What is Telescope: Definition and 513 Discussions

A telescope is an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects, or various devices used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. The first known practical telescopes were refracting telescopes invented in the Netherlands at the beginning of the 17th century, by using glass lenses. They were used for both terrestrial applications and astronomy.
The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. The word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.

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  1. Y

    Stargazing Which telescope is best for amateur stargazing?

    This question may have been there on PF, but I didn't find it. I am already in love with physics and find looking at the cosmos quite inspirational(like something which gives you chills). I was thinking of buying a little telescope. I eventually found a DIY kit called the...
  2. Greg Bernhardt

    Stargazing The What telescope are you using thread

    The "What telescope are you using" thread What telescope and other equipment are you currently using?
  3. enorbet

    Stargazing Telescope that can easily be connected to a laptop

    Greetings! I have read every post in this thread and I'm suitably impressed with the variety and quality of posters so I think I may get a good answer here. Although I have only minimal to moderate knowledge of where things are in the sky, I do see the value in Dobson's and respect the...
  4. PhysicoRaj

    Stargazing Celestron Powerseeker 60AZ Telescope

    Hi, After all these years of naked eye observations, I finally decided to get a telescope. So, I chose this: Celestron Powerseeker 60AZ Telescope...
  5. R

    Stargazing Telescope to see up close to nebulas and galaxies

    Hello all, i am beginner in astronomy and want to buy a telescope (which will be my first) but don't know much about it. i am seeking for telescope to see up to nebulas and galaxy, i found some telescope on one online site, they are-...
  6. G

    Stargazing Is a Geo Stationary Satellite the Key to Building the World's Biggest Telescope?

    sir i am taking part in the google science fair with my own design of worlds biggest telescope. my design is given below:- we will have a geo stationary satellite, which will revolute around the Earth and we will have a big mirror on the Earth with focus on the satellite when rays will come...
  7. C

    Stargazing How big would a neutrino telescope have to be?

    Greetings, The IceCube neutrino detector array in the antartic is a cubic kilometer and has deceted about 28 neutrinos from outside the solar system. So the resolution is almost nothing. I am wondering how large a detector array would have to be to serve as a telescope to observe what I am...
  8. S

    Help with Telescoping Series Problem

    Homework Statement Problem is attached in this post.Homework Equations Problem is attached in this post. The Attempt at a Solution Attempt at solution is attached. Apparently the answer is -pi/6, however I've solved for it several times and keep getting my answer as pi/3 via Telescoping Series
  9. R

    Stargazing ALMA vs James Webb: Which telescope will reveal more about the universe?

    What are the differences between these telescopes and which telescope will do more for our understanding of the universe? I know that ALMA is a series (66) radio telescopes, however, it also operates with optical telescopes. James Webb is an infrared telescope.
  10. shanepitts

    Stargazing City viewing with dobsonian telescope?

    My father will be lending me his dobsonian telescope, but I live in the city. Is there much to see through all this light pollution?
  11. T

    Stargazing Best Telescope for under 1400$.

    Due to my interest in astrophysics, I have decided to consider purchasing a telescope. I am looking for something under 1.4k that would allow viewing of Jupiter, the moon, Saturn, venus transit, and deep space objects such as the Orion Nebula, Crab Nebula and possibly M-27, M-51, Triangulum...
  12. S

    Stargazing Single-dish radio telescope aperture

    hello everyone! this is a new single-dish radio telescope, FAST, under construction: http://nextbigfuture.com/2011/06/chinas-five-hundred-meter-aperture.html The aperture is 500 m. But the illuminated aperture is only 300m. So what is the advantage of bigger aperture? is the angular...
  13. C

    Solving Telescope Optics Homework Question Involving Five Lenses

    Homework Statement *The diagram of the telescope is attached* Question states A telescope is constructed from five thin lenses of Diameter D and focal lengths 2F, F, F,F,2F located at x = 0,2F,4F,6F,8F Trace the path of a ray entering the system parallel to the optical axis The...
  14. F

    Stargazing I got a telescope what to see?

    I got the celestron firstscope what to see now?
  15. B

    Finding angular velocity of telescopic arm

    Homework Statement So ,here is the question : The structure is shown in the picture. All I need is to find the angular velocity of telescopic arm BC ,in this current position. http://img197.imageshack.us/img197/3954/w6e.JPG Homework Equations Well,them simple ω=rXv/r\bulletr...
  16. H

    Stargazing Will the James Webb telescope see past the big bang?

    Will the James Webb telescope be able to see beyond the Big Bang in principal? I realize, in reality this is not possible, but I'm curious if it will see as far back as possible, or if the telescope has limits, and eventually we will need a better telescope to truly look deep. Thanks!
  17. H

    Stargazing How deep can Hubble Telescope see?

    How deep can Hubble Telescope see?? -I understand that the Hubble telescope can only resolve galaxies at about 13 billion years old, using gravitational lensing. I am curious, is this because the telescope does not have the power to see farther? Or is this because there are no farther...
  18. I

    Powerful Telescope Needed to See Moon's Roadway?

    Hi all, Yet another question (all coming up due to re-examining my novels for rewriting): Regarding telescopes, how powerful would a telescope have to be to make out a two lane road / highway on our moon, and when (in Earth history) did someone build such a telescope? I'm not looking...
  19. R

    Stargazing What kind of telescope is this

    I have a scope that I'm trying to find some info on. It's a solid brass scope with a solid brass tripod. I can't find ANY markings, letters, numbers etc. anywhere...at all.
  20. jijopaul

    Stargazing Can a Simple 80x Telescope Reach Maximum Resolution?

    what will be the configurations for a simple 80x telescope? i need to optimize it to the maximum resolution.
  21. S

    Stargazing Saving the telescope with damaged optics

    I have a Celestron NexStar 4SE, I damaged the optics. Is there a company who just sells the telescope without the computerized mount?
  22. S

    Why the discrepancy between telescopes and big bang?

    I am wondering why it is that we can look into Hubble's Deep Field and see galaxies 13.7 billion light years away, and 13.7 billion years ago, yet Big Bang theory tells us that 13.7 billion years ago all matter in the universe was very close together. Shouldn't we be seeing in HST that the...
  23. C

    Partial Sum Formula of Telescoping Series: 1/2*(1+1/2-1/(n+1)-1/(n+2))

    Homework Statement Find the formula of the partial sum of the series Ʃ1/[k(k+2)] k from 1 to infinity Homework Equations The Attempt at a Solution Using partial fractions i rewrite the series as 1/2*Ʃ[1/k] - [1/(k+2)] Then I start writing out the series from k=1 to 5...
  24. siddharth23

    Stargazing How far can the best telescope see?

    Using the best technology available, how far can you see things clearly? As in how many light years?
  25. S

    Stargazing B mode detected by South Pole Telescope

    http://arxiv.org/abs/1307.5830 but its from gravitational lensing not primordial gravity waves so guess we are still waiting for those, but a good sign methinks.
  26. jim hardy

    Stargazing Helping my school with a telescope, advice appreciated

    My local high school has a telescope that has sat unused for at least a decade. I play poker with the principal and have an opportunity to assist getting it back into usability. Visited it this morning doesn't appear to need much it's a 12.5 inch Newtonian in about six foot tube on equatorial...
  27. Greg Bernhardt

    Stargazing Hubble telescope finds a planet where it rains glass

    http://www.cnn.com/2013/07/11/world/space-blue-planet/index.html?hpt=hp_t1
  28. mrspeedybob

    Stargazing Question about reflecting telescope design.

    Error in title. I meant refracting. At every transition between air and glass it seems to me like there would be some reflection. Each photon it seems would have a certain probability of entering a lens and reflecting off of both of the lenses interior surfaces and then continuing on into the...
  29. I

    Stargazing What Type of Telescope Should I Buy as a Beginner?

    Hello there, I'm new around here. :) I'm looking to get my first ever telescope and so I wanted a bit of advice on what would be the best telescope to fit my needs and also if you could remember, please mention what type of telescope you first purchased! As a beginner, I'm looking to view...
  30. fsonnichsen

    Stargazing FOV for galilean vs keplerian telescope

    It is my understanding that a Galilean telescope has a smaller field of view (FOV) than a Keplerian. Doing some "pencil" ray tracing on a sheet of paper I don't seem to get this result. Can anyone suggest a source that works the math for the FOV of both types? thanks Fritz
  31. mishima

    Stargazing White paint of radio telescopes

    I was wondering what kind of paint is used for radio telescopes, generally. In the case of the Green Bank Telescope, the idea is to get white at visible wavelengths, black at mid-infrared, and transparent at radio wavelengths. Titanium dioxide based paint was one substance cited on the...
  32. T

    Stargazing Is it worth getting a telescope?

    I've heard countless stories from my friends saying they only used theirs once or twice before it got old. I've been really interested in astronomy but is it worth the money?
  33. E

    High energy neutrino telescopes

    Hello, I am opening this thread so as to discuss if possible what you believe is the science case of building a neutrino telescope. Being a fanatic in the field , I would like to hear opinions from whoever wants to say about whether it is important to build such a detector and why. Thank you!
  34. K

    Ray diagrams for an astronomical telescope

    Homework Statement An astronomical telescope is constructed using 2 convex lenses. The objective lens is of focal length 40cm and eyepiece lens is of focal length 10cm. Let d be the distance between the 2 lenses. Draw ray diagrams for the following situations. 1.When d=50cm 2.When d>50cm...
  35. G

    Stargazing Using the Celestron C90 telescope

    Hi, I have a few questions about telescopes; (But a quick disclaimer: I know almost nothing about telescopes or astronomy) My uncle lent me his Celestron C90 telescope (he said it would be a good thing to start with) and I tried it out just now. I saw the moon with it, and it was incredible...
  36. N

    Stargazing Pictures from the Hubble Space Telescope

    78 Pictures from the Hubble Space Telescope http://www.space.com/15235-hubble-space-telescope-latest-photos.html
  37. Greg Bernhardt

    Stargazing $1.3 billion Thirty Meter Telescope (TMT) gets approved

    http://news.sciencemag.org/scienceinsider/2013/03/thirty-meter-telescope-gets-smal.html
  38. T

    Archived Reflecting telescope calculation

    Homework Statement A reflecting telescope has a radius of curvature of 3.0m for its objective mirror and a radius of curvature of -1.50m for its eyepiece mirror. If the distance between the two mirrors is 0.90m, how far in front of the eyepiece should you place the photographic film to record...
  39. B

    Telescoping Series involving 3 parts.

    Homework Statement Determine whether the series is convergent or divergent by expressing s sub n as a telescoping series. If convergent find the sum. \sum_{n=2}^\infty \frac{1}{n^3-1} The Attempt at a Solution First thing I did was partial fraction decomposition. Resulting in: Ʃ (n=2 to ∞)...
  40. B

    Telescope Lenses: Focal Lengths 20cm/1cm/100cm/5cm/10cm/2cm/25cm/75cm

    Which two of the following lenses could be used to construct a telescope? Focal lengths: 20cm/1cm/100cm/5cm/10cm/2cm/25cm/75cm (a.) That magnifies 20x and has a length of approx 1.0m (b.) magnifies by 15x (c.) magnifies 50 x I used magnification=telescope focal length/eye piece...
  41. P

    Very small holographic laser projectors and diffraction.

    In thinking about what it would take to make a feasible invisibility cloak or holographic disguise or perfect hologram room, I've imagined something that works like this: A light beam "image" is projected onto a device designed to refract or reflect it in all directions, but only 1 color in any...
  42. D

    How Do You Calculate the Focal Length of a Telescope's Objective?

    Homework Statement An optical telescope with a 12mm eyepiece makes the Moon appear to have an angular diameter of 30 degrees. What is the focal length of the telescope's objective? Homework Equations magnification=focal length of objective/focal length of eyepiece The Attempt at a...
  43. D

    Why Does the Observed Frequency Increase When a Galaxy Approaches?

    Homework Statement Atomic hydrogen emits a characteristic spectral line with a frequency of 1421 MHz. A radio telescope observes this line in a certain galaxy at a frequency of 1432 MHz. Is the galaxy approaching or receding, and at what speed (in km/s)? Homework Equations The Attempt at...
  44. J

    The masking effect of the sky scattering of visible light

    It is very well known that the sky scattering of visible light decrease with the wavelength, it is bigger in the blue portion of the spectrum( the reason why the sky is blue ) and is lower on the red portion of the spectrum, this scattering is even lower on the infrared section and lower still...
  45. M

    Which "category" of space career should i go into?

    I have always loved space and the universe. I think that as a civilization we need to dedicate more time, funds, and efforts to exploring and studying the things beyond our own Earth. A freshman in college, I need to soon settle on a major that I want to aim for (Bachelor's degree). Let me make...
  46. D.R.U

    Stargazing Mirror Mounting Structure in Space Telescope

    Hello/... Give me reference or ready made material ...for following mounting method of mirror in space telescope and its mechanical Design and structure for mounting mirror.
  47. H

    Stargazing UY Scuti, the biggest known star, viewed through a telescope

    I have been appointed the project manager at Rutherfurd Observatory, and was thus granted access to use the primary telescope. I spent 2 days trying to locate UY Scuti and finally, I've did it! For those who don't know what UY Scuti, it's the biggest known star in the universe. If it were to be...
  48. B

    As a Physics Phd student, what are the skill required for Quant?

    First of all I read a lot info from post by twofish-quant but I am not sure if its outdated already. So I am currently in the second year of my grad school (PhD program) in physics, specialized in observation cosmology (galaxy survey aiming at Dark Energy/inflation/BAO/...). As much as I like...
  49. B

    What are the skills required to become a Quant as physics PhD?

    First of all I read a lot info from post by twofish-quant but I am not sure if its outdated already. So I am currently in the second year of my grad school (PhD program) in physics, specialized in observation cosmology (galaxy survey aiming at Dark Energy/inflation/BAO/...). As much as I like...
  50. N

    Stargazing Buying a Telescope: First-Time Advice

    I have made up my mind about buying a telescope. The one i will be buying is: http://shop.seben.com/sms/shop/index.php?p=b3JnYT1zZWJlbiZncm91cD0zJmxhbmc9MiZjdXJyPTE=&action=products&cat=1&mode=view&id=1 But i do still have some questions. This is my first telescope, will it be easy for a new...
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