Virtual Astronomy

I've been building a smallish stone circle (think stonehenge, minus the major highway and the anti-tourist barriers) on a bluff in Immaculate (170,99). Naturally I wanted to set things up so that the megaliths aligned with astronomical events--sunrise and moonrise, basically.

My initial hypothesis was that the sun and moon rose and set in the same places every day, but this is not the case. Which is kind of cool. I've been making frequent observations, hoping to discern a pattern, and whether there are analogs to the solstices that my stonehenge can align with. Which sounds geeky, but, hey, if you're going to enact bloody and terrible virtual rites of sacrifice in a stone circle, you have to time them correctly, or else what's the point?

This has led me to do some serious pondering of things celestial in Second Life. Here are some initial observations:

Day and night: The day (sunrise to sunrise) is pretty much exactly four hours long. Daytime is 3 hours, night is 1 hour. By my reckoning, sunrises are at about 10:25, 2:25, and 6:25, Pacific, AM and PM.

The stars are mysterious. They appear to be fixed in the sky (they don't rise and set like the sun and moon), but the constellations change from one night to the next. So it seems there are multiple night skies, or the stars array themselves randomly every night, or the stars move only during the daytime.

The moon is 2-dimensional, and semi-transparent (you can see brighter stars through the darker parts of the moon when it passes in front of them). The moon tracks a far more southerly path against the sky than the sun does, making a smaller arc (it has to, given how much shorter nights are than days). The next solar eclipse will be exactly NEVER.

Unanswered questions (things I'm still working on): (1) are there other planets? I haven't noticed any moving against the stars, but I have not been observing long enough to say. (2) is there a regular cycle to the way the sun and moon shift their locations, or is it random? It appears that there is a pattern to it, but I haven't seen the extremes yet, and haven't followed it through a complete cycle. For the sake of my project, I certainly hope so. (3) How many stars are there, anyway? Actually I DO know the answer to this one, but you'll get SO MUCH MORE out of counting them yourself <g> (4) If we asked them nicely, would the Lindens give us a comet or a meteor shower?

In any case, I'm starting to compile a Second Life Astronomy FAQ, which will be available via notecard from my property probably by the end of this week. Contributions, questions, & corrections will definitely be welcome.

Follow-up here or message me if you're interested in either space-type stuff OR bloody and terrible virtual rites of sacrifice...

Jay ["Starseeker" Might be More Appropriate] Powers

Great idea Jay!

Well first of all, I think all the bright objects in the sky are stars (the all twinkle) and I think there is a set pattern to the way the sun rises and sets, but I don't know it. The system is, as of now, some degree local. I heard that there would be global weather and skys in 1.1 (Lindens, may you verify this please?) And I don't think meteor showers are integrated in SL, but it would be uber cool if there were.

Ah the celestial mysteries of SL. We'll never tell. Well maybe a little.

All good and correct assertions thusfar. With a bunch of real-world physics folks on staff, we've given lots of though to how things like the weather and celestial bodies work. The sun rising in different places is a good example of that (great observation!) - there is indeed a concept of 'season' in SL.

Neat, Jay! My current project is a solarpowered timepiece (iow, sundial) that chokes at night, so the SL day/night is important to me. Thanks for working this out.

I'll definitely have to come and check it out (I meant to tonight, really I did) when I'm not about to fall face first onto the kbd.

And the observations are really cool. I look forward to seeing the SL Astronomy FAQ inworld!

Jay, I'm amazed at the amount of thought and planning you put into this. Is there any chance I could get you to write up an article (about 4-5 paragraphs) on what you've been doing and what your future plans are? I'm pretty sure that this could lead to a lot of different products being made (such as star charts, telescopes...etc) in SL. A great deal of people don't read the forums, but I think that they should know about this. Could I set up a time to meet with you and discuss what you've done?

This is totally awesome. I looked up at the sky while I was builiding and just figured it was just a random starmap... but to think that the programmers put in Constellations and seasons into the sky, and just didn't tell anyone... well

I'm thoroughly fascinated, and I want to hear as much as possible about this subject Maybe you could also write a few articles for the Gazette once it gets up and running too?

Keep working on it, Jay. You have at least one riveted listener for your discoveries

Lordfly

I've stopped by Jay's observatory a number of times, talking to him about both of our projects. It does seem as though the sun and moon move in different rotations, almost in an eliptical pattern and shifts some each rotation. Which would make sense if they wanted them to look like real life. But you should defiantly check out his observatory if your interested in this stuff. Maybe even stand there and check out how close he is to getting it set up. It's quite amazing to see how he set it up, and how close he was to finishing it, then realizing the sun and moon shift.

hey jay, damn fine work! now there is at least one lsl command that could help you in your quest for celestial knowledge. llGetSunDirection. this maps the angle at which the sun is relative to the sim, which means we could set up a nice little track the sun through its path. then given these points, it is possible that we could derive their equation. heh i contemplated this a couple times, but never got further than making a sundial.

so i have a semi-puzzling question, do the sims revolve around the sun, or does the sun revolve around the sims?

Jay,

This is great work. Keep us posted on whether you identify any repeating star patterns - we could make up constellations and try to spot them at night, like the Hippo, or the Big Red Dragon. I have a planetarium ceiling planned for the Starlight Lounge out at Kazenojin - a classic constellation map would be a great asset! Even if you don't spot any repeating pattern, such a map would be a great tourist item.

Nada: I think the sun revolves around the sims, because my observation says that the whole sky is a bunch of spheres with alpha channels and diffrent overlapping textures.

Is the planet round, and if so, could the sun be up in one sim but down in another if the world were expanded out far enough?

The world is flat. This is proved by the inability of people to fly from Slate to Darkwood without flying over other sims. Moreover, the sun revolves around the sims.

Any differing opinions will be met by the Spanish Inquisition. So there. Neener.


This post brought to you by the SL Flat Earthers and the number 57.

Thanks to everyone for the hugely positive feedback. It's been fun watching the sky, playing at being a scientist...or a mad druid priest. Whatever.

I tend to agree with Darwin and Nergal that the world is undeniably flat. Sun, moon, stars embedded in rotating crystal spheres, etc. Further, my observations suggest that the sims collectively rest on the back of a giant tortoise named Mike, who is fond of veggie burgers and reruns of Melrose Place. The wonders of Science!

Now that Nergal's planted the ideas, I'm very tempted to start a Second Life Flat Earth Society. Or a Spanish Inquisition...

Nada: Thanks greatly for the scripting tip. I imagine it was intended for things like sunflowers and such. I will play around with it and see what kind of data it generates. I may bug you for help about that.

Ananda: YES! I'm very hopeful there's some regularity to the stars. Think a name the constellations contest would be a lot of fun...and a planetarium at kazenojin is yet another great idea for the redesign. I'll keep you posted if/when I figure anything out.

Thanks again, all.

Jay Powers

NO ONE INSPECTS THE SPANISH INQUISITION!

Except maybe the knights who say "Ni!"

Hehehe. Yeah, we should start the Second Life Flat Earth Society, and protest any hypotheses that the world is round!

Anyone else?

In May I determined that SL exists in the southern hemisphere of whatever planet it's on. Pretty far below the equator, too.

Matter of fact... today I watched the sunset and sunrise... the night seemed VERY short and the sun disappeared and reappeared far to the north... kinda confirms my earlier observation, which would place us well south of the 40th parallell. Maybe in the sub(ant)arctic zone. Shouldn't it be snowing or something? Sleet? Help me out here.

We may be lucky to be in the south polar region ... perhaps the "equatorial" zones are blazing hot! I suppose a flat "planet" can have "parallels"; hmm, in fact they might be actually parallel, depending on *how* flat the world is.

Some budding cartographer needs to devise a system for numbering the parallels and, uh, the-other-lines-at-right-angles-to-the-parallels-along-the-north-south-axis.

Also some budding astronomers should determine whether solar and lunar behaviour are synchronous at far limits of the world. This would be useful to determine the amount of flatness in the world, for example.

-- Athos Murphy
GSLR proprietor

As much as I believe that this stuff was all just thrown into the game without any thought just to get a seemingly realistic system (ahem, to non-scientists anyway), I find this strangely fascinating. Astronomy is a 1st life interest of mine, perhaps I will look into making it a 2nd life one as well. Hehe..

Oh...and don't you guys think maybe the world -might- be round? Oh and my best friend Galileo said... *notices crowd*

*runs away and hides*

(ps I'd be interested in joining an astronomy/science group)

Huns: curious what makes you think we're "south of the equator"; I was just about to conclude that the sun behaves as though we're in the northern hemisphere (or we would be if the world were round). 3 RL days of data indicate that as SL days get longer, the sun rises and sets further to the north.

Your observation that something strange happened today is correct, though. There was a glitch in the day/night cycle this morning. The SL day that began at 8:09 Eastern RL time didn't end until about 11:19 Eastern RL, lasting a good 15 minutes longer than "normal." Still trying to come up with a pseudoscientific explanation for that. Nowhere near enough data yet to determine if it happens regularly.

The chart I'm building of the solar cycle is actually kind of pretty (as Excel goes). See the attached image file. This morning's day length anomaly sticks out. (BTW, for my purposes, a day starts when the sun is completely above the horizon, and ends when the sun first touches the horizon while it's setting. Just so you know.)

Athos: seems a little early to be thinking about a lat/long system for SL when the sim-by-sim grid works okay for designating position. However, if we decide at some point that parallels and meridians are needed, I get to call Greenwich!

Garoad: NO! the world is FLAT! No one will ever convince me otherwise. But YES to the SL Astronomy Society. Will start a group; anyone interested, please IM me or post here and we can scope out what the interest level is like.

Thanks.

-Jay

Oops, here's said Excel chart...

-Jay

"the night seemed VERY short and the sun disappeared and reappeared far to the north... "

I think that's what leads him to believe that. Makes sense... closer to the poles night is shorter (edit: ok it's late at night and I may be totally confused right now. probably in fact) and if you're south of the equator the sun should "seem" like it's towards the north in the sky.

But that chart is cool--wonder what caused that weird blip in the data? Maybe the lindens changed the time on their servers, hehe.

I'll IM you.

I guess you don't want to hear about my friend Columbus, then huh?
You sure you're not religious?

Many ideas, there, Garoad.

First off, are you talking about Columbus Appleby? He's a shiftless, no-good sort. Just trying to trade on Darwin's good name.

Seriously, though, CHRISTOPHER Columbus BELIEVED he'd proved the world was a sphere, but he didn't really. He didn't make it all the way around (but he thought he had). All he really proved was that the world was much bigger than Columbus himself had assumed. It wasn't til the Magellan expedition made it to Asia, and from there back to Europe (without, of course, Magellan) that the "sail west to go east" proof was successfully completed.

There are 5 ways I can think of to scientifically determine whether a world is mapped onto a sphere or not.

(1) Phases of the Moon. The ancients knew the world was round because the shadow the Earth casts on the moon is always round. In SL, there are no phases of the moon at all, so this method won't work.

(2) The Magellan Proof. Show that people can repeatably go west from Gibson and get to Federal, without teleporting and without it being a bug. Right now, people can't, so this is also not a good method in SL.

(3) The Sun Proof. Eratosthenes took careful measures of the sun's angle at specific times, from widely dispersed places, and used differences in the angle to compute an accurate circumference of the world (circumference implying, of course, sphere). See this link for discussion. I will undertake this tonight, and see what I find.

Actually, there's a simpler method using the sun if all we care about is round or not. If the world's round, there have to be time zones; the sun has to rise later in Bonifacio than it does in Shipley. Will look into that.

(4) Center of Gravity. If the world is round, all objects that fall under gravity should fall toward its center of mass. The vectors of falling objects in two or more distant locales should converge if the world is spherical. If the vectors are parallel, the world if flat. Anyone feel like checking into that?

(5) Duel it out. We will fight on the field of honor, and whoever kills the other is correct. Okay, this one isn't scientific. But it might be fun.

There's a problem with both (3) and (4), in that it's hard to tell if the world is FLAT or if it's just a really, really, really big sphere. But given that we can measure vectors to a high degree of accuracy, the two are for practical purposes interchangable.

As for the religious or not question, for most of the history of science, scientists viewed their work as inherently religious. It's only the radical fundamentalists (and the extreme atheists) who invented the notion that science and religion are incompatible. Even Einstein said "God does not play dice with the universe," though whether he meant it literally or not, I admit I don't know.

At the end of the day, all this astronomy stuff is just reverse engineering the mathematics that underpin SL as Linden Labs designed it. Because it's neat, and it makes me appreciate all the thought that went into the place all the more. Of course, now that I've expressed it that way, I wonder if it's legal to reverse engineer virtual world intellectual property under the DMCA. I'll have to hope the Lindens find it amusing. Business model for God: sue scientists for violating copyrights/patents on entire universe.

-Jay
Astrono-Wanna-Be

A couple of corrections:

-- Christopher Columbus didn't set out to prove the world was round. At the time, it was already agreed by educated people that the world was round; they even had a good idea of its size. Columbus disagreed about its size; he thought it was much smaller, small enough that one could reach Asia more easily by heading west.

-- The phases of the moon aren't due to the shadow that the Earth casts on the moon. They're simply due to viewing the moon, lit on one side, from different directions. The Earth's shadow is visible on the moon only during lunar (as opposed to solar) eclipses. Although you're right that the ancients were aware of this.

Thanks, Jake!

-Jay

<nerd>meridians.</nerd>