, so there would be two "day" periods that would overlap to varying degrees during the year. "Night" would only occur during the parts of the year when the planet was on the opposite side of both stars. Then there's also the third star, Proxima Centauri, to consider, but I expect that wouldn't be any brighter than our moon.

But the biozone is going to be somewhat flexible for either star, because the secondary illumination is going to be very signficant, and the farther away from the primary you get, the closer you get to the secondary star (at least in certain parts of the year). Though the seasons may be widely variable because of this.
That's a really cool idea for a fantasy setting. Lots of fantasy settings with multiple moons, not enough with twin suns. Hmm....
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Re: Alpha Centauri B b

Post by discord »

asimov's nightfall.
nice little story.

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Re: Alpha Centauri B b

Post by Trantor »

Absalom wrote:Well, I guess we now have a candidate for a light-sail probe. How many decades before we actually try :) ?
Less than one, if ESPRESSO finds a second earth there.
sapere aude.

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Re: Alpha Centauri B b

Post by Mr Bojangles »

Count Casimir wrote:
Arioch wrote:For a planet around either star, the secondary star would provide significant illumination, so there would be two "day" periods that would overlap to varying degrees during the year. "Night" would only occur during the parts of the year when the planet was on the opposite side of both stars. Then there's also the third star, Proxima Centauri, to consider, but I expect that wouldn't be any brighter than our moon.

But the biozone is going to be somewhat flexible for either star, because the secondary illumination is going to be very signficant, and the farther away from the primary you get, the closer you get to the secondary star (at least in certain parts of the year). Though the seasons may be widely variable because of this.
That's a really cool idea for a fantasy setting. Lots of fantasy settings with multiple moons, not enough with twin suns. Hmm....
It's not really fantasy, but twin suns do form part of the backstory of Arthur C. Clarke's 2001 series of books. Unfortunately, he never goes into much detail, other than to mention the sheer confusion Earth's biosphere undergoes while adjusting to a near 24/7 daylight cycle that lasts for the better part of the year.

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Re: Alpha Centauri B b

Post by javcs »

Mr Bojangles wrote:
Count Casimir wrote:
Arioch wrote:For a planet around either star, the secondary star would provide significant illumination, so there would be two "day" periods that would overlap to varying degrees during the year. "Night" would only occur during the parts of the year when the planet was on the opposite side of both stars. Then there's also the third star, Proxima Centauri, to consider, but I expect that wouldn't be any brighter than our moon.

But the biozone is going to be somewhat flexible for either star, because the secondary illumination is going to be very signficant, and the farther away from the primary you get, the closer you get to the secondary star (at least in certain parts of the year). Though the seasons may be widely variable because of this.
That's a really cool idea for a fantasy setting. Lots of fantasy settings with multiple moons, not enough with twin suns. Hmm....
It's not really fantasy, but twin suns do form part of the backstory of Arthur C. Clarke's 2001 series of books. Unfortunately, he never goes into much detail, other than to mention the sheer confusion Earth's biosphere undergoes while adjusting to a near 24/7 daylight cycle that lasts for the better part of the year.
Part of the (relative) rarity of twin suns in comparison to multiple moons is probably because it's a lot easier to figure out or guesstimate (for the author) what multiple moons would do (funky tides, etc) than it is to figure out what multiple suns would do ... unless you're orbiting both stars, not passing between them (for whatever reason, probably some funky out-of-plane orbit), or the secondary component is far enough away that the light is sufficiently diffused to not be much brighter than bright moonlight.

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Re: Alpha Centauri B b

Post by Count Casimir »

You're probably right, javcs, but it'd still be a fun idea. The Times of Light and Darkness, underground cities, all that cheesy stuff. Mmm...
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Re: Alpha Centauri B b

Post by javcs »

Count Casimir wrote:You're probably right, javcs, but it'd still be a fun idea. The Times of Light and Darkness, underground cities, all that cheesy stuff. Mmm...
Oh, most definitely. It'd certainly be fun ... the problem would be making the indigenous life fit in with the multiple sun-aspect, and not doing something to mess things up for the audience.


As an aside, one other place where multiple suns were involved, and mattered, was in the movie Pitch Black.

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Re: Alpha Centauri B b

Post by Mr Bojangles »

javcs wrote:Part of the (relative) rarity of twin suns in comparison to multiple moons is probably because it's a lot easier to figure out or guesstimate (for the author) what multiple moons would do (funky tides, etc) than it is to figure out what multiple suns would do ... unless you're orbiting both stars, not passing between them (for whatever reason, probably some funky out-of-plane orbit), or the secondary component is far enough away that the light is sufficiently diffused to not be much brighter than bright moonlight.
There is definitely complexity there (3-body problem, anyone?) And that's likely why we never get the nitty-gritty details. But, such scenes do look pretty sweet as Casimir points out. In the case of the 2001 series, the second sun is actually what used to be Jupiter. Monoliths were used to collapse it until fusion started. So, no orbits were changed, everything is where is should be, and Clarke definitely made heavy use of his own saying "any sufficiently advanced technology is indistinguishable from magic."

Still, a very enjoyable series of novels. I'd recommend them.

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Re: Alpha Centauri B b

Post by javcs »

Mr Bojangles wrote:
javcs wrote:Part of the (relative) rarity of twin suns in comparison to multiple moons is probably because it's a lot easier to figure out or guesstimate (for the author) what multiple moons would do (funky tides, etc) than it is to figure out what multiple suns would do ... unless you're orbiting both stars, not passing between them (for whatever reason, probably some funky out-of-plane orbit), or the secondary component is far enough away that the light is sufficiently diffused to not be much brighter than bright moonlight.
There is definitely complexity there (3-body problem, anyone?) And that's likely why we never get the nitty-gritty details. But, such scenes do look pretty sweet as Casimir points out. In the case of the 2001 series, the second sun is actually what used to be Jupiter. Monoliths were used to collapse it until fusion started. So, no orbits were changed, everything is where is should be, and Clarke definitely made heavy use of his own saying "any sufficiently advanced technology is indistinguishable from magic."

Still, a very enjoyable series of novels. I'd recommend them.
Oh, it was definitely a good one. 2010, wasn't it?
Still, we never really got that much detail on the effects of Jupiter being ignited on Earth - we got details on the effects on Jupiter's moons, but on Earth, all we got (IIRC) was that there were 'changes' and 'upheaval' and nocturnal species got messed up (when Earth was in the part of its orbit where it was between Sol and Jupiter).
Even in 3001, there wasn't much detail ... and there'd been a lot longer to figure things like that out, but on the flip side, those details didn't matter for the story.

Yep, multiple moon/sun scenes generally look pretty cool - and details on what effects they have get left out because, really, most of the time, that's not going to be an issue in the story, and the vast majority of people won't even think about it, much less care - they're just going to care that it looks awesome and whatever plot/story-related points they get informed of.

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Re: Alpha Centauri B b

Post by Mr Bojangles »

javcs wrote:
Mr Bojangles wrote:Oh, it was definitely a good one. 2010, wasn't it?
Still, we never really got that much detail on the effects of Jupiter being ignited on Earth - we got details on the effects on Jupiter's moons, but on Earth, all we got (IIRC) was that there were 'changes' and 'upheaval' and nocturnal species got messed up (when Earth was in the part of its orbit where it was between Sol and Jupiter).
Even in 3001, there wasn't much detail ... and there'd been a lot longer to figure things like that out, but on the flip side, those details didn't matter for the story.

Yep, multiple moon/sun scenes generally look pretty cool - and details on what effects they have get left out because, really, most of the time, that's not going to be an issue in the story, and the vast majority of people won't even think about it, much less care - they're just going to care that it looks awesome and whatever plot/story-related points they get informed of.
It was indeed 2010 when Jupiter was lit off. And, those are pretty much the same details I remember regarding the second sun and how it affected Earth. It really just boils down to "hey, that makes for a pretty shot!" Personally, my favorite detail in 3001 was the ring around the world.

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Re: Alpha Centauri B b

Post by Arioch »

Day and night are pretty basic storytelling tools, so to have a system where both are variable really puts a lot of work on the author -- not just to work out the physics, but also a significant amount of expositional effort to explain what's going on to the reader. Until you've tried, you don't realize that you can no longer use basic concepts like "yesterday" and "tomorrow," etc.

However, the reality is that the majority of solar systems have more than one star.

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Re: Alpha Centauri B b

Post by Mr Bojangles »

Arioch wrote:Day and night are pretty basic storytelling tools, so to have a system where both are variable really puts a lot of work on the author -- not just to work out the physics, but also a significant amount of expositional effort to explain what's going on to the reader. Until you've tried, you don't realize that you can no longer use basic concepts like "yesterday" and "tomorrow," etc.

However, the reality is that the majority of solar systems have more than one star.
No doubt, Arioch. Trying to write about a multi-star system would be a very large effort. It's probably why we don't encounter it more in novels and such (physics aside). But, it's not too uncommon in sci-fi stories in a visual medium, because it's easier to show people two suns, rather than tell people about two suns. Like I said, it makes for a nice shot. :)

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Re: Alpha Centauri B b

Post by discord »

or one of my favorite lines,

Jack: Three suns?
Shazza: Bloody Hell.

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Re: The Astronomy Thread

Post by Trantor »

Milky Way in one pic. 9GP, zoomable:

https://www.eso.org/public/images/eso1242a/zoomable/
sapere aude.

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Kappa Andromedae b

Post by Arioch »

Japan's Subaru 8-meter telescope on Mauna Kea in Hawaii has directly imaged a large exoplanet around 168 LY-distant Kappa Andromedae.

Image

The planet (κAnd b) is 12.8 Jupiter masses, putting it right at the edge of being a brown dwarf, and orbits 55 AU from the primary (which is almost twice Neptune distance). The primary is a blue-white B9 subgiant of about 2.5 solar masses.

κAnd b is one of about a dozen exoplanets to be directly imaged, and is the most massive so far (that I'm aware of). In addition to the large size and scale of the system, it's notable that massive stars have very short lifespans, so κAnd is probably only about 30 million years old.

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