Telescope Definition and 517 Threads

We can see galaxies/planets light years away determine their composition such such as if they have water et cetera. My question is if light takes billions of years to reach us from there how is that we can determine such things? Is the speed at which a telescope can zoom faster than the speed at...

Andromeda galaxy is measured as about 2,500,000 light years from me as I am at rest with respect to the Earth. Using luminosity of known objects in Andromeda. I have a close to light speed spaceship which is pointing toward the Andromeda galaxy with a camera mounted on the nose cone. I am going...

I just recently got a dobsonian reflector telescope, (Orion SkyQuest XT8 PLUS Dobsonian Reflector Telescope) and I was wondering what the best way to see the andromeda galaxy would be using the telescope? Of these, which would be the best eye piece for that sort of thing?: Orion 2" 28mm...

Its an often prøven fact that a convex lens focused rays parallel with the optical axis into the focal point of the lens, but what about rays that are parallel with each other and with a small angle to the optical axis? In ray diagrams with telescopes (such like the one below) one often draws...

Hello, I've bought a skywatcher refractor 1025AZ3 with D:102mm F:500mm but unfortunatlly i wasnt able to get into my country so i have everything except the tube, so i decided to build the tube..do u know how i can find the construction instructions to build this tube or is it possible to build...

Hi I am very much interested to build a telescope on my own. I am looking for a complete guide to build a telescope and getting the apparatus needed ? Thank you in advance for all suggestions.

I've had a telescope for a few years. I know pretty basic stuff - and I can easily find planets when they are in the sky (mostly because I know Venus is around sunrise/sunset, and Jupiter & Saturn are non-twinkling bright objects in the sky). I know a few constellations - Cassiopeia, Orion, Ursa...

not to hijack - but seems not worth a separate thread. Is it possible to clean a telescope mirror? About 30 years ago i bought Dad a 6" Meade mirror out of Sky&Telescope magazine. We built a simple Newtonian with a redwood twelve sided tube. Local astronomy club deemed it "handsome" which...

I posed this question in a thread in the GD forum because I had not yet seen this thread and, wretched creature that I am, I neglected the search tool. Anyway, regarding beginner telescopes, I thought some of you might be able to provide some insight. I read that a good beginner range is a 60-80...

Right so I'm looking to buy my first telescope and rather than start a thread I thought I'd post here. How does this look for a beginner telescope? Keeping in mind its my first and I really only want to look at the moon, some of the closer planets, and maybe some nearby galaxies or nebulae. I am...

Homework Statement Suppose a simplified telescope and grating spectrometer system: D is the telescope's primary diameter, W is the width of the collimated beam, β is the grating angle in a Littrow configuration, and \alpha is the aperture diameter in angular units on the sky. The goal is...

Hi, I am interested in purchasing a telescope, although I am not very familiar with the parts and overall structure. introductory feedback, and recommendations would be much appreciated, and also I don't want a budget of $500 (preferably price range $350-$450).

Hi I am trying to figure out if there is call for a small, commercial, educational radio telescope to measure the 21cm emission line of hydrogen. We have been developing an instrument with the following characteristics: - The antenna would have a size of about 1m x 1m. Because the...

Hey, I'm trying to start learning about astronomy with my brother's old telescope and I need a little help in getting started :). Firstly, what my textbook tells me is that the declination scale shows a scale of numbers which go from zero to nine and then back down to zero again, however I...

Hi, Iam thinking of making my own telescope and I have a magnifying glass lens, biconvex, about 10 cm in diameter and 27 cm focal length. I think it would be better as the objective. For the eyepiece, what type of lens, of what focal length and aperture diameter should I use? (I hope to identify...

Is my telescope "compatible" with my latitude? I have a Newtonian Celestron Astromaster 114EQ (CG-2 equatorial mount) and the manual says: "The Astromaster CG-2 mount can be adjusted from about 20 to 60 degrees [...]". The latitude where I'm is -15º. What does this excerpt means for me. I...

Homework Statement When viewed from Earth, the Moon subtends an angle of 0.5° in the sky. How large an image of the Moon will be formed by the 3.6 m diameter mirror of the Canada-France-Hawaii Telescope, which has a focal length of 8.5 m? Homework Equations 1/s + 1/s' = 1/f, but I'm...

In the Hubble Space Telescope, light rays from a distant celestial object (1) first passes through an aperture window of diameter 3m (2) incident upon, and reflected by a primary mirror of diameter 2.4m (3) reflected by a secondary mirror of diameter 0.3m to form the final image. For the...

Homework Statement I am seeking a derivation of the formula for greatest detail or maximum resolution of an astronomical telescope, which is: Homework Equations M = fo/foe where: M: magnification fo: focal length of objective lens foe: distance of primary image from the eyepiece...

Is it possible for a telescope to resolve images beyond the diffraction limit? In other words, is the information in the light entering a telescope insufficient to resolve beyond the diffraction limit, or is information lost when the light is focused onto a screen? Attached to this post is a...

I just posted about the new parameters here: https://www.physicsforums.com/showthread.php?p=4152380#post4152380 Basically the new numbers look rather close to what Jorrie already put as the default in his calculator. zEQ looks familiar. Hubble rate 70 looks familiar :biggrin: Here's the...

Okay so I want to make a telescope at home... Im not a noob. Even if I am please just help me. I've got a couple of magnifying glasses ..pretty big .. I don't know the exact focal length... But one of them is twice the size of other... As soon as the sun comes up I'll find their focal...

Alright, I know about optical telescopes, but I haven't a clue how a radio telescope forms an image. I'm used to pixels on CCD's measuring photon counts, but how are the radio waves detected and an image created from them?

http://www.innovations-report.de/html/berichte/physik_astronomie/inauguration_ceremony_h_e_s_s_ii_telescope_203113.html?utm_medium=twitter&utm_source=Innovations-Report World’s largest Cherenkov telescope opens. Does anyone know what it is meant to study and what it expects to see? I felt...

Can anyone suggest a guide or books for making a telescope, DIY style. Also what size would be appropriate for a first attempt, and how much might it cost it you have any ideas. Thanks!

Hi. I am new to PF. I am an incoming high schooler with an interest in astrophysics, and a friend and myself are working on building a telescope (not a very sophisticated one, just one that can reveal the craters of the moon and the satellites of Jupiter). I am curious to know if any amateur (or...

Hello! I am preparing an exam about optics and I can't understand a formula.my problem is at the end of the second page (the explanation is in Italian, but the formulas are easy to read for everybody). I can't understand how in the last step f=R/2 - (1+b) * r^2/4R etc they found -(1+b)...

Our Universe is 13.5 Billion Years old approximately. Till now Hubble telescope has discovered galaxy at 13.2 billion light-years ago. Is it possible for James Webb Telescope to discover object or galaxy prior to 13.5 Billion Years old?

I haven't ever used a telescope. I wanted to know about this one. Like what all can we see using it ? like which planets/moons, if at all ? link for the particular telescope is http://www.sirindia.com/Original-Tasco-30-Power-Telescope-with-Table-Top-Tripod.html?SecID=0

Homework Statement From Optics by Frances Sears, 1949, Chapter 6, Problem 11: (I've been working all the problems in the book on my own.) A crude telescope is constructed of to spectacle lenses of focal lengths 100cm and 20cm respectively. (a) Find its angular magnification. (b) Find the...

what creates the "star points" in telescope pictures of stars? it's a basic question. e.g. see this hi-rez Hubble Deep Space pic: http://upload.wikimedia.org/wikipedia/commons/9/9b/Hs-2004-07-a-full_jpgNR.jpg i count about three bright objects with pointy cross-like projections from...

Homework Statement What type of location for a telescope would be needed in order to oserve the emissions of the dying VY Canis Majoris? The material is rich in dust and molecules that would vaporise around hotter stars and emits infrared radiation. Homework Equations N/A The...

a bit random to this but could any of you give me an example aperture for a telescope collecting ISO far-infrared radiation. (to assist a theory about Andromeda)

Homework Statement A Cassegrain telescope has a 500mm diameter , a focal length of 5000mm and a central obstruction of 80mm diameter. Calculate: 1) the magnification with a 25mm eye piece 2) the light gathering power compared to aye of 5mm in diameter 3) the angular field in the sky if the...

Hello , i have a jessops 800-80 astronomical telescope and i was wondering how to make it more stable because when i was viewing saturn in virgo i was looking at it the a gentle breeze came and it just went wappy and the same when i was viewing the moon . so i thought is there a way to make it...

Homework Statement My prof mentioned that if a telescope has a bigger aperture, you can generally resolve the image better. He did mentioned the reason but I kinda forget the reason so can someone tell me why bigger aperture allows you to better resolve images??

As the title. How many precent of the entire sky is investigated by the kepler telescope? I'm aware of that it's very little, but does anyone find a good page of this? I've looked, without results. I'm very thankful for help! :biggrin:

Homework Statement "Your vacation cabin in the woods is at the very fringe of the reception area for the FM radio station in the previous question (that broadcasts at 100 mHz). In order to maximize your chances of receiving your favorite tunes clearly from this station, you should adjust the...

Homework Statement Vague class discussion. Stars are points and a telescope does not magnify them. How then can more stars be seen with a telescope? Homework Equations I know magnification for a telescope is fo/fe but that is not much help The Attempt at a Solution Is it because...

Homework Statement a) what is the angular size of the moon as viewed from the Earth's surface? b) The objective and eyepiece of a refracting telescope have focal lenghts 80cm and 2.0cm. What is the angular size of the moon as viewed though this telescope? mean radius of the moon-...

Hi I am trying to design a three mirror off axis telescope. The free parameters are the offset between the apertures and distance betwen the surfaces. My question is for a system with 'n' elements/surfaces (n=3 in my case) is there a relation between optical path length and focal length of...

I have done a lab on resolution power of a telescope. a wire gauze was placed infront of sodium lamp and i used a telescope with adjustable vertical slit to look at it. i was bit confused with the theory .. 1) I was told to record the slit width when the vertical wires just cease to be seen...

Hi i am new to this forum so i apologize if I've posted this in the wrong place. I have brought my first telescope: http://www.celestron.com/astronomy/telescopes/celestron-skyprodigy-130.html I have a puzzling problem though witch I am sure u guys will know the answer to. I paid a lot of...

I am helping my son design and build a refractor telescope for a science fair project (8th grade). He has read some on lens types and focal lengths. We also read that Galileo's most powerful telescope was 33x, and was able to view Saturn's rings and Jupiter's planets. We want to be able to do...

Homework Statement it gives a bit of an intro "It is difficult to build a large surface area telescope to observe X-rays, because the index of refraction for nearly all materials at those wavelength is less than 1, which means you cannot create a reflective mirror in the normal fashion...

Which one is better for general non-professional star gazing, Reflecting Telescope or Refracting Telescope? I live in sub-urban area, not that much light/air pollution.

Hey all. I know that the maximum resolution of a telescope directly relates to the size of the aperture and the wavelength of the light. What I'm wondering is what would happen if you took "pieces" of a much larger mirror from opposite edges and just used those pieces. Pretty much what this...

Homework Statement Hi all. This is for a piece of Design coursework to design a rowing machine. I want to have the central beam the seat slides on be constructed from four individual beams the can telescope down, each with a single welded support. I'm really struggling on starting my...

Hey PFers. I'm just wondering what your thoughts on a High Altitude Telescope are. What I mean is pretty much a telescope on a platform suspended in air on balloons at 40,000+ feet. The whole thing would be solar powered, with a couple of engines capable of station keeping, with the appropriate...

So far, I've had a Orion SkyScanner 100 for about 2 months, and I love it. I go out any time the weather is clear, and blast Bob Marley while I watch the stars. Since Christmas is coming up, I plan on getting some spare cash, and have decided I would like to buy a mid priced telescope...