Youta Mottenai
Member
I like this bit:Dax01 said:
-
Hey, guest user. Hope you're enjoying NeoGAF! Have you considered registering for an account? Come join us and add your take to the daily discourse.
Space: The Final Frontier
- Thread starter Windu
- Start date
Windu: Those shots of STS124 are incredible.
Hey man, I'm here to educate. I'm just glad that it's appreciated. I love this stuff. Just keep in mind that I'm not an expert or anything, but I'll do my best. So hell, keep the questions coming.Machado said:
I worked there doing my undergrad as a computer science major. Once I graduated in the fall, I decided to move home for a little while.Quazar said:
I'm not exactly certain what planet this is, but this was taken by yours truly during dawn with the sun glows turning from blue into orange. I'm assuming this is either Mercury or Venus.. I figured it was Mercury because it honestly wasn't that bright in the sky compared to what Venus can provide, and the fact that it was right near the horizon where Mercury is only ever really seen without a telescope during sun rise and set.Machado said:
Here are some images from far away looking at Earth.
^ This has already been posted but it deserves to be posted again. It was taken by NASA's Voyager 1 spacecraft on February 14, 1990. 4 Billion miles away. We are only 0.12 pixel in size in this picture. Space is big, veeeeeerrrrryyyyy big.
^ another picture that has been posted, but look!
^Earth!
This photo was taken by Cassini, 1 billion miles from here.
^ ESA's Mars Express captured this image of Earth and the Moon on July 3, 2005.
^ Earth from the surface of Mars. Another planet! Isn't that awsome! btw it was taken by NASA's Mars rover Opportunity on April 29, 2005.
^ I'm sure this has been posted before because its one of the most famous pictures that man has taken. From the Apollo 8 mission.
Earthrise > Sunrise
Taken by the Japanese Kaguya spacecraft.
^ and this photo was taken by NASA's Galileo spacecraft in 1992 when it was on its way to Jupiter. Its not to scale though.
^ This has already been posted but it deserves to be posted again. It was taken by NASA's Voyager 1 spacecraft on February 14, 1990. 4 Billion miles away. We are only 0.12 pixel in size in this picture. Space is big, veeeeeerrrrryyyyy big.
^ another picture that has been posted, but look!
^Earth!
This photo was taken by Cassini, 1 billion miles from here.
^ ESA's Mars Express captured this image of Earth and the Moon on July 3, 2005.
^ Earth from the surface of Mars. Another planet! Isn't that awsome! btw it was taken by NASA's Mars rover Opportunity on April 29, 2005.
^ I'm sure this has been posted before because its one of the most famous pictures that man has taken. From the Apollo 8 mission.
Earthrise > Sunrise
Taken by the Japanese Kaguya spacecraft.
^ and this photo was taken by NASA's Galileo spacecraft in 1992 when it was on its way to Jupiter. Its not to scale though.
Apologies for the delay. It's been a busy weekend for me.
See this image for what is probably a better view:
http://www.jsc.nasa.gov/history/jsc40/gallery/lores/AS11-40-5875.jpg
http://en.wikipedia.org/wiki/James_Webb_Telescope
http://www.iht.com/articles/2008/05/14/news/vat.php
In their current state? Probably not. Early on though, that's basically how the solar system was formed and even a bit later, objects collided quite "frequently". Uranus, for example, rotates on an axis almost perpendicular to ours (and all the other planets in the solar system) and the best explanation is that it collided with some large object.Machado said:
I don't think so. I could be wrong on that, though.
A lot of that really white look is because of how much light it reflects. What you're seeing though, is just regolith, which is blend of dirt and dust. That's just the colour of it.
See this image for what is probably a better view:
http://www.jsc.nasa.gov/history/jsc40/gallery/lores/AS11-40-5875.jpg
In Mars' current state? Nothing that I can think of. There's no food, as far as we can tell. The atmosphere isn't breathable by most types of creatures. There might be a bit of water, but if there is, it's in very small quantities and probably frozen.
Yep. The James Webb telescope will go up sometime in the future:
http://en.wikipedia.org/wiki/James_Webb_Telescope
It would take too long to travel for it to make any appreciable difference. I'm also surprised that you think that hubble images have been blurry. I'd get into a discussion about resolution, magnification, field-of-view, etc., but I've got to get going soon to a soccer game.
Yep. We're going to collide with the Andromeda galaxy in about 5 billion years (although our star will probably die out around that time).
Hoo boy. The universe is infinite, but the observable universe is something like 90 billion light years across. There's a lot more to this, but I don't even know where to start, heh.
If there's nothing for light to reflect off of, then you just won't see anything.
Although it's not a papal statement, the Vatican's astronomer didn't seem to have a problem with the possibility of it:
http://www.iht.com/articles/2008/05/14/news/vat.php
I'll try to dig one up. I'm pretty new at astrophotography, so they're not the best, heh.
This is really beyond my realm of expertise, but it would depend on the type of bomb, I think. Anyway, assuming it could explode, my guess would be that it would be a little different. There would be no pressure wave (as there is no atmosphere to displace), but the actual energy would still hit you in the form of particles.
Imagine you are an insect on a beachball. Your existence is a two dimensional plane in a three dimensional space. You can travel forever in any direction [except up or down, which for the purposes of this analogy you can't reach] and yet the ball is not infinite. Extend the analogy so the beachball's surface is a three dimensional plane in four dimensional space, and you have the gist of it.Machado said:
Right, unbounded but finite? Or something like that? I remember someone using that to describe it (my astrocred is going right out the window, here). It's been awhile since I've read A Brief History of Time, which is basically the only way I can wrap my head around most of this.Sir Fragula said:
Laurentius
Member
That's one of those almost philosophical difficulties. Spatially speaking, our minds can't comprehend either an infinite or a finite universe. Just the nature of infinity causes troubles, naturally. And a three dimensional finite universe leads us to other concerns, such as what happens if you reached the end. You know, how could there be an existence of "nothing" because by the fact that it does exist qualifies it as "something".
That's a good analogy, but it isn't entirely satisfactory. To maybe make things a bit more clear, try to imagine the beachball as the earth. The surface of either object can be thought of as a two dimensional plane in three dimensional space. In other words, you can determine the location of any point on the surface by just two numbers: in the case of earth, its latitude and longitude. So while the surface of the earth could be thought of as two dimensional, it's imposed upon a three dimensional world where the factor of height is added to the length and width. In other words, to find the position of something in three dimensional space you need an additional number. Basically, you need another number to know where it is in relation to the ground.
So, imagine a two dimensional creature who lives on surface of the beachball or the planet. Being two dimensional he has no ability to move through the third dimension. So his possible paths are limited to what you could draw with a pen on a piece of paper, or a graph. For the sake of this analogy, you could imagine "unfolding" the beachball or whatever sphere you're thinking of, into a flat surface. (I know that doing that doesn't really work [like the way maps have to be distorted] but just bear with me.) So you take that two dimensional flat piece of paper or whatever and fold it back into a sphere. You've taken something two dimensional and essentially "wrapped" it through three dimensions.
So, we can define the surface of this sphere as the two dimensional creature's universe. He would move through it never suspecting that his universe is actually contained within a three dimensional sphere. His path through the universe would just be like that pen line on a piece of paper. He would never know (but he might suspect if he was a philosopher or a theoretical physicist!) that he's really twisting and turning around a planet.
Okay, so our creature decides to explore his universe one day, because he has the same questions about whether it can be infinite or not. He begins at the prime meridian and travels exactly north. Eventually, he goes far enough that he eventually reaches his starting point again! This is sure to be quite shocking for our poor two dimensional adventurer! He might conclude that the universe is indeed finite. There certainly appears to be a finite amount of matter, since he managed to see it all. So he thinks "gee, the universe appears to be a circle!". But this comes with its own problems. If his universe was an infinitely long line, with an infinite amount of matter, he'd arguably have less -- or at least very different -- problems. He'd have no reason to suspect something outside of his own universe.
Now here's where things kind of come together. He concluded that his universe appears to be a circle. But that's him picturing his two dimensional universe depicted in a one dimensional plane. He would begin to use the same logic we have been. A one dimensional creature living in a one dimensional world could be superimposed into our creature's two dimensional universe. (It's one dimensional, because his position in it can be calculated by a single number: it's just the x axis on a graph.) He imagines the 1D creature going on the exact same journey he just did. The 1D creature would be unaware, at first, that his universe exists in a vastly larger one with an added dimension, one that could contain a large (maybe infinite) number of other, distinct, one dimensional universes.
This reasoning shocks our two dimensional creature. His journey has led him to the conclusion, that yes, his universe appears to be finite. There is a finite amount of matter and space. But, going by his deduction using a one dimensional creature, he realizes that there may be something outside of his universe. The third dimension? His two dimensional mind would struggle with comprehending what a third dimension would entail, but he may be able to create models of it in his two dimensional world, such as a drawing of a cube. Eventually, he's likely to come to the conclusion that his universe is wrapped around a third dimension! So...his "universe" is certainly finite. But there does exist something beyond it. It doesn't ever actually "end", according to him. In fact, he may come to a theory of multiple universes, which would be equal to the number of spheres out in our three dimensional space. (And this is where the analogy has some weaknesses, because it only could really apply to spheres, which certainly aren't the only three dimensional objects with a two dimensional surface that we have, but they lend themselves best to this thought process.) He may be most interested in these other universes, but it's also possible he'd wonder about the third dimension. He'd have no clue about the wonders there!
*takes a breath*
Okay. So we take this all into our good ol' three dimensional space, and back to the beachball analogy. Some physicists use this type of reasoning to hypothesize that if you were to travel in a straight line long enough you'd end up back where you started (although, "where you started" could have several definitions). This would lead us to the same conclusions as our 2D friend, that our universe may be finite in space, but it exists wrapped around a higher dimension! This same type of reasoning can be used to hypothesize other universes, that we could only reach by accessing the dimension above our current one. It's hard for our minds to comprehend a fourth dimension (and I'm a bit uneasy about saying fourth dimension, which I'll touch on in a bit) but we can create models of it, such as a tesseract. While we may be interested in other universes, maybe we should be more interested in the fourth dimension, if it can be analogous to our 2Der's plight! Imagine the amount of wonder and variety and possibilities there are in a three dimensional world over his two dimensional world. What might be possible in a four dimensional world?
*head asplodes*
Okay, but this does have a few problems, and is likely not to be true. (The popular physics theory right now is String Theory, which takes an entirely different approach. I don't exactly subscribe to the theory, but it's important to note that there are multiple ways of approaching theses subjects.) For instance, we've completely failed to take time into account here. Once we do throw time into the equation, things get a bit sketchier. Time is often considered the fourth dimension, but it's distinctly different from the other three. It appears to be non-spatial (meaning, not like up or down or left or right) and linear. Maybe we shouldn't define time as a dimension, but this type of thing is essential to Eintein's general theory of relativity. Basically, according to that theory, space and time are intertwined (the spacetime continuum) to form our universe and each is dependent on and affects the other. This leads to lots of interesting things, but we won't really go into them here. So, in that sense, our universe could already be thought of as four dimensional, where one dimension is screwy and makes no sense in relation to the others.
That kind of throws a wrench in some things.
(Of course, Einstein's general theory of relativity has its own holes, particularly when related to the subatomic, where it just doesn't work. So something else may be discovered that creates a better model and supersedes Einstein's. Physicists are trying to find a "grand unifying theory" that basically explains how everything works, or at least a quantum theory of gravity that reconciles Einstein's general theory of relativity with quantum mechanics.)
So yeah, this is really just scratching the surface of things. The beachball hypothesis may or may not apply to our universe, but it's fascinating. And it's a great way to imagine our universe as being both finite and infinite.
Anyway, I'm sure if any physicists come in here they'll be able to point out lots and lots of inacuraccies in this post. I'm not a physicist, it's just sort of a hobby of mine.
Laurentius
Member
Honestly, I think I'm just terrible at explaining things.
And I ramble way too much. Really, as to your original question, I think Sir Fragula's beachball answer should suffice as a way to imagine a finite universe. Which, whether or not it's actually true, it's a really interesting thought experiment!But yeah, I kind of left astronomy and went on a big physics tangent there. =\
http://www.youtube.com/watch?v=fgg2tpUVbXQMachado said:
Like this:Machado said:
Sure! But I don't think going to happen unless some massive collision forces it on us. As for why we spin the way we do, there's some sort of relationship between angular momentum and how the solar system was formed, but I'm a little too tired to remember how it all works.
Ooo, clever ... using a decaying body to start up life on Mars! I know very little about biology, but I would imagine that it would depend on how a body reacts to CO2 (which makes up most of the atmosphere).
I'm sure it would be a mix of: "Holy shit, AWESOME!" and "OH GOD I HOPE WE'RE NOT FUCKED"
It takes time. Lots and lots of time. I think you have to have some sort of affinity for the unknown in order to find any enjoyment in this field. For me, it's always been about learning more and knowing that there's no way in hell I'll ever learn it all.
I was giving an observatory tour to some diplomats who were touring the campus and had this conversation:
<Diplomat Woman> I don't like these places.
<Me> ... high places? (thinking the steps were scaring her)
<DW> No, no! Astronomy places. They make me feel so insignificant.
<Me> Well, that's part of why I love working here!
<DW> *funny look*
Some people just don't get it, I guess.
Nope (or at least: most likely no). All those stars are stars, unless they're planets (Venus, Mars, Jupiter, Saturn are possibilities). Few galaxies are even visible with the naked eye. Andromeda is, and you need to know exactly where to look and how to look for it and when you see it, it's a faint fuzzball. The problem with galaxies is that even though they are filled with billions of bright stars, they're so distant that the light becomes dimmed by interstellar medium (i.e., space dust).
The Hubble Ultra Deep Field:
A higher res version can be found here:
http://en.wikipedia.org/wiki/Hubble_Ultra_Deep_Field
Here's what I had to say about it in the beginning of the thread:
Aside from the few stars you see in the foreground, just about everything in that image is a galaxy, down to the tiniest point. This makes up some 10'000 galaxies and the image is roughly one thirteen-millionth of the total area of the sky. The most distant light that you are looking at is 13 billion years old. For those not keeping score, that places the universe at approximately 800 million years old in this snapshot. That's pretty much the nanosecond after the sperm hit the egg in human terms.
Ask questions, read books, take a course on it, visit an observatory, etc.
Of course, that's all easier said than done. I wish you could give you some direction into some form of light reading. Maybe try some astronomy-related magazines? There's a whole bunch of stuff to this, and it's pretty daunting at first. Most of it, I just learn as I go, but I'm not even sure how I developed my general understanding of the field. Years of interest, I guess. Still, you've got the curiosity, so I think that's a great start.
AndersTheSwede
Member
So glad to see this thread breathing again.
I posted this before, but it's so god damn sci-fi esque amazing I have to repost it.
Indeed, also the leading hypothesis for the formation of our Moon is a collision with a proto planet when Earth was still molten.
Nowadays though the orbits have stabilized (or if they didn't those planets are gone.)
I posted this before, but it's so god damn sci-fi esque amazing I have to repost it.
fallout said:
Indeed, also the leading hypothesis for the formation of our Moon is a collision with a proto planet when Earth was still molten.
Nowadays though the orbits have stabilized (or if they didn't those planets are gone.)
Lost Fragment
Obsessed with 4chan
Someone should make an official thread of awesome physics stuff.
Honestly? I'd recommend a pair of eyes and a star chart, heh. Hubble has kind of spoiled us into thinking that everything we see in threads like these are easily viewable outside. For instance, that picture of the HUDF will never, EVER be visible with just a regular telescope.Machado said:
However, having a look at craters on the moon through a small scope is a really cool experience, as is seeing multiple star clusters in a single field through a pair of binoculars. Still, even these simple tasks can be difficult in the realm of amateur astronomy. So, see if you can find constellations first and then come back to me and we'll talk. The absolute WORST thing one can do is buy a telescope right off the bat. It usually proves incredibly difficult to use and people become dejected and give up.
That, is an excellent question. Mass is the biggest factor, as you need to have enough gravity in order to pull the gases in. Also, the moon does actually have an atmosphere, but it's just very thin. The planet Mercury is similar in that it has very little atmosphere. On the other hand, other moons, like Titan are large enough to have an atmosphere.
Well, it's because of the high velocity and the friction caused by entering the atmosphere. Remember, they're coming from outer space where this is ZERO atmosphere; so the change at that velocity is quite dramatic.
If they could (and I don't think that they can ... I mean, the atmosphere actually acts as a breaking mechanism), it probably wouldn't happen, no.
There's no good point of reference to show you how fast you're going and all the good non-visual indicators of speed on Earth (wind, pressure, etc.) are all contained within the planet.
It took me a really long time to come up with an answer for this one. First off, think of a helicopter for this situation. As the helicopter hovers, it has to displace the air, which is moving along with the earth as it rotates. So, as the air moves, so does the helicopter (even though it's hovering).
I hope I got that right and that it makes sense.
Youta Mottenai
Member
SenseiJinx said:Honestly, I think I'm just terrible at explaining things.
But yeah, I kind of left astronomy and went on a big physics tangent there. =\
There´s this video from Carl Sagan who might help to visualize the ideas in your post:
Carl Sagan (is Awesome and) Explains Tesseracts
Inside the Coma Cluster of Galaxies
Click for Bigger Image
Evolution of the NASA Spacesuit
Click for Bigger Image
NASA Awards Contract for Constellation Spacesuit for the Moon
The Constellation Program mission requires two spacesuit system configurations to meet the requirements of Orion missions to the space station and to the moon. Configuration One will support dynamic events such as launch and landing operations; contingency intravehicular activity (IVA) during critical mission events; off-nominal events such as loss of pressurization of the Orion crew compartment; and microgravity EVAs for contingency operations. Image Credit: NASA.
Link
Configuration Two will build upon Configuration One and will support lunar surface operations. While preparing to walk on the moon, the astronauts will construct Configuration Two by replacing elements of Configuration One with elements specialized for surface operations. Image Credit: NASA.
Evolution of the NASA Spacesuit
Heh, that's pretty cool. I've always wanted to visit NASA and totally geek out. I know the program has tons of issues (many of which I'm quite vocal about), but I'm pretty sure I'd ignore all of that completely while I was there.SonnyBoy said:
Pfft. It's not ignorant in my eyes if you're asking.Machado said:
Well, regolith is just a blanket term for: "The blanket of soil and loose rock fragments overlying the bedrock." Now, obviously, there's no soil on the moon (which would imply some sort of organic material), so we're just talking about dust and such. But yeah, it would survive. We've got a few tons of Moon regolith sitting around at NASA.
That picture I posted came from a NASA probe called Clementine 1 (http://en.wikipedia.org/wiki/Clementine_probe#High-Resolution_Camera_.28HIRES.29). The USSR was the first to photograph it back in 1959.
Well, they see a very near horizon. See here: http://www.apollo-projekt.de/images/AS12-47-6897.jpg
If it were heated during the lunar day (which gets up to boiling), it would evaporate. That said, there's some evidence of frozen water on the north and south poles of the Moon.
Well, Hubble has a diameter of 2.4m and 4.5m² of light-collection area. James Webb will have a diameter of 6.5m and 25m² of light-collection area. So, uh ... it'll be a pretty sizable difference. And the best part really won't be the resolution (sharpness) improvement, but the fact that it'll be able to see farther with greater ease, thanks to the increased light-gathering capability.
It's been theorized, sure, but no evidence has really been provided of it (to my knowledge, anyway). We know that where there's water, there's a strong possibility of life. As such, that's what we're going to keep looking for.
Laurentius
Member
Youta Mottenai said:
Dude, that was awesome. Carl Sagan is great. That really helps you visualize the idea of a tesseract.
I guess a much more succinct version of my previous post would be that it's possible that the universe is indeed finite -- a finite amount of matter and space -- but that it doesn't have an "end", per se. According to the beachball hypothesis, there isn't an edge that you could reach and fall off. It's possible that the universe is akin to a ball, and that if you traveled through it far enough you'd end up back where you started. Which may or may not be possible, but it's very interesting, and helps give a possible answer to those cyclical thoughts about the nature of the universe.
Yeah, I've got to echo this comment! It's been awesome. I don't know a whole ton about space, and this has been very enlightening. It's sort of bringing me back to those days when I was a kid living in the country, and the sense of wonder I would get every time I looked up into the sky, and everything I wondered about it. Unfortunately, when we moved to a city with light pollution, that kind of fell off. The curiosity was still there, but not with the same intensity.
*remembers lying on the grass on summer nights just staring into space and thinking*
Warm fuzzy time!
Crazymoogle
Member
Machado said:
Well, there's the asteroid belt between Mars and Jupiter, which has an awful lot of junk orbiting the sun. One of those things is Ceres, the 3rd dwarf planet (the others being Pluto and Eris). It's not really a planet, per se...just a really big, fairly rounded rock stuck in the belt and not really able to affect the other junk floating around.
Farther out (ie: pluto range) there is the Kuiper Belt, which is filled with objects (some still undiscovered, I imagine) including some of plutoid size, like Sedna, Quaoar, and a few larger but not officially named ones. I think 2005 fy9 is the next candidate for dwarf planet status? It's pretty big but lacks any moons of its own so far.
Anyway, aside from scientific advancement - gravity perturbations and telescopes and whatnot - a lot of the trouble finding places like Eris has been that their orbits tend to be really wacky. If you imagined the traditional 8 planets to all have orbits on a flat plane (and I'm being rough here, that's not the case), their orbits look roughly like lines from the side. The orbit of Eris would look like an ellipse from that same angle...not exactly what astronomers would typically be looking at.
There are eight planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. There are three dwarf planets. Ceres, Pluto, Eris.Machado said:
There are a lot of asteroids. Those in the asteroid belt, those in orbits by Jupiter, and others I forget the term for.
There are a tonne of comets, both inside the main solar system and orbitting many, many Earth-orbits from the sun in the Oort Cloud.
I don't even want to bust out the math on that one, so I'm going to say no. And besides, any significant change in our orbit would affect the temperature of our planet.Machado said:
Not a clue!
They would have waited to die, or tried to resolve the problem until they died. There was no rescue mission planned (although, some further reading led me to this: http://www.astronautix.com/craft/gemelter.htm). This is pretty much why they recruited military test pilots for the early space missions. And this is a complete side-thought I just had ... I think being an astronaut was probably safer than being a test pilot (statistically, anyway).
Crazymoogle and Sir Fragula covered this quite nicely.
Well, it's moving away at a rate of 38 mm per year. Our Sun will explode in 5 billion years. So, in that time, assuming nothing else happens, the moon will have moved away by about 190 000 km (still orbiting, remember). It's average orbital distance is around 400 000km. So, it's orbital size will have increased by about 50% over 5 billion years. This will do things like affect tides (and I think the moon's orbit will eventually stabilize anyway, since tides are what's causing this), but still, we're talking about 5 billion years. I'm betting humans won't even be around by then (as NeoNeoNeo.....NeoGAF laughs at me from the future). And our Sun will be dead then, anyway.
Yep. Although, I find that the planets can almost be too bright at times, leading to a lot of bleeding. Some say it's almost best to view them during twilight. Here are my thoughts on the planets:
Mercury: I've never even seen it through a telescope. Got up one morning to see if I could see it, but that was it.
Venus: Looks like a bit white ball, but has phases like the moon. Sometimes you'll see some really neat colours, but that's mostly an atmospheric effect.
Mars: Looks like a fuzzy, ugly red thing. I've never understood the appeal, even under the best of conditions. But hey, to each their own.
Jupiter: Beautiful, especially when you can make out the gas bands. The 4 largest moons are easily visible and kind of a treat.
Saturn: Stunning. The rings are an incredible sight. The best planet to view and quite possibly one of the most beautiful objects in the entire night sky.
Uranus: Kind of a greenish/bluish fuzzball. Hard to find, but neat to see.
Neptune: Similar to Uranus, but even harder to find. I've actually seen its moon Triton, which ranks as one of my all-time favourite astro-related accomplishments.
Battersea Power Station
Member
By the way, the Large Hadron Collider should be producing collisions soon.
http://en.wikipedia.org/wiki/Large_Hadron_Collider
Many physicists feel it's an important step in forming a Grand Unification Theory. Either way, we'll find out stuff about our universe.
http://www.ted.com/talks/view/id/253
My underwear is colliding with a Large Hardon.
http://en.wikipedia.org/wiki/Large_Hadron_Collider
Many physicists feel it's an important step in forming a Grand Unification Theory. Either way, we'll find out stuff about our universe.
http://www.ted.com/talks/view/id/253
My underwear is colliding with a Large Hardon.
PrivateWHudson
Member
This is great stuff! I'm still trying to wrap my head around 3 sphere and tesseract, but that Sagan video stops right when he's getting to the good stuff. If you drop a cube into flatland, it would look like a square or rectangle depending on how it's rotated, and a sphere would look like a circle. So would a tesseract dropped into our world just look like a cube? If so, I still can't wrap my head around what the 4D shape would look like.
Okay, on to my question. The Bad Astronomy guy says that no matter which way we look, the universe is expanding outward at about the speed of light. Outward being a relative thing...so no matter where you observe the expansion from, stuff is moving away giving the universe no center...at least not a center in this dimension.
-So why doesn't Alpha Centauri get one light year further away each year? It's only 4+ light years away, but obviously older than four years old.
-Does gravity slow the expansion in a galaxy?
-So when they say that the universe is expanding, are they only talking about galaxies?
-Are other galaxies at least as far away as they are old? Is a galaxy that's a billion years old at least a billion light years away?
I'm guessing that when they say the universe is expanding, we are moving at the same rate with everything else, that's why things don't get a light year further away each year. But since everything is expanding "outward" from us, then we are also moving outward in all directions at the same time. And THAT is just messed up.
Okay, on to my question. The Bad Astronomy guy says that no matter which way we look, the universe is expanding outward at about the speed of light. Outward being a relative thing...so no matter where you observe the expansion from, stuff is moving away giving the universe no center...at least not a center in this dimension.
-So why doesn't Alpha Centauri get one light year further away each year? It's only 4+ light years away, but obviously older than four years old.
-Does gravity slow the expansion in a galaxy?
-So when they say that the universe is expanding, are they only talking about galaxies?
-Are other galaxies at least as far away as they are old? Is a galaxy that's a billion years old at least a billion light years away?
I'm guessing that when they say the universe is expanding, we are moving at the same rate with everything else, that's why things don't get a light year further away each year. But since everything is expanding "outward" from us, then we are also moving outward in all directions at the same time. And THAT is just messed up.
The most common analogy is to imagine the universe as unbaked dough and the galaxies within the universe as raisins in that dough. As the dough rises (universe expands), the raisins (galaxies) get farther away from each other, but any of those raisins can be seen as a central point with respect to the other raisins.PrivateWHudson said:
I'll answer your third question first, since it's just easier in terms of this discussion:
Gravity effectively stops the expansion in a galaxy. As another analogy, you're not ripped to shreds by tidal forces, but they're clearly have a strong effect here on Earth. Try to think of it like that.
Gravity holds it in its orbit around the galaxy.
I'd say for the rest of your questions, I'm going to have to defer you to here:
http://www.astro.ucla.edu/~wright/cosmology_faq.html#ct2
Cosmology is not my strongest area. Maybe someone else can chime in.
thebagofsand
Member
Thanks guys, great thread. I've always had a fascination for Space, don't really know much about it :\ but hey the pictures are amazing.
You can determine a planet's size using some fairly basic trig.Machado said:
Measuring the size of stars is something that is done by analyzing its spectral type and then inferring its size from that. There's basically a connection between a star's mass, spectral type, temperature, etc., so once you have part of it, you can figure out the rest.
The planet pictures were most likely taken by various probes. I should probably recognize them and know which ones were taken with what, but I'm too lazy to go around and compare. Any of those stars that isn't the Sun is just a mock-up.
Crazymoogle
Member
Just a heads up; we've seen some great mars photos, even in this thread, but this link has some particularly vivid resolution shots from the latest mission.
1. Well, providing you were invincible I think Venus would be pretty interesting as one of those places that you simply just couldn't look around otherwise. I think Venus is a pretty interesting place; if the climate (and I imagine a bit of the geology) could get under control, it would be a far more hospitable place than Mars. (Note: Mars actually has a more promising magnetic field though.)
2. Either tidal effects causing slowing, or a massive impact event. (Even Earth is gradually slowing down; our day was apparently 23hrs around the time of the dinosaurs.) Venus has a further problem in that its rotation is so damn slow.
3. Not really in the traditional sense. It has various spheres of influence - heat, magnetics, radiation and so on - but obviously is way too hot to support the things we consider to be atmosphere. It's full of heavy elements, but short of wacky star trek technology we won't be getting close to the Sun anytime soon.
4. I'm sure somebody has a better answer; but simply put, the diameter and surface area of the Earth are so large that from an individual perspective on the ground, the world appears flat; the actual bend of the planet is obscured by the atmosphere as well as surface features. To make things more complicated, the Earth is not perfectly round; it bulges around the equator.
5. There is talk (and some work) towards a Mars mission sometime around 2030, but the problems are ridiculously massive. Currently, the travel time there is measured in months, not days, there is little or no radiation protection on the way or at the destination, and unlike the Moon, there is an atmosphere to penetrate, so the landing would be difficult. Even communication time would be significantly longer.
I think the last estimate I saw put mission cost at $20 billion?
6. Not sure on the specifics, but this is not the case for all of the planets. Pluto, Neptune, and Eris have a very different interaction than the inner core of the Solar System.
Machado said:
1. Well, providing you were invincible I think Venus would be pretty interesting as one of those places that you simply just couldn't look around otherwise. I think Venus is a pretty interesting place; if the climate (and I imagine a bit of the geology) could get under control, it would be a far more hospitable place than Mars. (Note: Mars actually has a more promising magnetic field though.)
2. Either tidal effects causing slowing, or a massive impact event. (Even Earth is gradually slowing down; our day was apparently 23hrs around the time of the dinosaurs.) Venus has a further problem in that its rotation is so damn slow.
3. Not really in the traditional sense. It has various spheres of influence - heat, magnetics, radiation and so on - but obviously is way too hot to support the things we consider to be atmosphere. It's full of heavy elements, but short of wacky star trek technology we won't be getting close to the Sun anytime soon.
4. I'm sure somebody has a better answer; but simply put, the diameter and surface area of the Earth are so large that from an individual perspective on the ground, the world appears flat; the actual bend of the planet is obscured by the atmosphere as well as surface features. To make things more complicated, the Earth is not perfectly round; it bulges around the equator.
5. There is talk (and some work) towards a Mars mission sometime around 2030, but the problems are ridiculously massive. Currently, the travel time there is measured in months, not days, there is little or no radiation protection on the way or at the destination, and unlike the Moon, there is an atmosphere to penetrate, so the landing would be difficult. Even communication time would be significantly longer.
I think the last estimate I saw put mission cost at $20 billion?
6. Not sure on the specifics, but this is not the case for all of the planets. Pluto, Neptune, and Eris have a very different interaction than the inner core of the Solar System.
Crazymoogle
Member
Hootie said:
Oh, sure. It's peanuts compared to a lot of things in the US budget. The problem is, that's billions more than NASA's current yearly budget, and only 6 years in history can match that number. I think the whole idea of Earth-Mars travel needs development and streamlining - I really believe terraforming needs to happen at some point - but eviscerating NASA would not be the best way to do it.
thelegend69697
Member
This one is one of my favourites, some awesome pictures as well.Antimatter said:
http://www.chapters.indigo.ca/books/The-Universe-And-Beyond-Terence-Dickinson/9781552979013-item.html?ref=Search+Books%3a+%2527universe+and+beyond%2527
If I could visit any planet? I think I would have to go with Jupiter. And by Jupiter, I mean its moon Europa (suck on it, black monolith). Digging around for water and enjoying the sight of this massive gas giant in front of me. I think it'd be pretty neat.
And more realistically, I would give my left nut to visit Mars. I don't know who would want my left nut or what for, but I would honestly do it.
And more realistically, I would give my left nut to visit Mars. I don't know who would want my left nut or what for, but I would honestly do it.
To be fair, the $20 billion estimate would most likely ramp up very quickly. Still peanuts, but ... larger ones. Cashews, maybe.Hootie said:
More answers!Machado said:
I couldn't remember if HST (Hubble Space Telescope) had imaged Pluto or not, but I just spent like ... the past hours going through various HST images. God, I hope STS-125 goes well.
Anyway, this is the best known image of Pluto, taken in 1990:
Unfortunately, the cheaper you go, the worse off you usually are. In fact, going cheap can usually be a waste of money. However, if you're REALLY keen on this (and I still advise against it) ... see if you can find a cheap 3-4 inch achromatic refractor. It'll be decent for planets. Whatever you do, don't just buy one at the department store. They have TERRIBLE optics.
It's basically a result of gravitational force. Two bodies interacting on each other. It's we the ocean rolls in and out.
Of course! Here's the HST from one of the space shuttle missions (STS-82):
Right now, Jupiter is in the constellation Sagittarius, which should be visible to you.
Yep! There was a Russian probe. It didn't last too long thanks to the raining sulphuric acid, but you can read more on it and see images of it here:
http://cseligman.com/text/planets/venussurface.htm
And other Venus mission here:
http://en.wikipedia.org/wiki/Observations_and_explorations_of_Venus
There is ice in the form of CO2 (carbon-dioxide) and there is evidence of water-ice as well.
There are clouds, dust storms, etc. It has an atmosphere, and associated weather. It's just not very hospitable.
Laurentius
Member
Those Venus pictures are really cool. I've never seen a picture of the surface of Venus before.
No rain that I'm aware of, but there is precipitation in the form of frost. Lightning as well.Machado said:
The warmest it gets is -5 °C
I'm pretty sure that the acid melted most of the equipment. I remember reading that some of it had been diamond coated. I can't verify that, though (or at least, be bothered to). Point is, Venus is more inhospitable than Mars, heh.
From Wikipedia:
At the time of its discovery, Huya was the biggest and brightest TNO (Trans-Neptunian Object) yet found. It was found using data collected by at the CIDA Observatory in Venezuela. It is estimated to be 480 km in diameter.
http://en.wikipedia.org/wiki/38628_Huya
Pretty neat discovery, if you ask me.
Yeah, we've got plenty. Most through bigger telescopes than most of us have access to, of course. This was taken with the HST during a close Mars approach back in 2005.
Here's a collection of Mars images that I found, taken by some guy in the Philippines using an 11 inch Schmidt-Cassegrain telescope and a DMK21BF04 camera.
http://astro.christone.net/mars/index.html
Here's a sky chart for your area at the time that I'm posting this.
So, it'll be a little south-west of the Moon.
Crazymoogle
Member
fallout said:
Hmm. Dunno about Acid, but the two big problems AFAIK were:
Temperature (400-500c)
Pressure (90-100 earth atmospheres)
It's kind of like trying to land a probe deep underwater, only all of the water is lava. :lol
One neat atmospheric side effect is that the russian probes that landed on the surface actually jettisoned their parachutes 50km from the ground, and used air-brake techniques for a gentle descent.