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. Clear Mind

    Stargazing Does a Radio Telescope Have Aberration and How Does it Affect Its Performance?

    I was studyng my exam of astrophysics laboratory, while treathing the optical aberration I've wondered: does radio telescope have aberration? Is a paraboloid antenna in a single dish affected by coma? and the radio telescope made by arrays of resonant structures? Maybe those are silly...
  2. P

    I Minimizing diffraction in images using a photodetector

    If I understand the phenomenon correctly; whenever we capture an image using a telescope, because the light that's emitted from a distance object acts like a wave, we notice a diffraction pattern in our image. Now, in the double slit experiment (I didn't create the image, excuse the "slot"...
  3. Duo Tao

    Stargazing Where to buy telescope that measures spectrum?

    Hi, I am going into the field of astrophysics and I am going to make my career a hobby, too. I want to buy a telescope that can measure the spectrum with CCD (astronomical spectroscopy) in a range of several hundreds of light years (like the Big Dipper). Does anyone know where can I get it...
  4. Decimal

    Can the Hubble telescope measure the diameter of Betelgeuse?

    Homework Statement The star Betelgeuse is 427 lightyears from earth. Betelgeuse has a diameter 800 times that of the sun, where the diameter of the sun equals ##1.39*10^6 km##. Given that Betelgeuse has an angular resolution given by the Rayleigh Criterion of 58 nRad, is it possible for the...
  5. Hawksteinman

    Stargazing Is the INTEY Ultra-Clear Telescope a Good Choice for Beginner Astronomers?

    I just bought this it will be my first telescope. I won't post the link to the website but I'll post the name and description of the telescope :) INTEY Ultra-Clear Telescope Christmas Gift Portable Astronomy Telescope Entry-level Telescope for Astronomers and Children (with an Additional...
  6. D

    Stargazing Programable telescope that will point to any spot on Earth?

    Is there a programmable telescope that will point to any spot on Earth from my location that I could simply plug in the latitude and longitude and it would point at the location anywhere on Earth. For instance, if I wanted it to point at the LHC (Large Hadron Collider), could I just plug in the...
  7. ecjoyner

    Calculating and Customizing Telescope Dew Heater Bands for Optimal Performance

    I want to make my own scope dew heaters, I have 8 meters of nichrome band, with 1,82 ohm/meter resistance. How do I calculate the length for a specific temperature (around 8 Celsius over ambient) and how to wrap it i.e. in a coil or in a series of parallel 320° circles? The circumference of the...
  8. S

    Stargazing How hard is it to find filtered color bands using telescope?

    I am currently working on writing an ML program that predicts star formation rate of a galaxy given the magnitude of filtered color bands (ugriz). I have a simulated data which contains these info to train on but if I want to use this on an observable galaxy, I'd need to physically obtain the...
  9. S

    Stargazing Impact of Kepler Telescope Findings on the Drake Equation

    How much more refined are the various variables of the Drake Equation in view of the recent findings by the Kepler Telescope? I imagine fp and ne would surely be better estimates. Is there a study on this anywhere?
  10. A

    B Telescope and Stopwatch for the Mass of a Planet

    I was wondering if it is possible to use only a stopwatch and a telescope to find the mass of a planet, such as Saturn. I've experimented with a couple of things but I keep running into problems. I previously asked this question in the homework section, but it does not involve numbers, is not...
  11. sophiecentaur

    Stargazing Telescope Guiding Techniques: Improving Exposure Times through Auto Guiding

    My star pictures are improving and I am at the next stage of needing some money. My tracking seems to be limiting my exposure times to only a couple of minutes and there is a hint of star trails. So I need to do some auto guiding. I have been doing some homework. In the systems I have seen...
  12. NFuller

    Insights Getting Started with Solar System Imaging - Comments

    Greg Bernhardt submitted a new PF Insights post Getting Started with Solar System Imaging Continue reading the Original PF Insights Post.
  13. F

    B Telescope with a pinhole as the Objective?

    Will a telescope work if its front lens (Objective lens) is replaced with a pinhole ? What if both lenses ( Objective and eyepiece) are replaced with pin holes ?
  14. C

    Stargazing Looking for a beginner's telescope....

    Hi there, I love physics and I'd like to begin a bit of astronomy. I want to invest in a beginners telescope but I haven't a clue about what to buy. Some that I'm looking at are linked here: https://www.amazon.com/dp/B00XQMLA7Q/?tag=pfamazon01-20...
  15. D

    Coupling two mechanical pieces for a telescope mount

    Hello PF community! Quick introduction: I'm a fresh-out-university mechanical engineer working on a telescope altitude-azimuth mount hobby project. The mount will be designed using rotary platforms (powered by internal motors) to move the mount structure in the altitude and azimuth directions...
  16. bruha

    Stargazing Stunning Telescope Photo of Vega Captured with 130mm Eyepiece - See the Beauty!

    Hello, I made some photos of Vega..just by mobile camera through telescope 130 mm eyepiece 12,5 mm. Fig. "vega_cam" is made by usb camera eyepiece adapter but I did not manage to focus it properly..
  17. lomidrevo

    Stargazing Worth it to buy 2" eyepieces for Newtonian telescope?

    Greetings to all stargazers! I am a happy owner of a Newtonian telescope 200/1200 on Dobson mount, more detailed specifications on this link (http://skywatcher.com/product/dob-8-traditional/). It has a 2” focuser with a 1.25” adapter. So far, I was using only the two included eyepieces, 1.25”...
  18. T

    I Quantum entangled image sensor for space camera-telescope

    Could this be a possibility at some point? Since entanglement is not affected by distance, could we send cameras out to extremely distant places and get instantaneous signals? Only the image sensor would have to be entangled. It would still take the same amount of time as usual to get the camera...
  19. bruha

    Stargazing Vega & Arcturus: Amazing Telescope Photos

    Hello, I just try to make photo (quite amateur) of Vega and Arcturus (by 76 mm scope Newtonian) If you like watch it ...
  20. N

    A Quantum telescope (different meaning)

    Hello, term quantum telescope is usually related to beating diffraction limit as described for example there. But my question is not related to it. Recently I have read paper about Counterfactual quantum communication. If this really works and someone is sending quantum engaged particles to our...
  21. Zoiona

    Stargazing What are some good beginner telescopes for under £100?

    Hello! I want to buy a telescope so I can get into astronomy but I have no idea what to look for. I done a bit of research but none of it has been very helpful :(. My budget is a maximum of £100. Does anyone know some good beginner telescopes I could get? I'm also interested in astro-photography...
  22. B

    Stargazing Considerations for size of telescope survey

    Hello, I am writing a (mock) proposal for gaining some observation time on a telescope. One part that I am having a hard time with is, what considerations are made when deciding how large a field to survey? Are astronomers primarily constrained by the amount of time they are likely to be...
  23. kolleamm

    Stargazing What's the Best Telescope for Astrophotography Under $1,500?

    I purchased a 6" mirror reflector telescope, but no matter how much I tried to get good photos all came out blurry, I'm guessing the mirror was low quality, also the tracking system made absolutely no sense and could not even find the Moon. Not just that but it wasn't stable either. So...
  24. L

    Stargazing Where is the Hubble Telescope?

    I've read that Hubble is in geosynchronous orbit, but precisely what point on Earth does it remain in orbit over?
  25. G

    Stargazing What telescopes are good for seeing planets and galaxies?

    Hello, I am currently considering on buying a telescope to do some of my own research and for sight seeing. Any recommendations? I would prefer to have a telescope that requires me to use code or at least a computer so I can familiarize myself with the mechanics.
  26. Cocoleia

    Magnification formula for a Galilean telescope

    Homework Statement I am asked to draw the ray diagram for an incident plane wave whose rays are at an angle α with respect to the optical axis of the telescope. I have done this, but I need to find an expression for the angle between the outgoing rays and the optical axis, in terms of f1, f2...
  27. P

    Stargazing How to build an optical telescope for research?

    So, my SPS group is building an optical and a radio telescope (using a typical TV dish). The trouble is, these are merely for showing kids and sometimes for us to just see the sky. Because of their small size, we won't be able to do a lot of research. What I need is a telescope like the...
  28. N

    Stargazing H.E.S.S. gamma ray telescope got an image of the moon

    https://en.m.wikipedia.org/wiki/File:Moon_egret.jpg Can we use better telescopes of this type (ground based gamma rays telescopes) to image the surface and subsurface of a planet with a lot of resolution?
  29. P

    Other Will building a telescope help my resume?

    The Physics group at my university is building an optical telescope (it will have a dome the size of an 8mX4m room and the mirror will have a diameter of about 65cm.) and we might also build a radio telescope or an array of telescopes which will work as one giant telescope. Also, I heard that we...
  30. TheCapacitor

    Optical DIY Telescope theory and questions

    I'm confused about the theory of the telescope I am making. My questions are: 1. Magnification - according to my image we should see magnification because the image we see is the image formed by the continuation of the dotted lines. Is that true? 2. Why do we need lenses with different size? If...
  31. B

    Stargazing Kepler Telescope Views Single Point in Space 4.2ly Away

    Astronomers are viewing a single point in space (.1 arcseconds), using the Kepler space telescope but to view a planet 4.2 light years from the Earth that would require a planet with a diameter of more than ten times the diameter of our solar system.
  32. G

    Stargazing What telescope is best for a beginner on a budget?

    I happened to find this site looking for a telescope. I am a newbie to telescopes. I had a cheap department store telescope about 30 years ago.I am looking for a telescope I can connect to a PC and displays on the screen for the purpose of making it easier for me and my 6 and 7 year old...
  33. M

    Stargazing Telescope Design: Calculating Total Distance from Primary Mirror to Eyepiece

    I am currently in the middle of constructing a Newtonian reflecting telescope and I had a question. The focal length for my primary mirror is 1500mm and 3mm for my eyepiece. My question relates to the path of the light inside the tube of a telescope. I understand that in a Newtonian reflector...
  34. jamalkoiyess

    Stargazing Radio Telescope Building Guide for Beginners

    Hello PF, I was wondering if there is any good guide to build a radio telescope that can give me an image not just a graph. I am just a starter so any advice or tips are relly appreciated.
  35. K

    A Can an event horizon telescope observe quantum gravity effects

    its commonly stated that no particle accelerator will ever be built that can probe the Planck scale. what about an can an event horizon telescope observe quantum gravity effects near a black hole, such as Sagittarius A* do the various candidates of QG such as string theory LQG asf gravity...
  36. C

    Stargazing Want to purchase new telescope

    Hello all, First of all thanks for taking the time to look at my post, and thanks ahead of time to those willing to answer my question. I've always loved Astronomy and have done quite a bit of self-study over the years. I have a pair of binoculars but want to get a telescope. I'll start by...
  37. russ_watters

    Stargazing Telescope or Binoculars for First Astronomy Device?

    A recent short-lived member got me thinking about the issue of telescope vs binoculars for a first stargazing device again after a few years of the issue sitting dormant. I hadn't participated in the particular necroresurrected thread, so it didn't have my take on the issue. Here it is: It...
  38. T

    Stargazing New Radio Telescope is World's Largest

    World's largest radiotelescope just completed. http://news.xinhuanet.com/english/2016-07/03/c_135485643.htm
  39. 0

    I Delayed choice quantum eraser scanning telescope

    Hi! :) I have this question regarding delayed choice quantum eraser - If my understanding is correct then interference pattern will form/not form based on whether there is erasing mirror in path of entangled particle - regardless of time when particle arrive at mirror. Should not it be...
  40. James Webb Space Telescope Instrument Installation

    James Webb Space Telescope Instrument Installation

    Time-lapse video of two dozen engineers and technicians successfully installing the package of science instruments of the James Webb Space Telescope into the telescope structure.
    • Hoophy
    • Media item
    • astronomy james webb space exploration spacecraft telescope
    • Comments: 2
    • Category: Astronomy and Cosmology
  41. S

    Stargazing Can you me with this Hershel telescope beam?

    I came to know that the PACS instrument of HERSHEL has a resolution of 5" at a scan speed of 20''/sec whereas it's 10'' at 60''/sec. The resolution has almost doubled with the scan speed. Can you please tell me why it's so?
  42. G

    Stargazing Can't see through my Telescope

    I bough a Newtonian reflector a while back, after it was assembled I couldn't see anything through the eyepiece. The viewfinder works perfectly fine, but when I look through the eyepiece it is just pitch black. Any suggestions?
  43. Erenjaeger

    Maximizing Telescope Sensitivity: The Importance of Mirror Size

    A telescopes sensitivity, or how much detail it can see is directly related to the size of the mirror area that collects light from the objects being observed. So a bigger mirror means higher resolution so you can see more detail at greater distances right? does it also mean it can collect more...
  44. O

    Stargazing The terrible distortions of the Hubble Telescope

    I'm not talking about the well known, miss-grinding of the main mirror which was corrected long ago . This picture illustrates well , my beef with the current images ... Every image of every star has four streaks of light , this is not so noticeable in pictures of galaxies where the stars...
  45. K

    How can I create an adjustable liquid lens system for windows?

    Hi everyone, I am working on a project on my final project in Product design. The project is about translating digital concept into the analogue world. In my project I am especially interested in the digital “Windows” and am trying to apply the functions and possibilities of digital on to...
  46. F

    Calculating focal length from a number of focal ratios

    Homework Statement A telescope has a focal ratio of f/7.5. You wish to use it with a spectrometer that requires a f/10 beam as its input. Compute the focal length of a 50mm diameter lens that, when inserted into the beam 150mm in front of the unmodified focal plane, produces the required beam...
  47. K

    Optical Is my DIY refractor telescope out of focus with the eyepiece?

    So, I recently finished my refractor telescope. I have a objective lens of 80mm and focal length of 900mm, 70mm focuser, tube length is 99.8 cm. I have a 25mm and 9mm eyepiece. I have been testing it out during the day time, on objects I can easily spot. First I use no eyepiece to focus on an...
  48. T

    I Event Horizon of Telescope Through Earth: Does It Exist?

    Assume we drill a hole through the Earth - through the center towards the other side. Then we use a telescope, point it through the hole and observe stars on the other side of the earth. The telescope experiences a constant acceleration from Earth's gravitation. Accelerated movements have an...
  49. M

    Help with lenses for hand-made telescope

    I'm trying to make a handmade telescope, but I'm stuck with the lenses I bought 2 lenses. they are the same "convex from one side and concave from the other side" like glasses lenses. then I knew that I need a double convex for both the object lens and the eyepiece lens. so I decided to put the...
  50. M

    Stargazing Facing difficulties with radio telescope measurements

    Hi Me and a couple of class mates are working on our bachelor's project of which the mission is to measure the temperature of the sun using a parabolic antenna. We are having great troubles trying to come up with an equation relating the antenna temperature (which we are able to calculate with...
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