Radio Astronomy Question
I'm new to the world of astronomy and while studying the different forms of electromagnetic radiation (light) I've had a question in my mind that I know is a stupid question but I can't help but ask.... Why is radio astronomy associated with listening? Or is it? All I have ever learned about science comes from the movies and I remember watching "Contact" with Jodi Foster's character sitting with her eyes closed "listening to the stars". I suppose radio telescopes can pick up radio waves and convert them to sounds but is that really what they are used for. I would assume radio telescopes are mostly used to pick up radio waves and convert them to images, like the ones seen on the world wide telescope. Am I right in this assumtion? Daren Campbell Tri-Co Realty & Investment Co. Ph. 801-571-8833 Fax 801-571-9888 -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of utah-astronomy-request@mailman.xmission.com Sent: Wednesday, June 11, 2008 10:13 AM To: utah-astronomy@mailman.xmission.com Subject: Utah-Astronomy Digest, Vol 64, Issue 18 Send Utah-Astronomy mailing list submissions to utah-astronomy@mailman.xmission.com To subscribe or unsubscribe via the World Wide Web, visit http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy or, via email, send a message with subject or body 'help' to utah-astronomy-request@mailman.xmission.com You can reach the person managing the list at utah-astronomy-owner@mailman.xmission.com When replying, please edit your Subject line so it is more specific than "Re: Contents of Utah-Astronomy digest..." Today's Topics: 1. Re: Saturday night at the Gravel Quarry (Joe Bauman) 2. Re: holograms (Richard Tenney) 3. Re: holograms (ROBERT MARILYN GRANT) 4. STS-ISS by Moon shortly (nothing political, Chuck <g>) (Canopus56) 5. Re: holograms (Joe Bauman) ---------------------------------------------------------------------- Message: 1 Date: Tue, 10 Jun 2008 19:21:44 -0700 (PDT) From: Joe Bauman <josephmbauman@yahoo.com> Subject: Re: [Utah-astronomy] Saturday night at the Gravel Quarry To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Message-ID: <402454.80204.qm@web38908.mail.mud.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 Oh, c'mon. As long as we keep it friendly, a little rough-housing over politics now and again is a good thing. -- jb Overall a worthwhile event for SLAS, great viewing if you hung around and a pretty good night for observing and NO POLITICS. (HINT!) Bob Taylor _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com ------------------------------ Message: 2 Date: Tue, 10 Jun 2008 19:42:27 -0700 (PDT) From: Richard Tenney <retenney@yahoo.com> Subject: Re: [Utah-astronomy] holograms To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Message-ID: <495102.34496.qm@web53211.mail.re2.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 I'm probably the least qualified to comment here (never had college physics, but I did dabble a little in holography in H.S.); I doubt you could create a hologram with filters, but I know you can see holograms using filters, FWIW. --- Joe Bauman <josephmbauman@yahoo.com> wrote:
I've been thinking about Chuck's question, basically what I meant by non-laser-produced holograms, and I admit it's hard to describe my idea. That's probably because it's a b.s. idea. But here goes: There are filters, I assume grid-like, that can eliminate most wavelengths of light. If you could put together one that eliminated all but one wavelength, would that one wavelength work like a laser for the purpose of creating a hologram? I think holograms are possible because the laser illuminating the target emits just one frequency of light. When that light hits the target and bounces back to the film, the waveforms from interfering light bouncing back from various objects are preserved on the film. When a laser shines on the developed film, those overlapping waveforms are reconstituted and you see the object that was photographed in 3D. The fact that the laser is an extremely powerful pulse of light has nothing to do with this process; it's the single-wavelength property that is important. My idea is, what if you were to place a piece of photographic film in a shallow box, with the filter in front of the film, in ordinary daylight. Would you get the same effect because only waveform was penetrating the filter? Of course, to actually see the hologram (assuming you really could make one that way), I assume you'd need to illuminate the film with a laser. Thanks, Joe
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------------------------------ Message: 3 Date: Tue, 10 Jun 2008 22:31:56 -0600 From: "ROBERT MARILYN GRANT" <cincoymaya@msn.com> Subject: Re: [Utah-astronomy] holograms To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Message-ID: <BAY106-DAV142A37CF682ECB9140EC4C0B20@phx.gbl> Content-Type: text/plain; charset="iso-8859-1" Joe- I claim no expertise about holograms, but I remember watching my college roommate (Physics Major) making some. As I recall, the two light waves must have both the same frequency AND the same wave phase (called "coherence") in order to cause an interference pattern than can be recorded on film. I don't know how you can get coherent light except from a laser, but maybe someone else can chime in. Due to the difficulty of getting two lasers into coherence, a single laser was used, with the light going thru a splitter to direct the light at the object in two different paths. When the two light paths recombined, the differences in path lengths caused localized out of phase interference, the pattern of which was recorded on film. This is my layman's perspective. Bob Grant ----- Original Message ----- From: Joe Bauman<mailto:josephmbauman@yahoo.com> To: Utah Astronomy<mailto:utah-astronomy@mailman.xmission.com> Sent: Tuesday, June 10, 2008 11:06 AM Subject: [Utah-astronomy] holograms I've been thinking about Chuck's question, basically what I meant by non-laser-produced holograms, and I admit it's hard to describe my idea. That's probably because it's a b.s. idea. But here goes: There are filters, I assume grid-like, that can eliminate most wavelengths of light. If you could put together one that eliminated all but one wavelength, would that one wavelength work like a laser for the purpose of creating a hologram? I think holograms are possible because the laser illuminating the target emits just one frequency of light. When that light hits the target and bounces back to the film, the waveforms from interfering light bouncing back from various objects are preserved on the film. When a laser shines on the developed film, those overlapping waveforms are reconstituted and you see the object that was photographed in 3D. The fact that the laser is an extremely powerful pulse of light has nothing to do with this process; it's the single-wavelength property that is important. My idea is, what if you were to place a piece of photographic film in a shallow box, with the filter in front of the film, in ordinary daylight. Would you get the same effect because only waveform was penetrating the filter? Of course, to actually see the hologram (assuming you really could make one that way), I assume you'd need to illuminate the film with a laser. Thanks, Joe _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com<mailto:Utah-Astronomy@mailman.xmission.c om> http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy<http://m ailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy> Visit the Photo Gallery: http://gallery.utahastronomy.com<http://gallery.utahastronomy.com/> Visit the Wiki: http://www.utahastronomy.com<http://www.utahastronomy.com/> ------------------------------ Message: 4 Date: Tue, 10 Jun 2008 22:25:45 -0700 (PDT) From: Canopus56 <canopus56@yahoo.com> Subject: [Utah-astronomy] STS-ISS by Moon shortly (nothing political, Chuck <g>) To: Utah Astronomy List Serv <utah-astronomy@mailman.xmission.com> Message-ID: <440909.44347.qm@web32603.mail.mud.yahoo.com> Content-Type: text/plain; charset=us-ascii Poor quality digicam capture of part of the overflight. Gives some sense of the relative angle movement of the ISS during overflight. About 6 feet of the roof line of the adjacent house gives some sense of scale. http://members.csolutions.net/fisherka/astronote/photos/20080609ISSOverpass. avi 5megs I misjudged the TFOV of the orbit path relative to the Moon. The ISS went underneath the camera frame. Then repositioned. Peace - Kurt ------------------------------ Message: 5 Date: Wed, 11 Jun 2008 09:12:38 -0700 (PDT) From: Joe Bauman <josephmbauman@yahoo.com> Subject: Re: [Utah-astronomy] holograms To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Message-ID: <563098.37399.qm@web38903.mail.mud.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 That's what I love about this newsgroup -- there's always somebody who knows enough about a subject to help me learn! Also I appreciate that I can venture a probably-dumb idea without somebody making fun of me. Thanks all, Joe ROBERT MARILYN GRANT <cincoymaya@msn.com> wrote: Joe- I claim no expertise about holograms, but I remember watching my college roommate (Physics Major) making some. As I recall, the two light waves must have both the same frequency AND the same wave phase (called "coherence") in order to cause an interference pattern than can be recorded on film. I don't know how you can get coherent light except from a laser, but maybe someone else can chime in. Due to the difficulty of getting two lasers into coherence, a single laser was used, with the light going thru a splitter to direct the light at the object in two different paths. When the two light paths recombined, the differences in path lengths caused localized out of phase interference, the pattern of which was recorded on film. This is my layman's perspective. Bob Grant ----- Original Message ----- From: Joe Bauman To: Utah Astronomy Sent: Tuesday, June 10, 2008 11:06 AM Subject: [Utah-astronomy] holograms I've been thinking about Chuck's question, basically what I meant by non-laser-produced holograms, and I admit it's hard to describe my idea. That's probably because it's a b.s. idea. But here goes: There are filters, I assume grid-like, that can eliminate most wavelengths of light. If you could put together one that eliminated all but one wavelength, would that one wavelength work like a laser for the purpose of creating a hologram? I think holograms are possible because the laser illuminating the target emits just one frequency of light. When that light hits the target and bounces back to the film, the waveforms from interfering light bouncing back from various objects are preserved on the film. When a laser shines on the developed film, those overlapping waveforms are reconstituted and you see the object that was photographed in 3D. The fact that the laser is an extremely powerful pulse of light has nothing to do with this process; it's the single-wavelength property that is important. My idea is, what if you were to place a piece of photographic film in a shallow box, with the filter in front of the film, in ordinary daylight. Would you get the same effect because only waveform was penetrating the filter? Of course, to actually see the hologram (assuming you really could make one that way), I assume you'd need to illuminate the film with a laser. Thanks, Joe _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com ------------------------------ _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com End of Utah-Astronomy Digest, Vol 64, Issue 18 **********************************************
I really liked Contact but I fear the scene of Ms. Foster listening gave a lot of people the wrong impression. Radio telescopes like the refractors and reflectors we use all pick up basically the same thing, namely electromagnetic radiation. The difference being the wavelength of that radiation. Ours pick up the part of the spectrum we can see (visible light) and record with film/ CCDs and then display on a monitor or as a print while radio telescopes pick up parts of the spectrum we can not see but which can still be recorded and displayed on a monitor or as a print. So yes, your assumption is correct. BTW, in either case it is possible to turn the data into sound but other than for fun or for movies it's really not necessary. patrick On 11 Jun 2008, at 10:53, Daren Campbell wrote:
I'm new to the world of astronomy and while studying the different forms of electromagnetic radiation (light) I've had a question in my mind that I know is a stupid question but I can't help but ask.... Why is radio astronomy associated with listening? Or is it? All I have ever learned about science comes from the movies and I remember watching "Contact" with Jodi Foster's character sitting with her eyes closed "listening to the stars". I suppose radio telescopes can pick up radio waves and convert them to sounds but is that really what they are used for. I would assume radio telescopes are mostly used to pick up radio waves and convert them to images, like the ones seen on the world wide telescope. Am I right in this assumtion?
Daren, Funny this would come up right now. I just read an article in July's Reader's Digest about a young female radio astronomy PhD student who moonlights as an amateur roller derby athlete (if that's the correct term). She specifically mentioned the same scene with Jodie Foster in Contact and called it "crap" (a direct quote). Most meaningful data from radio receivers for astronomical purposes come in the form of graphs and numbers, not sounds or images. As Patrick mentioned, the data can be transformed into sound and even pretty pictures using false-color techniques, but the altered data are then strictly cosmetic, so to speak. The very short range of visible EM data that humans can sense directly (the visible spectrum, and some UV radiation that we ultimately sense as a sunburn) shows only a tiny percentage of the total volume of EM data from which we can learn about the universe. Unfortunately, the data that we collect from the EM spectrum that we cannot directly sense such as radio waves, infrared radiation, cosmic rays and so forth must be converted to some kind of output that we can sense in order to interpret the data. The most common output is visual, but I suppose that it would be possible to create tactile images of a galaxy, or the "taste" of a star. What we see in Contact is Hollywood's naïve and simplistic interpretation of something they do not understand and didn't take the time to do so. Hollywood's rationale: Radio = sound broadcasts, so radio astronomy must also equal some kind of sound output. I hesitate to single out anyone, but one active participant in SLAS's public star parties often brings a radio receiver that is tuned to some cosmic wavelength (I don't recall which). The output that he has chosen is a circular array of flashing LED's - interesting to look at, but in my opinion, provides no meaningful information, especially for our general public who probably haven't a clue as to what is going on. I didn't mean to carry on. So much for my $0.92. Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, June 11, 2008 10:45 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Radio Astronomy Question I really liked Contact but I fear the scene of Ms. Foster listening gave a lot of people the wrong impression. Radio telescopes like the refractors and reflectors we use all pick up basically the same thing, namely electromagnetic radiation. The difference being the wavelength of that radiation. Ours pick up the part of the spectrum we can see (visible light) and record with film/ CCDs and then display on a monitor or as a print while radio telescopes pick up parts of the spectrum we can not see but which can still be recorded and displayed on a monitor or as a print. So yes, your assumption is correct. BTW, in either case it is possible to turn the data into sound but other than for fun or for movies it's really not necessary. patrick On 11 Jun 2008, at 10:53, Daren Campbell wrote:
I'm new to the world of astronomy and while studying the different forms of electromagnetic radiation (light) I've had a question in my mind that I know is a stupid question but I can't help but ask.... Why is radio astronomy associated with listening? Or is it? All I have ever learned about science comes from the movies and I remember watching "Contact" with Jodi Foster's character sitting with her eyes closed "listening to the stars". I suppose radio telescopes can pick up radio waves and convert them to sounds but is that really what they are used for. I would assume radio telescopes are mostly used to pick up radio waves and convert them to images, like the ones seen on the world wide telescope. Am I right in this assumtion?
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.2.0/1497 - Release Date: 6/11/2008 8:32 AM No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.3.0/1499 - Release Date: 6/12/2008 7:13 AM
Kim: I wouldn't be too harsh on the creators of "Contact". They did after all hire Carl Sagan to help them get the science at least close to right, though I doubt Carl had final review on screenplay. You will find pockets of ignorance all over the place in movies and television. Recently an episode of Nova had Issac Newton peering at the sky through the wrong end of his telescope. This was followed by a special on John Dobson where John freely admits that he has never taken a course in astronomy, yet he feels free to rail against physicts who actually know something about the science. I have the greatest respect for John as a teacher of telesope makers and as a science popularizer but as a cosmologist he does more harm than good. The first problem, as I see it, is that the liberal arts college graduates have been carefully cleansed of any knowledge about science, and the scientific method. The people who run the media do not know how little they know about science. They also assume that their level of knowledge is adequate for the rest of us. The second problem, as I see it, is that science is too large for any one man to keep up with and even the giants of science waste their time in dead ends. Kepler tried to force the solar system into his ideas on number sequences. He was wrong. Newton abandoned astronomy and went off into decades of mysticism. He was wrong. Fred Hoyle, after doing pioneer work in nucleosynthesis lost his way with steady state cosmology. He was wrong. It's no supprise then that the average amateur is looking around for transporter beems and trilithium crystals after decades of watching Star Trek. And John Dobson can be excused for his views on cosmology, even though he is dead wrong. We make progress, on funeral at a time. DT __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Thanks for your insightful comments, Daniel. I tend to be a bit "anal" (ala Freud) when it comes to details, so I do get annoyed with Hollywood when they screw them up. Forgive me if I rail too much. Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of daniel turner Sent: Thursday, June 12, 2008 2:33 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Radio Astronomy Question Kim: I wouldn't be too harsh on the creators of "Contact". They did after all hire Carl Sagan to help them get the science at least close to right, though I doubt Carl had final review on screenplay. You will find pockets of ignorance all over the place in movies and television. Recently an episode of Nova had Issac Newton peering at the sky through the wrong end of his telescope. This was followed by a special on John Dobson where John freely admits that he has never taken a course in astronomy, yet he feels free to rail against physicts who actually know something about the science. I have the greatest respect for John as a teacher of telesope makers and as a science popularizer but as a cosmologist he does more harm than good. The first problem, as I see it, is that the liberal arts college graduates have been carefully cleansed of any knowledge about science, and the scientific method. The people who run the media do not know how little they know about science. They also assume that their level of knowledge is adequate for the rest of us. The second problem, as I see it, is that science is too large for any one man to keep up with and even the giants of science waste their time in dead ends. Kepler tried to force the solar system into his ideas on number sequences. He was wrong. Newton abandoned astronomy and went off into decades of mysticism. He was wrong. Fred Hoyle, after doing pioneer work in nucleosynthesis lost his way with steady state cosmology. He was wrong. It's no supprise then that the average amateur is looking around for transporter beems and trilithium crystals after decades of watching Star Trek. And John Dobson can be excused for his views on cosmology, even though he is dead wrong. We make progress, on funeral at a time. DT __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.3.0/1499 - Release Date: 6/12/2008 7:13 AM No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.3.0/1499 - Release Date: 6/12/2008 7:13 AM
participants (4)
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daniel turner -
Daren Campbell -
Kim -
Patrick Wiggins