What is Telescope: Definition and 515 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.

View More On Wikipedia.org
Recent contents Top users
  1. 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    First of all I read a lot info from post by twofish-quant but I am not sure if its outdated already.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...
  2. 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...
  3. PeterDonis

    The Block Universe: Examining the Rietdijk-Putnam Argument

    [Reposted from my PF blog] The "block universe" interpretation of SR has come up repeatedly in threads here on PF. Rather than link to them, I want to summarize the key argument that is made for the "block universe" being necessary, and then summarize the arguments I made in those threads to...
  4. V

    Locate Radio Sources Using Radio Microscope-1 Mhz

    Suppose there is a set of twenty tiny radio sources that are distributed randomly in an area of 1 mm2. What is the best way to locate each of these sources - as in identify them and their locations? We can suppose that all of them are of the same frequency of 1 Mhz. Thus if the radio telescope...
  5. Wes Tausend

    Solving the "Moon Big Ben" Dilemma - Gravities vs Time

    ... The other night my telescope buddy and I were discussing gravities vs time over a campfire and beverages. I mentioned that a clock on the moon should run faster than an identical clock on Earth because the gravity is weaker there. As an example, if we synchronized another rather large...
  6. K

    Day in the life of an astrophycisist?

    Hi. I'm at a very critical point in my life / education. In 3 months I have to apply to the university I will attend next summer. I'm torn between studying physics or biology - I have had biology for 6 months, physics only for 1 week in my whole life. But I've been interested in astronomy since...
  7. P

    Stargazing Is a Telescope Worth Buying for Limited Sky Visibility?

    I'm unable to see any stars or anything in general besides the moon when looking at the sky. This might be due to the light pollution as the actual pollution levels is very low. Is it worth buying a telescope here? Will I even be able to see anything in the sky like Mars or anything similiar...
  8. marcus

    BH can't evaporate in real surroundings (George Ellis)

    Common sense really. Space is full of CBR (not to mention other radiation and matter). They keep being fed. The surrounding CBR is warmer than the Hawking temperature of the hole and in effect blocks the Hawking radiation process. Ellis et al even calculate far into the future when the CBR is...
  9. S

    Looking for information about cryogenics

    Hello everybody. I'm Mike(Subchillin), I'm very new here and terrebly interested in ALL things Cryo. And I'd like to start by expressing gratitude to the creators of this amazing forum and all the active members, because simply knowing that there is an active online community of people who love...
  10. D

    How do we know the orbits of the planets?

    What exactly does it take to figure out the orbital parameters or planets and what's the Math behind it? Can it be done using only a telescope or is it necessary to send a probe?
  11. chasrob

    Most total e-folds from inflation

    I'm asking this just out of curiosity on my part.<grin> When I first heard of cosmic inflation, a long time ago, I went to the local university library to look at papers that made estimates of the total number of e-folds from various models. I'm not an expert in any area of science but I found...
  12. Dei

    Questions About Becoming an Astrophysicist or Astronomer

    Hi, I am a recent high school graduate, and my whole life I have been interested in astronomy. I have always stared in marvel at the night skies and read various books about constellations, etc. When my parents bought a telescope, that only spiked my interest further! I have, also, gained an...
  13. B

    Stargazing Cleaning a Telescope's Mirror: Tips and Techniques

    Hello, I have access to a pretty big telescope, at least when compared to others I've played with. I'm itching to set it up but the mirror is not in great shape. It has been in storage for a long time and there looks to be some corrosion. I was wondering if there is anything I need to be...
  14. Greg Bernhardt

    What is a Parabola? A 5 Minute Introduction

    Continue reading...
  15. Greg Bernhardt

    Understanding Conic Sections: Exploring the Plane-Cone Intersection

    Definition/Summary A conic section (or conic) is any curve which results from a plane slicing through an upright circular cone. If the slope of the plane is zero, it cuts only one half of the cone, and the conic is a circle (or a point, if the plane goes through the apex of the cone). If the...
  16. M

    Causailty and the speed of light

    Hi, I would be really grateful if someone could help me with two questions I have, both have puzzled me on and off for years. I have read what I can regarding these points, but a lot of it I don't understand (the maths specifically). I would love it is someone who understands this more than...
  17. mfb

    Name Exoplanets: IAU Plans to Name 305 Exoplanets

    The IAU plans to name 305 exoplanets. Currently, organizations can make suggestions, in 2015 the public can vote on those suggestions. This is organized on nameexoworlds.org (IAU press release) While a proper name is certainly nicer than "HD 121504 b", it won't be an easy task to keep up...
  18. G

    Could we read a newspaper from a satellite image?

    If the satellites are spread out as a big baseline telescope? Or there are other problems that even that method can't solve when watching the ground?
  19. anorlunda

    Does Aluminum Coating on Telescope Mirrors Turn into Aluminum Oxide?

    I saw on Nova thst large telescope mirrors have aluminum reflective coatings. Wouldn't that rapidly become an aluminum oxide costing? Are the coatings coated to keep oxygen out?
  20. B

    Angular Magnification of a telescope,

    Homework Statement A telescope consists of a mirror with radius of curvature 14.0 m and an eyepiece of focal length 19.0 cm. Approximately what is the value of its angular magnification I haven't yet been asked to find angular magnification given such little detail, my cyber-school program...
  21. S

    Radio Waves from Stars: Investigating the Mysteries

    dear sir i want to know what happens in certain stars that helps it give out radio wave we detect by radio telescope. can we compare with inductor in electronic circuit?
  22. davenn

    Vale Bill Bradfield - The loss of a comet hunter

    Bill was a fellow Australian and prolific comet hunter and discoverer Quoted from the Ice In Space site He will be truly missed in the astronomical community :( Regards Dave
  23. gfd43tg

    Triple redundancy sensor matlab code

    Homework Statement Hardware redundancy is important in many real-world engineering systems. Specifically, installing multiple sensors that measure the same quantity provides a level of safety in the event that one instrument fails during the mission lifetime. You do not want an expensive...
  24. marcus

    Radical new cosmic model (Barrau Linsefors one-up Penrose)

    ==from conclusions section on page 4 of Barrau Linsefors June paper== V. REBIRTH OF THE UNIVERSE AND TESTS OF THE MODEL In the far future, huge patches of our universe, with radii larger than the Hubble scale, will be completely empty. They will be pure dS spaces. If the model suggested in this...
  25. G

    Focal length eyepiece for telescope

    Homework Statement Suppose that you wish to construct a telescope that can resolve features 7.0 km across on the Moon, 384,000 km away. You have a 2.2 m-focal-length objective lens whose diameter is 10.5 cm. What focal-length eyepiece is needed if your eye can resolve objects 0.10 mm apart...
  26. G

    Maximizing Telescope Resolution: Finding the Optimal Eyepiece Focal Length

    Homework Statement Suppose that you wish to construct a telescope that can resolve features 7.0 km across on the Moon, 384,000 km away. You have a 2.2 m-focal-length objective lens whose diameter is 10.5 cm. What focal-length eyepiece is needed if your eye can resolve objects 0.10 mm apart...
  27. W

    Stargazing Quick and Easy Telescope Measurments?

    For my science fair, I need to take measurments (to scale) on a telescope, for example, I need to be able to point it towards the moon, and measure its radius. Now, my problem there is how will I measure this? Since my eye will be in the way, I can't use a ruler to find a crude measurement, so I...
  28. W

    Stargazing Choosing a Telescope: Orion vs Celestron

    Today I was bored, so I went into my closet and found an old telescope of mine. I spent like a half hour star-gazing, but quickly became bored. I couldn't see very far with this telescope, since it was a cheap one I got for Christmas a few years ago (and funny thing is, around the time I got it...
  29. I

    Interesting Telescope Image Recording and Transmission Design Problem Need help

    Homework Statement You have been tasked with the design of a new far-field, high resolution imaging system to be placed on the Hubble Space Telescope. This system will be used for taking deep space astronomical images with an exposure adjustable between 10 minutes and 24 hours based on the...
  30. H

    Stargazing Telescope for my astronomy class next semester

    :biggrin: I need a telescope for my astronomy class next semester :biggrin::biggrin::biggrin: and a $700 budget...having a difficult time deciding which one to get :-/
  31. Gliese123

    Stargazing Spectra Optics telescope 1400X150 questions

    Hello everyone! I bought a Spectra Optics telescope 1400X150 (reflector) for 260 Euro a few days ago and I had quite big expectations on it. The including oculars was on 25mm and 6.5 mm. But when I was going to look at Jupiter recently, then I didn't get a more visible view than a little dot and...
  32. M

    Stargazing Why is magnification defined as the ratio of eye and objective lens resolution?

    The telescope magnification is given by the measure of the resolution power of the eye divided by the resolution power of the objetive lens. I just want to know why a magnification can be defined as the ratio of these two kinds of resolution, I need a...
  33. C

    Stargazing Spatial and Angular Resolution of a Earth observing Telescope

    Does anybody know of a good reference for determining the required diameter of an Earth observing telescope's primary mirror? I am trying to find determine a rough estimate for a design I am working on. So far I have found the equation Sin\theta = 1.220 \lambda/D for angular resolution and...
  34. A

    Finding the lifespan of a telescope mirror (probability question)

    Homework Statement A telescope contains 3 large mirrors. The time (in years) until a single mirror fails has been investigated and we know that the probability that a mirror is still fully functional after t years is e^(-(t/10)^5 ) a) All mirrors must be working to take the most detailed...
  35. Orion1

    Stargazing What Discoveries Does the Very Large Telescope (VLT) Allow Us to Make?

    https://www.youtube.com/watch?v=wFpeM3fxJoQ VLT (Very Large Telescope)
  36. J

    Stargazing Vendor for telescope mirror cells?

    Any suggestions on vendors for good, well-designed reflecting telescope mirror holding cells, in the ~ 8" diameter range? I've had enough grief from the very poorly-designed cell that holds the primary in my 7" Mak-Newtonian, and am looking to toss it and replace it with something better. Tube...
  37. A

    Help Identifying Unclear Object Seen Through Telescope

    Hi, I'm pretty new at this amateur astronomy thing, and I saw something through my telescope that I could not focus clearly enough on (as to be expected from a telescope I picked up from craigslist for $10). I would like help identifying it. Latitude: 40° 15' 36" N Longitude: 74° 16' 27" W...
  38. R

    Stargazing Reflecting telescope principle and model please?

    can anyone please give me any resource for building a reflecting telescope (and also the underlying principles) (sorry if it's not the right place to ask)
  39. R

    Stargazing How to find the Point Spread Function of a Newtonian Telescope?

    Hi everyone. I am a research undergrad student at the University of Washington and I have been given a conceptual problem to figure out for my astrophysics group... My professor would like us to explain to how how one would find the point spread function of a Newtonian telescope. Here's...
  40. M

    Stargazing Hubble telescope, finite life?

    Hey, not sure if this is the correct forum but it seems physics will ultimately bring down the telescope. Why can't we leave the Hubble in space until it doesn't work anymore? It doesn't have any space crew to kill, it would break up on re-entree harming no-one and would continue to inspire our...
  41. Vorde

    Stargazing Upgrading my telescope, need advice.

    For some years I have had an orion skyquest 4.5 inch reflecting telescope that I received as a gift some years ago. I have recently gotten back into astronomy and have discovered that my current telescope isn't quite as powerful as I would like. Does anyone know what size mirror would be...
  42. S

    Stargazing House Appropriations Committee Kills James Webb Telescope

    Or it might as well be, the result would be the same. Dennis Overbye in the NY Times: http://www.nytimes.com/2011/07/07/science/07webb.html" According to this article (found on http://en.wikipedia.org/wiki/James_Webb_Space_Telescope" ), the project cost ballooned from $1.6 billion to a current...
  43. M

    Stargazing How Do Telescopes Show Us Distant Objects in Space?

    i just had an argument with a friend regarding the working of a telescope.Could you please help me out with it. ok the thing is that i say that the light of an object reaches the telescope then we r able to see that object which means that if we r lookin to an object which is 100 light years...
  44. Alain De Vos

    Stargazing Observing the sun with Newton telescope

    While making a projection of the sun on a paper with a Newton telescope, I’m able to see a white ball or to make burning holes in paper. My idea however is to be able to see something more spectacular , like sunspots or protuberances. Does someone has an ideas how to do this practically...
  45. R

    Stargazing Telescope Filters: Is Something Missing?

    I have a question about the colored filters used for the telescopes. Here I will give an example for the filters of the big telescopes, but I assume that it applies also to the smaller personal telescopes. The range of the visible light goes from about 400nm to about 750 nm. Where the "blue"...
  46. R

    Stargazing What telescope aperture is needed for spectroscopy of star clusters within MC?

    Hi, In research, if you want to observe a certain galaxy or cluster, how do you decide to which big telescope to apply (in terms of aperture), how do you know what aperture you need for a certain project? Thanks!
  47. AXidenT

    Astronomical Lens Telescope Problem - Angular Magnification

    Homework Statement A convex lens forms an image 8.96 mm on a screen. Keeping the screenand the object fixed, the lens is moved through a distance of 15.4 cm and a sharp image of the object is again observed on the screen. If the length of the second image is 3.54 cm, calculate the focal length...
  48. E

    View Saturn Through a Telescope: A Noob's Guide

    hi I am an astronomy nooby and i am trying to find saturn in my telescope, i don't know what seasons it is visible in, can someone help :D?
  49. L

    Stargazing What is the advantage of a binocular telescope (such as the LBT)?

    I"m wondering what is the advantage of a binocular as opposed to a single mirror telescope. I know that the advantage is supposed to be in terms of angular resolution, but I don't understand what that means and how to use this. If I look at the Wikipedia page on Astronomical interferometer, I...
  50. T

    Photons collected be telescope apertures

    the energy output of a star is such at the surface of the Earth it provides 5x10^-19 WM^-2 in the visible part of the spectrum... how many photons are collected per second by a 500mm diameter telescope? i don't know if there's any definite formula to drive the answer...but i tried this way...
Back
Top