The picture of Saturn that Carl Sagan's image came from used to be my desktop wallpaper.  Beautiful and humbling, but lest we be too pessimistic, let us not forget that we're a dot that invented fireworks and space travel and love and Cadbury Mini-Eggs.  (Okay, love was more of a discovery than an invention.)  There's a lot you can do from a dot.  It's more than you could do without one.

That last image is equally astonishing if less personal.  Based on the numbers they give, if you looked up at the full moon and partitioned it into 3600 equal parts, one of those infinitesimal parts would be the size of the chunk of sky represented by that one photograph.  But can someone explain why "the universe, statistically, looks the same in all directions?"  Seems like it should look denser if you look towards the Big Bang than away from it...

Try to listen something called "The Sounds of Space" on Youtube. It's a clip consisting of radio waves sent from various Solar System objects, that were converted to the spectrum of hearing. Almost all are very cold, and disturbing, creepy noises, but the sound of Earth.... it's a really calm, beautiful, soothing hum, with kind of singing... I can't describe it....

http://www.youtube.com/watch?v=5ZYFaEZV-aQ

This is the link to the clip. Tell me how do you like it...

Nanami's Rose Groom wrote:

Try to listen something called "The Sounds of Space" on Youtube. It's a clip consisting of radio waves sent from various Solar System objects, that were converted to the spectrum of hearing. Almost all are very cold, and disturbing, creepy noises, but the sound of Earth.... it's a really calm, beautiful, soothing hum, with kind of singing... I can't describe it....

http://www.youtube.com/watch?v=5ZYFaEZV-aQ

This is the link to the clip. Tell me how do you like it...

"Music of the spheres" indeed   These sound like something out of a Fatal Frame game, except for Earth, which sounds like something from Myst.  I wonder if they converted the radio waves to audio in the same way for each object, or whether Earth's very obvious difference from the others might be because whoever did the conversion chose to make it that way.

I'm nit-picking, but unless they're counting Ceres as a planet for some reason, they mean that Neptune is the eighth most distant planet from the sun.  (Except when it crosses the orbit of Pluto, when it -- actually, remains the eighth most distant planet from the sun, since poor Pluto doesn't count anymore.  )

I'm not sure what exciting things happen in astronomy per se (as opposed to cosmology) these days.  It seems like the discoveries that can be made by observation from Earth have mostly been made, so while we wait for Voyager to hit the heliopause or New Horizons to make it to Pluto all we can do is argue about the semantics of the word "planet" and whether Quaoar is round or not.  It's not like we're going to discover that Earth has a heretofore unsuspected second moon, or that our existing moon is no moon but is in fact a space station.  Apart from looking for comets on a collision course with Earth, what can you do with a telescope anymore that's exciting and novel to someone who doesn't care that much about astronomy?

BioKraze wrote:

satyreyes wrote:

It's not like we're going to discover that Earth has a heretofore unsuspected second moon, or that our existing moon is no moon but is in fact a space station.

Dahak much, satyr?

It was supposed to be a silly Star Wars joke, but apparently I tapped into a broader tradition than I realized!  I'd never heard of the Dahak, and now I learn of a revolutionary book by Don Wilson entitled Our Mysterious Spaceship Moon.  (Warning: linked website contains the sentence "The fact that the Moon is hollow does not necessarily mean that it is a spaceship fashioned by Aliens.")

I think in Gurren Lagann the moon turned out to be a giant alien robot as well.  That would get people interested in astronomy.

Didn't they recently find the first earth-sized planet outside our solar system? I thought that was pretty exciting, even if it was too close to the star to support life.

satyreyes wrote:

But can someone explain why "the universe, statistically, looks the same in all directions?"  Seems like it should look denser if you look towards the Big Bang than away from it...

From your question, it seems that you imagine that at the time of the Big Bang all the matter in the universe was concentrated in a single point in otherwise empty space, and that it then exploded outward to fill up a larger and larger ball in the emptyness.

That's certainly an intuitive picture, but what the actual theory describes is something much weirder! It says that matter has always been homogeneously distributed in space, but the density of matter is getting lower (the average distance between galaxies is increasing).

Let's make an analogy. Theory says that the universe is either infinite or finite without boundary. In fact, evidence seems to point to the former, but the latter case is easier to visualize, so let's go with that. It being finite without boundary means that, if you were to travel in a straight line far enough, you would get back to the point you started. This is very much like the surface of a sphere (but with an extra dimension) -- or the surface of a balloon! So imagine a balloon surface on which someone has drawn lots of little dots (galaxies) with a pen. If you blow up the balloon, all the points gets farther away from each other, but there is no point of the surface which is at the center of the expansion. It is "space itself" (the surface the dots are located on) which is expanding.

Last edited by Pfft (05-16-2009 08:44:20 PM)

Pfft wrote:

satyreyes wrote:

But can someone explain why "the universe, statistically, looks the same in all directions?"  Seems like it should look denser if you look towards the Big Bang than away from it...

From your question, it seems that you imagine that at the time of the Big Bang all the matter in the universe was concentrated in a single point in otherwise empty space, and that it then exploded outward to fill up a larger and larger ball in the emptyness.

That's certainly an intuitive picture, but what the actual theory describes is something much weirder! It says that matter has always been homogeneously distributed in space, but the density of matter is getting lower (the average distance between galaxies is increasing).

Yes, you describe how I imagine the Big Bang, but I don't see how that's inconsistent with matter being homogeneously distributed in space, with the density decreasing as space expands.

Let's make an analogy. Theory says that the universe is either infinite or finite without boundary. In fact, evidence seems to point to the former, but the latter case is easier to visualize, so let's go with that. It being finite without boundary means that, if you were to travel in a straight line far enough, you would get back to the point you started. This is very much like the surface of a sphere (but with an extra dimension) -- or the surface of a balloon! So imagine a balloon surface on which someone has drawn lots of little dots (galaxies) with a pen. If you blow up the balloon, all the points gets farther away from each other, but there is no point of the surface which is at the center of the expansion. It is "space itself" (the surface the dots are located on) which is expanding.

I'm not understanding the metaphor here.  The universe has boundaries, which I guess can be envisioned like a balloon, and as I understand it those boundaries are expanding at more or less the speed of light.  But the universe is not just that outermost boundary; it's all the space inside it.  It's a complete sphere, not just the surface.  So, because it's a sphere, the universe has a "center" -- it's the point farthest from any boundary, which is presumably pretty close to the spot the Big Bang once occupied.  If you blow up a building and then stand somewhere in the rubble, you'll see more debris if you look towards where the building used to be than if you look in the opposite direction.  I still don't understand why the same doesn't apply to universes.

Stormcrow wrote:

In Pfft's analogy (OK, probably not, but I have no idea who thought of it first), the universe is in fact only the surface of the balloon. If I'm following correctly, the point is that in the Big Bang, the universe we know today didn't expand into something that was already there, everything was just tiny. Being so small, with everything so closely packed, made for properties that are very different from the ones that prevail today. Since the Big Bang, EVERYTHING has expanded gigantically. Not into otherwise empty space, because space has expanded too? Strange stuff. But that being the case, if the universe were infinite, there would have been no locality where the Big Bang happened. It happened everywhere.

Am I on the right track here? This doesn't seem to gibe with what Giovanna said.

I'm sorry to be so dense, but I'm still not following the "surface of the balloon" thing.  Whether the universe is expanding or just getting larger, it's a sphere.  Spheres have centers and you see more when you look towards them.  If you are standing on a big balloon you will clearly see more balloon by looking down than by looking up.

Last edited by satyreyes (05-16-2009 11:04:12 PM)

Deleted because I posted in a bad mood and without thinking about it properly.  Sorry!  I'll try again later.

Last edited by satyreyes (05-16-2009 11:50:49 PM)

Sorry it took so long for me to post in this thread, I've been trying to get my notes together. Allow me to dumb the place down a bit for new-bloods like me, eh? hurr hurr hurr :B

Most is cross-posted from my LJ, because I am a lazy kind of gal. And yeah, most of this stuff y'all probably know.

*Planets also do not twinkle/twinkle significantly less than stars. Also because they are closer, and are not affected as much by the atmospheric turbulence. [One way to look for the "seeing" is to look across the horizon. If the stars along the horizon twinkle significantly more than the ones above your head, the seeing/turbulence is "good". If the ones above your head are also twinkling significantly, the seeing/turbulence is "bad".]

*All planets [and also the moon] follow an imaginary line called the ecliptic. "Since the earth is but one of the planets, and since all the planets orbit the sun in approximately the same plane, from our point of view the planets and sun must follow roughly the same line across the sky." [Peterson Field Guides: Stars and Planets, Jay M. Pasachoff, Pg. 10]

*An asterism is a part of a constellation.

*The zenith is the point directly over your head in the sky.

*The brightness of a star is measured in magnitudes. The smaller the number, the brighter the star. [Turns out that I was wrong all along, Sirius is the brightest star in the sky at a magnitude of -1.4, not Polaris. I always thought Polaris was the brightest... I am at a magnitude of 30, methinks.]

*The Big Dipper is close enough to the north celestial pole that it will never set, so it is a circumpolar asterism.

*The Hyades and the Pleiades are both open clusters [also called galactic clusters]; these are locations where 100 or more stars are close together in an irregularly shaped group. [THEY ARE NOT CALLED TRAPEZIUMS OK GAIZ? 8D~]

*Libra, before it was "The Scales", was known as the "claws" of Scorpio. Claws of justice, y/y? [fff whatever it made more sense in my head.]

*Some first magnitude stars include: Regulus, Arturus, Vega, Deneb, Cygnus, Altair, Spica, and Anteres. I have to measure the altitude of five of these before the last day of class. I need to get a full list so I have more stars to choose from.


Hnurk hnurk sorryyy~



ETA: Also, when I was in the Vertigo Dome, we took a look at Saturn [was it supposed to be mint-green?] and  the Sombrero Nebula. *shakes maracas* Well, everyone else could see the Sombrero Nebula. I was too short, so I couldn't see all the way around the eyepiece correctly. :<

Last edited by Lady Nilamarthiel (05-18-2009 02:23:24 PM)

Concerning the uniformity of space, my explanation and Pffts do not actually disagree, we're just explaining it a couple different ways. (I might clarify later, slipping this by at work.)

Habitable space is the surface of the balloon. It's a sphere in that it expands from the center of the Big Bang, but because the 'space' inside the balloon is not occupied with matter, it doesn't really count, although at earlier stages it was the habitable space, as the balloon inflated. A lot of different theories here, again pick one you like. One common idea is that habitable space, ie what we see when we're talking about 'uniformity in all directions' is decided by the right cooldown temp. Within the balloon's surface, it's cooled down too much, beyond it, nothing exists yet or it's too hot. If you think of the universe as a huge solar system, the balloon surface is the Goldilocks zone where matter can exist. It's uniform in all directions (where you'd assume stars less sparse if you face the center of the sphere) because our perception is just that small. Looks the same to us because our visible space is a small sphere within that balloon's surface--if you're an atom in that balloon, you're probably surrounded by other atoms the layer visible to you is uniform in all directions.

Now, if you wanna dick around with M theory and such, then because of the structure of space and fancypants shit I'd need to reread books to find the original explanation for, the universe is truly without a border, including the surface, inside and outside of the balloon. IE, you can travel from one 'end' of the universe 'through' the inside of the balloon to the other. Yep.