What effects would you see on a terrestial planet in a binary system?

[jaws]

OK, I asked this in the Sci-Fi section to get an astronomical view of things, but this is actually for some fantasy world building. I am looking to compile the potential SFX that would be perceived by inhabitants of a planet that has 2 suns. Seasonal, day/night cycles, etc...

 

I am considering both options of an S-type orbit (around only one of the stars) and a P-type orbit (around both suns).

 

I am not really interested in making it real, just consistent enough for fantasy. Especially to consider all the cool effects that might derive from the situation.

 

Any help appreciated

 

Click here for the STAR HERO version of this thread

[Supreme Serpent]

Re: What effects would you see on a terrestial planet in a binary system?

 

At least for a fantasy world, you could probably keep the day/night and seasonal cycles pretty much the same if you wanted to.

 

First Dawn - first sunrise, early morning

Second Dawn - a bit later, second sunrise, leading to full daylight

etc.

 

Just a bit more gradation in the twilight type hours.

 

For a fantasy world, the obvious question would be about the Sun God(s). Parent and child? Rivals? Lovers destined to remain near each other but ever apart? Roughly equal in power or one clearly dominant? Worshipped together or individually?

 

Depending on how you work the rest of the world and how hot/bright things might be could determine how the Sun Gods are viewed. If summertime is especially hot and dangerous, they could be oppressive types. If the world is cold and the sun is more welcome could be seen as more nurturing.

[Jkeown]

Re: What effects would you see on a terrestial planet in a binary system?

 

There is a program I use called Celestia. I figured out how to write my own solar systems and then "stand" on one of the planets to watch the sky turn for a few virtual years to create a proper calendar for my main homebrew world.

 

After you get it working, you then alter the text files to move stars and planets around in infinite combinations until it looks and feels right. I even wrote a randomizer in TableMaster to output solar systems.

[jaws]

Re: What effects would you see on a terrestial planet in a binary system?

 

There is a program I use called Celestia. I figured out how to write my own solar systems and then "stand" on one of the planets to watch the sky turn for a few virtual years to create a proper calendar for my main homebrew world.

 

After you get it working, you then alter the text files to move stars and planets around in infinite combinations until it looks and feels right. I even wrote a randomizer in TableMaster to output solar systems.

 

 

Awesome!! that will save me a ton of work... I have been looking for various simulators but most are too scientific or just don't really do what I need but Celestia sounds perfect!! Great help!

 

BTW what is tablemaster?

[Korvar]

Re: What effects would you see on a terrestial planet in a binary system?

 

Tablemaster is a program for doing table lookups. Instead of hunting through a mountain of books for that one table to roll on, Tablemaster does it for you.

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

There is a program I use called Celestia. I figured out how to write my own solar systems and then "stand" on one of the planets to watch the sky turn for a few virtual years to create a proper calendar for my main homebrew world.

 

After you get it working, you then alter the text files to move stars and planets around in infinite combinations until it looks and feels right. I even wrote a randomizer in TableMaster to output solar systems.

 

This sounds terrific! How difficult is it to make your own solar system?

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

Oh, I almost forgot --- everything would have two shadows.

 

Unless one of the suns is very dim, but that's no fun.

[Drhoz]

Re: What effects would you see on a terrestial planet in a binary system?

 

Oh, I almost forgot --- everything would have two shadows.

 

Unless one of the suns is very dim, but that's no fun.

 

and the shadows would be different colours, if the suns were different spectral types. I believe it's called the Flammarion Effect

[jaws]

Re: What effects would you see on a terrestial planet in a binary system?

 

Tablemaster is a program for doing table lookups. Instead of hunting through a mountain of books for that one table to roll on' date=' Tablemaster does it for you.[/quote']

 

Cool will look for it. I love tables, they make life so much easier when properly used in my mainly ad libed campaigns.

 

Oh, I almost forgot --- everything would have two shadows.

 

Unless one of the suns is very dim, but that's no fun.

 

and the shadows would be different colours' date=' if the suns were different spectral types. I believe it's called the Flammarion Effect[/quote']

 

I had only considered this for the moon, but it is very true. I had considered my moon to go through some very interesting stages when both suns shine on it. Such as a yellow crescent with a red crescent on the other side with an orange center, making it look like some kind of reptiles eye.

 

Also the "red nights" when the yellow sun sets but the red sun makes nights "bloody eerie".

 

And other stuff like that.

 

For now I am considering the yellow sun the primary with the planet orbiting it elliptically to create the seasons. The sun is smaller than ours so the planet is closer giving it a period of 256 days (give or take a little, im not bothering with the fractions, makes my calendar easy) with 8 months 4 weeks a month 8 days a week. So I will name 8 seasons that mimic our 4.

 

The red sun orbits around the primary in an 80 year cycle also eliptical, the heat from the second sun affects the seasons with strong difrences notices about every 10 years, greating 8 Greater Seasons. Depending on the distance and position of the Red Sun. The sun is usually only visible for about half of every year. What season it is visible depends on the Greater Season (its orbit around the primary).

 

Of course this grafity stuff might get a little bit wild though but I am trying to get as realistic as possible with out geting WAY too complex.

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

and the shadows would be different colours' date=' if the suns were different spectral types. I believe it's called the Flammarion Effect[/quote']

 

I had only considered this for the moon, but it is very true. I had considered my moon to go through some very interesting stages when both suns shine on it. Such as a yellow crescent with a red crescent on the other side with an orange center, making it look like some kind of reptiles eye.

 

Also the "red nights" when the yellow sun sets but the red sun makes nights "bloody eerie".

 

And other stuff like that.

 

From what I've read, the difference in "color" isn't noticable until you get to M7 or so (or B2 the other way); it would all seem white to someone near the star.

 

Of course, if you want to go with the ol' cliche, go. Most people won't know it's not quite right.

 

 

For now I am considering the yellow sun the primary with the planet orbiting it elliptically to create the seasons.

Remember, incoming light changes as the square of the distance, so 10% closer in 21% more light; which ought to be enough for reasonable seasons.

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

Oh! Oh! Another thing I just remembered! Tides!

 

Tides will get stronger and weaker as the suns line up or get at right angle, just like on Earth with the Sun and Moon. It's called spring tides when their strong and neap tides when their weak.

 

And if you do eccentric orbits, it gets more complicated. I think tidal force depends on the cube of the distance. I could be remembering wrong though.

[jaws]

Re: What effects would you see on a terrestial planet in a binary system?

 

From what I've read' date=' the difference in "color" isn't noticeable until you get to M7 or so (or B2 the other way); it would all seem white to someone near the star.[/quote']

 

I may spread them out a little more then, but probably not enough.

 

Of course, if you want to go with the ol' cliche, go. Most people won't know it's not quite right.

 

Drat, didn't know it was a cliche already. Probably unread enough or just not the right books. I've really only seen a binary star in a noticible or important role in SW:A new hope. I have seen them mentioned in scifi series and it may have shown on an episode of some sci-fi show. But cliche? In fantasy? If it is, please point me to some books on the mater i would like to get some reading done on the mater. So I can do this justice.

 

Remember, incoming light changes as the square of the distance, so 10% closer in 21% more light; which ought to be enough for reasonable seasons.

 

Oh! Oh! Another thing I just remembered! Tides!

 

Tides will get stronger and weaker as the suns line up or get at right angle, just like on Earth with the Sun and Moon. It's called spring tides when their strong and neap tides when their weak.

 

And if you do eccentric orbits, it gets more complicated. I think tidal force depends on the cube of the distance. I could be remembering wrong though.

 

Really useful information! Thanks!

 

You must spread some rep blah blah blah!

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

I may spread them out a little more then' date=' but probably not enough.[/quote']

Oh, reddish vs. blueish is fine!

 

Really useful information! Thanks!

Glad to help!

 

You must spread some rep blah blah blah!

Hey, someone want to help this guy out? Rep the poor gal he couldn't, why don't you?

 

 

 

 

[Basil]

Re: What effects would you see on a terrestial planet in a binary system?

 

I just found this thread, after adding more to the thread on the Star Hero Board. It brings up something that would strongly affect people living on such a planet, so go read it.

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

Ms Superior follows the link, and returns.

 

:hail: That's a magnificent element for a setting! I'm surprised no-one ever used it before!

[PhilFleischmann]

Re: What effects would you see on a terrestial planet in a binary system?

 

With two suns there are more "periods" to measure time with.

 

A day is the rotation of the planet.

A year is the orbit of the planet around the sun(s).

But there's also the period of the suns' orbit around each other, which will be shorter than a year if the planet revolves around both of them, or longer than a year if the planet revolves around only one of the suns.

 

With a P-type orbit, the relative positions of the two suns in the sky will change over time, getting closer together and farther apart, and assuming they orbit in the same plane as the planet (which AFAIK is most likely) they will be in alignment when seen from the planet on occasion.

 

With an S-type orbit, the "greater year" or orbit of the farther sun might be a period of time used commonly by longer-lived races, such as elves.

 

And that doesn't even include the periods of the moon or moons.

[jaws]

Re: What effects would you see on a terrestial planet in a binary system?

 

Ms Superior follows the link, and returns.

 

That's a magnificent element for a setting! I'm surprised no-one ever used it before!

 

It's actually my heartfelt intention I am just trying to make it some what consistent so i don't have smoke coming out of my brain every time the seasons change, also preferably not to have smoke coming out of my wolds inhabitants brains either if it gets too hot .

 

But primarily to ensure I can maintain the suspension of disbelief. That is why i also went to the star hero board in search for some stronger facts from the hard sci-fi gang.

 

Ms Superior follows the link, and returns.

 

That's a magnificent element for a setting! I'm surprised no-one ever used it before!

 

With two suns there are more "periods" to measure time with.

 

A day is the rotation of the planet.

A year is the orbit of the planet around the sun(s).

But there's also the period of the suns' orbit around each other, which will be shorter than a year if the planet revolves around both of them, or longer than a year if the planet revolves around only one of the suns.

 

With a P-type orbit, the relative positions of the two suns in the sky will change over time, getting closer together and farther apart, and assuming they orbit in the same plane as the planet (which AFAIK is most likely) they will be in alignment when seen from the planet on occasion.

 

With an S-type orbit, the "greater year" or orbit of the farther sun might be a period of time used commonly by longer-lived races, such as elves.

 

And that doesn't even include the periods of the moon or moons.

 

I am going with S-type and my GRAND cycle is 80 local years (roughly 58 earth years)

[Ms Superior]

Re: What effects would you see on a terrestial planet in a binary system?

 

With two suns there are more "periods" to measure time with.

 

A day is the rotation of the planet.

A year is the orbit of the planet around the sun(s).

But there's also the period of the suns' orbit around each other, which will be shorter than a year if the planet revolves around both of them, or longer than a year if the planet revolves around only one of the suns.

 

With a P-type orbit, the relative positions of the two suns in the sky will change over time, getting closer together and farther apart, and assuming they orbit in the same plane as the planet (which AFAIK is most likely) they will be in alignment when seen from the planet on occasion.

 

With an S-type orbit, the "greater year" or orbit of the farther sun might be a period of time used commonly by longer-lived races, such as elves.

 

And that doesn't even include the periods of the moon or moons.

 

What are the meanings for "S-type" and "P-type" and what do the S and the P stand for?

 

Oh, and can you have moons? I thought the orbits wouldn't work.

[PhilFleischmann]

Re: What effects would you see on a terrestial planet in a binary system?

 

What are the meanings for "S-type" and "P-type" and what do the S and the P stand for?

No idea. I was just using the terms that jaws used.

 

Oh, and can you have moons? I thought the orbits wouldn't work.

I don't see why not, assuming the planet is far enough away from the sun and the moon is close enough to the planet that the sun doesn't bother the moon too much. And if it does, you can always say, "The moon is held in its orbit by magic."

[jaws]

Re: What effects would you see on a terrestial planet in a binary system?

 

What are the meanings for "S-type" and "P-type" and what do the S and the P stand for?

 

Oh, and can you have moons? I thought the orbits wouldn't work.

 

It is late so I cant remember which is which, but I think P type the planet orbits both suns while the other orbits one sun only.

 

Yes there is one moon. enough complications with 2 suns. Except for tonal variations and very different phases due to the reflection of light from 2 suns. It isn't much different than ours.

 

No idea. I was just using the terms that jaws used.

 

I don't see why not, assuming the planet is far enough away from the sun and the moon is close enough to the planet that the sun doesn't bother the moon too much. And if it does, you can always say, "The moon is held in its orbit by magic."

 

I can use magic as an excuse but I want to make astronomy/astrology affect magic not the other way around. The less handwaivium in the building blocks the stronger the foundations.

[Basil]

Re: What effects would you see on a terrestial planet in a binary system?

 

Oh' date=' and can you have moons? I thought the orbits wouldn't work.[/quote']

 

Interesting question. I don't know, but I think you'd have to have a fairly small moon fairly close in. Certainly, I'd expect something like Phobos or Deimos would be possible, while something like Luna would be "pulled loose" in very little time (astronomically speaking). Something in between might be stable over the long term, but I have no idea where "in between" is the largest-looking satellite you could get away with.

 

Since the OP wants multi-color effects, that requires a satellite that has a visible disk. This is going to be tricky to achieve(Deimos, for instance, is only 1.4 minutes of arc by 1 minute of arc when directly overhead at the equator; this is less than five percent by three percent the apparent size of Luna from Earth).

 

He may have to settle for something one half to one fourth the apparent size of Luna.

 

Hm..... I'll have to think about that some more.