Guild of Astronomers

Hobbes · **Joined:** Fri Nov 10, 2006 4:57 pm **Posts:** 8

The D'ni were writting books that link to other planets, in other times. They were living in a cave but on those worlds, one could see the sky, stars, and moons.

You can notice the sun (which is a star) of Teledhan, is "moving" so fast ! this is due to the rotation of the planet.

Minkata's got three suns... Eder Gira's got one moon.

It's possible with some information grabbed there and there to find out stuff about these systems, and where there are from D'ni (Earth).

Then, the Guild of Astronomers has been created, for this purpose and other geek or poetic or scientific stuff.

If you want to join, just go there and see if we're here (we're two members by now).

andylegate · **Posted:** Tue Feb 23, 2010 11:46 am

http://s11.invisionfree.com/Guild_of_Astronomy/

I started this up way back during MOUL. There have been people there, but I've not been very active at all in it over the years. If you have enough people interested, I could turn this over to you guys.

ThedStranger · **Posted:** Tue Feb 23, 2010 3:07 pm

Is it possible that the sun is rotating Teledahn? :shock:

Hobbes · **Joined:** Fri Nov 10, 2006 4:57 pm **Posts:** 8

No, it's not possible for a star to orbit a planet, for gravity and formation reasons.

MustardJeep · **Posted:** Tue Feb 23, 2010 4:49 pm

Eh, the d'ni invented the worlds first un-deflatable balloon. For safety reasons the first and last test of the balloon was done in teledahn since everyone had severe doubts as to if the knot holding it shut would stay tied or not.

andylegate · **Posted:** Tue Feb 23, 2010 5:11 pm

For Teledahn, from what I remember about our discussions, it works out like this:

The rotation cycle is something like 72 seconds (might be wrong, but it's SHORT considering the distance).

Several things have to be considered:

Teledahn (the entire planet) mass.
Teledahn size.

The star's mass and size.

Now, if we assume (yes, we have to assume) that Teledahn's mass and size are the same as Earth's (the mass is a good guess: our avies don't jump higher or shorter. Gravity appears to be working the same. There could be differences, but too small for us to see with our eyes, they'd have to be measured other ways. Ways that we can't do with the game, heh), then we have some solid numbers to work with as far as that goes.

Now you have to ask yourself: Teledahn's sun is moving in an apparent circular motion around the horizon. As we know here on Earth, the sun isn't moving around the Earth, but the Earth is rotating, giving our sun "apparent" motion.
For Teledahn's sun to move all the way around the horizon like that, Teledahn would have to be knocked over on it's side (like Uranus is) rotating that way, and where we link in is near the equator of the planet.
No problems there, as this is something that can happen to a planet.

But now let's talk about that 72 seconds. Due to how FAST we see the sun "move" around the horizon, we now have enough constants to do the simple math: R= D/T , with R being the Rate or Velocity of spin, T being the Time and D being the Distance.
The Earth is 24,000 miles around at the equator. It takes the sun 24 hours to go from where we see it in the morning, until we see it again in the same position the next day. R= D/T and we get our answer: Earth rotates at about 1,000 Mph or 0.27 miles per second.
If Teledahn is the same size as Earth, then we have to say: R= 24,000 / 72 seconds. That makes R= 333.33 miles per second, or about 120,000 Mph.
That's wild! And bad news. Earth's escape velocity is about 7 miles per second. Heh. That's how fast you need to go to escape the Earth's gravity.

So ask yourself: what would happen to a rocky planet, the size of Earth if it spins at 47.5 times the speed of it's escape velocity?

I had someone make a theory that the sun is actually a Fusion device of some sort that gives off heat and light, but is small enough to orbit Teledahn.
Nice theory, except for that speed.It's just going too darn fast. If it's in orbit, that means the distance it is covering is even more in the same time, which means it's speed is even greater......which means it won't stay in orbit.

My theory is that of the first one: Teledahn rotating on it's size. But it's not the same size as Earth. It's a LOT smaller, but is mostly made up of very dense materials, so it's mass is increased. Due to it's smaller size, that mass would still work out to be the same as Earths, but the distance of rotation would be a LOT smaller, there for the velocity of rotation is a lot less.

But then again, who knows? :lol:

Hobbes · **Joined:** Fri Nov 10, 2006 4:57 pm **Posts:** 8

Hum interesting reasonning. Teledahn may be one of those unstable worlds we heard of in the books.
A collision can have made it spin very fast, and.. who know's what's going to happen?

Hobbes · **Joined:** Fri Nov 10, 2006 4:57 pm **Posts:** 8

Here's my KI if you want to join the Guild of Astronomers ! 00906268

Marein · **Posted:** Tue Feb 23, 2010 7:26 pm

andylegate wrote:

http://s11.invisionfree.com/Guild_of_Astronomy/

I discovered this forum not long ago and was saddened that you have to be registered in order to view the posts, and moreover that new registrants have to manually approved (which hasn't happened so far

). I'd love to see what kind of discussions have been had!

andylegate · **Posted:** Tue Feb 23, 2010 8:28 pm

It's because once MOUL shut down 2 years ago, a lot of interest left with it in this kind of Guild. I also put it together prior to Cyan anouncing the 5 major guilds and releasing the Guild Pubs.

At that point, I became heavily involved in helping build the current GoMa. I was also spending a LOT of time learning how to use Blender and create Ages.

Due to the lack of interest, I locked it down (was getting spam bots left and right).

I'm still very busy with the GoMa and I'm in the middle of 3 Age Creation projects, so I'm afraid my time is very limited.

As I said, if any of you would like to take over this forum, simply PM me and I will send you the system admin username and password, and you can take over. It's on a free server and the software was free, so it won't cost anybody anything, and you'll have the freedom to do what you want with it.

If you instead will be starting up you're own forum and online area, please let me know, and what I will do is take this one completely down. I'll also need to PM the Mods here, as the forum I started up is actually listed on one of the outside resource links listed by Cyan.

Marein · **Posted:** Tue Feb 23, 2010 10:24 pm

To be honest I don't necessarily want to take over the forum and start it up again as much as I'd like to preserve the valuable discussions, discoveries, information etc that it already contains. Preferably I'd like to just have some login info with which to access the topics, but if I need to take over the whole forum to get to them, so be it

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

i like your thinking regarding tehedahn, andylegate. and i have done a bit more work off of what you have there. i am not going to post all of the calculation here, but it seems as though the target size of our planet to make the rotation speed equal to that of earths, would be a planet with a radius of 5,122 meters (terribly small) and a mass of 3.854 E18 kg. this planet would have a surface gravity equal to earths, but there is a problem. the gravitational equation is F = GMm/R x R

where F is the force of gravity, G is the gravitational constant, M is the mass of the first body, m is the mass of the second, and the R's are the radius.

since force equals mass times acceleration we can work out a new equation for the acceleration of a body due to gravity.

a = GM/R x R

and as we can see from this it will not take a very large change in R for the acceleration on a body to change. that is to say that the force pulling a body would likely be noticeably different at different elevations. the full range of implications form that i can not begin to imagine.

of course, more than that, the size of the planet would likely be.....noticeable.

Edit: i think if we assume that all observations regarding teledahn are correct, then the planet must be near earth size, the the 'star' must be some kind of small, fairly close, and most importantly self guided (that is that it would likely have to correct its course to stay in its orbit) fusion device. i see no reason why the device could not do that however.

andylegate · **Posted:** Mon Mar 01, 2010 10:50 pm

1helios1 wrote:

where F is the force of gravity, G is the gravitational constant, M is the mass of the first body, m is the mass of the second, and the R's are the radius.

since force equals mass times acceleration we can work out a new equation for the acceleration of a body due to gravity.

a = GM/R x R

and as we can see from this it will not take a very large change in R for the acceleration on a body to change. that is to say that the force pulling a body would likely be noticeably different at different elevations. the full range of implications form that i can not begin to imagine.

of course, more than that, the size of the planet would likely be.....noticeable.

Yah, I saw the problemt that the effect of gravity would change drastically by very shot elevations. I haven't sat down to work out the math, but in simple terms, when you first link in would be earth norm (1 gravity), but then when you get up to Sharper's Office with the fish tank, you might be bouncing around like you're on the moon, heh.
With such a short radius (just over 5 km), you may, or may not see that. It depends on a few things:
Here on Earth, you can see out to approx 20 miles (uhg, wait, metrics, sorry, I'm used to using miles vs Km's, heh) we'll say almost 40 km before the curve of the earth. A ship sailing away would get smaller of course, but once it got to about 40 km, it would appear to sink in the ocean, when all that is happening is that it is sinking below the curve of the earth.
Height changes that of course. Ships steaming to New York city see the tops of the sky scrapers there well before they get within 40 km of port.

5.1 km for a radius is like OMG!!! As far as a planet goes (uuuuuuhhhhhhmmmm, er, "Planet" okay, they redefined that term.....I'd have to say that if Teledahn was indeed that small, it's not even a Kuiper object! It's an astroid), the moon is around 6,000 km in diameter, the curve would be seen from about 6 km away I believe, so you would see that......

....or would you?

Keep in mind the illusional effect that can play on our eyes. Surrounded by water that's flat and calm, with nothing on or near the horizon, it would make it almost impossible to tell how far or close the horizon was.....until something got near it that we could reference with size (a ship, cloud,.......Shroomie!). Ahnonay Spheres are a very good example of creating that illusion.

For those of you that have a hard time grasping that, try this as an experiment....
Watch the calender for the next full moon, the 15th of March I believe. If you watch as the moon rise, as it's close to the horizon, it will look very large to you. Wait a few hours or 4. Then go back and look again, as it's much higher in the sky, it will look smaller. Now, while you were doing this, have a large,round asprin pill in your hand. Hold it at arms length when the moon rises and compare the size. Do this again when you've waited those few hours and the moon is higher in the sky.
The answer will be: the size comparison will be the same.

Most scientist agree that the reason the moon looks so much bigger at the horizon than high in the sky, is that close to the horizon, you have objects in the foreground to compare it to, and introduces an optical illusion.

How does that saying go? "Things are not always as they appear." ?? heheheheh.

1helios1 · **Joined:** Fri Oct 02, 2009 11:44 pm **Posts:** 44

i am little confused, perhaps i am misunderstanding you. the horizon distance is subject to height of the viewing perspective, and assuming a 6 foot tall person, at sea level, the horizon should only be about 3 miles away. i did the calculation myself so i might be in error. now, i make the horizon at sea level of teledahn, and viewed by a person six feet tall, to be 135 meters away. you will have to forgive me for using metric and us customary units, i use metric for calculations, but i dont really think in it.

anyway, i do some work with simple perspective tricks, and i think the illusion would likely hold, except for when you change elevation. if one were to watch the horizon as one travels up to sharpers office i think that would give it away, but i cant say for sure, my thinking is that the higher the viewing point in relation to the radius of the planet, the lower the horizon would be in the sky, that is to say the lower the viewing angle. we could calculate that easily and see how much of a difference it would make.

more than that though, i would think that the rather than a straight horizon line, it would be noticeably curved.

perhaps teledahn is flat!

andylegate · **Posted:** Tue Mar 02, 2010 11:32 am

Quote:

perhaps teledahn is flat!

Waaaaaaait a sec!

Heheheheheheheheh. We've (the fans) have been spending YEARS trying to figure out the mechanics of Teledahn so the don't violate the normal laws of physics that we know of.

Heh, what if you're right?

What if Teledahn is a "Sphere" like one of the Ahnonay spheres? Only larger, and it's sphere rotates on it's vertical access with a large man made (D'ni made) light source?

heheheheheh. It worked for Kadish in fooling people.

Love the speculation and theories btw! :lol:

Guild of Astronomers

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