How they do that by looking at photos far away??

astralliquid · Jul 6, 2005

I am no astronomer..just an average person. Space, universe, aliens always facsinate me. Hope someone kind enough to answer me in layman terms. How the hell do scientists know the ingredient, gases, elements in far away planets just by looking at far away blurry photos? How will crashing into a comet tell us what is inside it just by looking at those photos??? How do they know the other planets are 15 million light years from us just by looking at photos!!??? How do they know the other planets are rocky like us 15 million light years away just by looking at photos!!??? Thank you for your kind answers.

mooware · Jul 6, 2005

How the hell do scientists know the ingredient, gases, elements in far away planets just by looking at far away blurry photos By analyzing thier light. Although, I think you mean stars here. There hasn't yet, to the best of my knowledge, been a photographed planet. How will crashing into a comet tell us what is inside it just by looking at those photos??? By analyzing the debris. How do they know the other planets are 15 million light years from us just by looking at photos!!??? I don't think there has been anything detected that far away, but you would get evidence of a planet by watching the gravitational tug (wobble) on the parent star, or perhaps by transition of the planet across the face of the star, thus dimming the light detected by us. How do they know the other planets are rocky like us 15 million light years away just by looking at photos!!??? There hasn't been a rocky planet detected at that distance. There is one at 15 light years away. They think it's rocky because of it's apparent size, judged by the wobble on it's parent star.

tfwthom · Jul 6, 2005

Everthing you ever wanted to know about extrasolar planets.......PlanetQuest http://planetquest.jpl.nasa.gov/index.html or 152 other planets and counting....... <div class="Discussion_UserSignature"> www.siriuslookers.org </div>

dragon04 · Jul 6, 2005

"How the hell do scientists know the ingredient, gases, elements in far away planets just by looking at far away blurry photos?" I think that once they determine the approximate mass and orbital period of an exoplanet, scientists can infer what elements would be gaseous at the calculated temperatures that the planet is subjected to by its proximity to the parent star. <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

astralliquid · Jul 6, 2005

Thank you for your response. Whether stars or planets, I am still intrigued by the fact that they can tell so much based on things you cannot physically touch or go near. everything we read about is all based on telescopic images. When you said "By analyzing the debris" so how can you analyze the debris by just looking at the photographs? say for the tempel 1 case for one. Ok.. so it made for sense calculating the distances by watch wobbles.. but the gases?? how do they know by looking at photos?? I know I am dumb to ask these questions when human have such advance technologies...but then a again.. I am just your average guy doing normal things in lives.. I applaud those genius for being able to calculate accurately something so far far away and hit it bullseye.. just beyond my imagination how the hell they manage to pull that off.

mooware · Jul 6, 2005

When you said "By analyzing the debris" so how can you analyze the debris by just looking at the photographs? say for the tempel 1 case for one. Well, it's not just any photograph, the spacecraft carries a set of instruments and the smart impactor. Two instruments on the flyby spacecraft observe the impact, crater and debris with optical imaging and infrared spectral mapping. You can tell what chemicals are present by the color of the spectrum. As is the same with stars and atmospheres of other planets. Here's a link for you. http://www.astro.uiuc.edu/~kaler/sow/spectra.html#absorption You're not dumb to ask these questions. If you don't ask how do you learn?

bobvanx · Jul 6, 2005

>> I know I am dumb to ask these questions when human have such advance technologies...but then a again.. I am just your average guy doing normal things in lives.. Not dumb at all! Humans have been discovering things for ages now. Some of the discoveries from two hundred to five hundred years ago are very "accessible," by which I mean we can grasp them and follow what the person was trying to find out. The pace of discovery has built up, and discoveries have piled on to those earlier discoveries, until nowadays it is quite hard to get a handle on how some of these things could possibly be true. There are a couple of basic assumptions that all scientists make: if something is true here on earth, then it is true everywhere else in the universe, and similar effects follow from simiar causes. For example, if a prism can change white light into a rainbow in the lab, then a rainbow in the sky is be formed by a prism too; in this case, lots of drops of water. A prism would make a rainbow on Mars, or the Moon, or on a planet around a star 100 light years away. Rainbows are really useful scientifically, too. It turns out that if a cloud of gas is glowing, like sodium vapor, it only sends out part of a rainbow. There's no "white." Sodium vapor on Earth glows orange. So we assume that sodium vapor elsewhere in the Universe would glow orange, too. White light shining through cold gas shows just the opposite: for sodium vapor, the orange gets absorbed. So if we look at the light from a star anywhere, and we see orange light, we say it's got hot sodium vapor in its atmosphere. If orange light is missing, than we can say there is a cloud of cold sodium between us and the star. All things reflect or absorb light this way, so by taking photos and measuring what colors we see or don't see, we can make good guesses about what the stuff in the picture is made of.

Saiph · Jul 6, 2005

right, as bobvanx was saying about gases and light: each element, when in a gaseous state (not solid chunks) and has energy flowing through the gas, via light or electricity (free flowing electrons) can emit, and absorb light. As a property of the elements themselves, each element absorbs or emits a very specific pattern of lines. these patterns are called the element's "spectrum" and act as fingerprints. these spectra also vary in specific way under different conditions. Denser gases have broader lines for instance, different temperatures of the gas allow different lines to appear (some lines require more energy than others). By analyzing the pattern, the location, and the shape of the lines, we can determine all sorts of useful information. The big four are Composition (by identifying what patterns are present), Temperature (by identifying what lines for an element are present), and density and velocity (determined by variations in the width/shape of the lines). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

astralliquid · Jul 7, 2005

Wow.. thank you! gave me a better perspective of things now although it sounds like science class years ago which never caught my attention. <img src="/images/icons/smile.gif" /> My knowledge is limited in this area, I don't know what to say..anyway bob was very right to say discoveries are beyond comprehension of normal people these ages.. just hope all the great scientists out there knows what they are talking about and take us to higher levels. The Universe is so interesting!! Hope I am not alone to think it is impossible to tell a great story out of a photo with a few dots of lights. More explaination and links welcome!! Great discovery for me at least.

Saiph · Jul 7, 2005

I actually believe a large amount of current scientific knowledge can be understood by most everyone. anyway, I'm happy to help. If you have any more questions along these lines (or others) feel free to ask. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

astralliquid · Jul 7, 2005

So I am the odd one out eh to know so few? Anyway here's another dumb question I am reading about this.. http://www.space.com./missionlaunches/missions/heliosphere_shock_010706.html If the voyager is so far away, how do we know it is so far away? Does it mean we are still receiving signals, communication from the voyager "that" far away? If that is the case, doesn't that meant alot of possibility for humans to send Spirit & Opportunity to the fartest of the fartest to remotely control it whatever way we like? I am not a science student or an astromoner. just a normal guy you see on the street interested in space stories. so sorry if my questions insulted the intelligence of the experts here.

Saiph · Jul 7, 2005

One aspect of light is that a moving object emits light that is "shifted" from it's original frequency. The voyager spacecraft were emitting radio waves at a specific frequency (so we knew what to dial into). however, since they are moving relative to us, that frequency is shifted to a lower frequency (since voyager is receeded. It is shifted to a higher one, if approaching us). By measuring how much this signal is shifted, we can determine how fast it is moving. Other observations of can tell us how fast the spacecraft is moving from left to right (this left to right motion does not affect the frequency of the signal, as it is not heading towards, or away from us). From this we know where it's going, and how fast it's going. Then, it's a matter of some math. If you know someone is heading north, at 50 mph, where will be be in ten hours? 500 miles further north. Over these distances however, even those just to mars, you end up with a communications delay. The speed of light is really fast...but the distances in astronomy are really big. It takes several minutes for instructions to the mars probes to arrive, and several minutes for their responses (and camera images) to return. It's like trying to do real time instructions through the mail. Such effects can be noticed every day. ever wonder why reporters on TV that are "live via satellite" take so long to respond to questions instead of just looking dumb in the camera for a bit? It's because the signal takes time to go from the cameras, through the electronics, up to the satellite, back down, through electronics again, and finally to the reporters camera. Then it has to come back. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

bobvanx · Jul 8, 2005

>>So I am the odd one out eh to know so few? No, you're the odd one out because you're interested in figuring this stuff out. Most people are happy to abide in ignorance (or in disbelief of and mistrust in "scientists"). Last week's episode of "Lost" is more important to most people than looking up and wondering why a blue star is blue. Like Saiph wrote, nearly all current knowledge is within the grasp of the average person. There's some real esoteric stuff that hasn't yet been translated well so the average person can understand it, but just wait a little and it will be. I have an in-law who was pretty much self-raised. He's a good guy, but there are fascinating holes in his knowledge; no one was there to teach him some things that most of us know. For example, one night he asked, "How far away are the stars?" We told him about the galaxy and the distances involved. His next question was really interesting: "How bright are they, if I can see then from so far away? I thought they were the size of basketballs." So you see, he had already observed that brighter things can be seen farther away. As long as he thought stars were just beyond the atmosphere, that glowing basketball image worked for him. But when we told him the real distances involved, he knew he had to shift one of his preconceptions. He chose brightness; the idea of lots of objects as big or bigger than the sun just hadn't occured to him yet. A note on the "regular guy" stuff: I'm an Art Director, with only a bit above average science training. So the knowledge really is accessible, once you start wanting it.

Saiph · Jul 8, 2005

Right, and while I agree that most people aren't cut out for doing scientific research, that doesn't mean they can't understand a lot of the science. It's really similar to how most people can't be proffesional pianists, but almost everybody can play the piano fairly well...if they take the time to learn. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

yevaud · Jul 8, 2005

Saiph, Buddy! How's the blessed Summer off after Graduation? <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Jul 8, 2005

Summer....off? I know not this concept! I've just finished moving from NE, to Irvine, CA. I've already started diving into a new research project here: A search for low surface brightness, dwarf galaxies in the haloes of "early type" galaxies in an effort to figure out if/why the numbers don't stack up with the cold dark matter model of galaxy formation's predictions. Fun stuff. So far, I've spent a week reading on the IRAF image analysis software and UNIX OS procedures (unix is very interesting btw). Reading, and recovering from throwing out my back moving (well...almost, it's pretty screwed up). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

astralliquid · Jul 8, 2005

Thank you Saiph and bobvanx!!! you guys makes it sounds so easy <img src="/images/icons/smile.gif" /> but really your answers helps me alot trying to figure out why. Question 1 : On the radio wave thing... I know there are delays in sending signal back and fro and it takes a long time to reach, rendering unrealistic to do anything much. But what I am more concern is, at a distane of what, 82 AU?? radio wave can still reach earth???? being a "regular" guy.. it takes me sometime to comprehen the idea of cellphones, radios, wireless network thingy because to me, the idea of our voice, data travelling miraculously from one object to another, still facsinate me! to me, this is just empty space and how the hell this things comunicate!!..ok, I know basic sciences like there are microwave, radio waves, atoms, masses whatever in the air that makes all this possible but still...its emptiness to a human eye...so back to the question...this signals can travel sooooo far??? (between earth and the horizon of the galaxy/universe?) Just like how I always always wonder how the hell a basketball player can shoot from a 3 point line accurately in the loop... the hole is so small and yet it goes in perfectly. Now put the same player 10000 miles apart from the loop..can he still shoot it accurately asumming he has the strength? What am I talking her....thanks anyway.. --------------------------------------------------------- Ok Question 2. I was reading this http://www.mercurynews.com/mld/mercurynews/news/breaking_news/12088473.htm I know Tempel is travelling at a very fast speed. The mothership release the impactor and stay on the side to capture photos.. now this part of the story kept me thinking... "Scientists are waiting for the dust from the larger-than-expected debris cloud to settle before they can get th

yevaud · Jul 8, 2005

I know UNIX well (got a sysadmin. Cert. in it). Command line, command line, command line... Very interesting. Those ancient, "blue" galaxies? <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Jul 8, 2005

You can think of most modern wireless telecommunications as a sophisticated "morse code". If I took a flashlight, and shined it towards you, then repeatedly blocked the light in an agreed upon pattern, we'd be able to communicate. Modern wireless communications merely vary the intensity of the signal (or vary the frequency from an agreed upon value) to do the same thing. The forms of light used (microwaves, radio, infrared, etc) are the same thing we see with our eyes, the only difference is how much energy they have. They normally don't have enough energy to trigger the light sensitive cells in our eyes, thus they are not percieved by our eyes. Now, the beams can have a lot of energy, as a whole, as they put out lots of individual photons. But each photon has only a fixed amount (which is outside the energy range of the human eye). This light goes forever, and does not stop unless something physically blocks it. It will drop in intensity however, as the photons making up the beams spread it out, and make picking up enough photons to reproduce a good signal very hard. Distant spacecraft radio back, but it takes a huge array of radio telescopes (the Deep Space Network) to pick up their signal strong enough to process it into meaningful information. Without this network, we'd recieve the signal, but it would be so mired in noise from other sources it would be meaningless (try hearing someone shout across a crowded stadium). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

astralliquid · Jul 8, 2005

You are very good at this...kept thinking for a while.. thanks

astralliquid · Jul 9, 2005

Can anyone clear my thoughts on question 2 above? This can be made into dummy for astronomers..really good simple answers..

Saiph · Jul 9, 2005

Yevaud: Not those ancient blue galaxies, though the techniques are likely to be similar. We're looking for faint "satellite" dwarf galaxies about galaxy clusters (sorta like the LMC and SMC). The CDM models suggest a certain density of these galaxies, and current observations of the local group don't turn up enough. But local group galaxies tend to be "late type" galaxies, and many wonder if the "early type" galaxies may have more satellite dwarfs... Unfortunately that means we have to look further...for faint things. Not easy. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Saiph · Jul 9, 2005

Your second question: I wish I could answer, but I haven't followed up the mission details much. One thing to remember, it may be going fast compared to us, but so is the comet. That means they may be stationary compared to eachother (like two cars both going 50 mph down the freeway). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

a_lost_packet_ · Jul 9, 2005

astralliquid - Can anyone clear my thoughts on question 2 above? The flyby craft rotated when it passed Tempel 1 and will continue to observe the comet until about the end of this month I think. I am not sure what the seperation speed between Tempel 1 and the flyby craft is. I hope the debris and ejecta clear soon so we can get some good shots of the crater! <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

astralliquid · Jul 10, 2005

Thats my problem of understanding this. how can the flyby observed the comet when the comet is flying so fast? does it has an orbit for the flyby to rotate around it?

How they do that by looking at photos far away??

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