Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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49
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3answers
26k views

How powerful a telescope would allow me to view the astronauts aboard ISS do a space-walk?

This arose from a comment posted against a question elsewhere on the stackexchange How powerful a telescope/binoculars would allow me to view the astronauts aboard the ISS do a space-walk? Aperture? ...
38
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4answers
9k views

Why are we building larger land-based telescopes instead of launching larger ones into space?

This question is a follow-up to Do bigger telescopes equal better results? How much bigger does a ground-based mirror have to be to match what a space-based one can do? I guess I'm asking primarily ...
30
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4answers
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What will succeed the Arecibo Observatory?

Just a few minutes ago, I got a notification from Space.com stating that the Arecibo Observatory will be, sadly, decommissioned due to extensive damage to its structure. So, with the loss of one of ...
29
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5answers
8k views

Is it possible to mount a telescope on a plane? Is it beneficial?

I was wondering if any planes had mounted telescopes with the intent to observe the stars. I understand that the atmosphere itself can warp and hinder incoming light and even completely obscure views ...
26
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4answers
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What would happen if someone had a telescope and watched Betelgeuse when it goes supernova?

Would that person go blind? Neutrino detectors and the abundance of Neutrinos would detect the upcoming visible show about 3 hours before any visible signs, so there would be time to point certain ...
25
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4answers
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Shouldn't this cause a fire?

This website shows a telescope projecting the sun onto a blackboard: https://astronomyconnect.com/forums/articles/2-three-ways-to-safely-observe-the-sun.21/ Why isn't the board catching fire? You ...
25
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5answers
3k views

Is it possible to do planet observation during the day?

Keep in mind I'm just a newbie. So.... I have a new Newtonian telescope. It has 150mm opening and 1400mm Focal Distance on top of an equatorial mount. I have 25 and 10 mm eyepieces... and a 2x Barlow. ...
24
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2answers
6k views

What detail can Hubble see on Mars?

I'm researching a scene for a sci-fi novel in which the near-future protagonists observe earth through a station-mounted telescope in Mars orbit. My goal is to understand how much detail they ...
24
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2answers
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How much magnification is needed to see the planets of solar system?

I have a 3inch Newtonian reflector telescope with 300 mm focal length. I can use highest magnification of 75x using a 4mm eyepiece. But in 75x I can't see the details of Jupiter what was expected. ...
23
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2answers
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Please check my Mars photo

Hi built my own newtonian telescope for the first time. Up until that point I had never used a telescope. Can you please look at the photos attached and tell me if this is what Mars should look like ...
21
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3answers
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Should I focus more on Aperture or Focal Length for a telescope?

Let's assume there are three types of telescopes with the following specifications: ...
20
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7answers
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How can we focus radio telescopes on a star when the earth is spinning?

Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange ...
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2answers
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Why are wavelengths shorter than visible light neglected by new telescopes?

The diagram below, which I stole from this post by @HDE226868, shows that angular resolution as a function of wavelength suddenly drops by three orders of magnitudes from visible to UV-light. The ...
19
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1answer
4k views

Is there any telescope on Earth that can see the lunar rovers on the moon?

If I have the right numbers, it seems to me that even Hubble telescope might barely be able to make out a carcass of a blue whale on the surface of the moon, which puts objects as small as the lunar ...
16
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3answers
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Why different specifications for telescopes and binoculars?

Sorry for the noob question but I don't seem to be able to find the answer on the internet. I've been looking through some telescopes and binoculars and noticed that shops typically give different ...
16
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2answers
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How do satellites impede current telescopes?

As we send up more and more satellites, it stands to reason that our view of the universe becomes more and more obscured. I would certainly expect for example that a large telescope such as the LSST ...
15
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8answers
11k views

Determine the moons of Jupiter through a telescope

I was doing my own "space exploration" last night with a telescope. Being a space noob I can't visually determine stars or planets (I know the moon, though), but I focused on one particularly bright ...
15
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2answers
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A good telescope for the viewing of Nebulae, Stars and Planets

So, I am a 15 year old interested in astronomy. My father used to have a reflector telescope, but was never so serious about it that he could recommend me a good telescope. I am looking to buy a ...
15
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1answer
1k views

How Does a Refractor Telescope Work?

As I understand it, the difference between a reflector and a refractor is that a reflector uses mirrors on the back to reflect the light to the secondary mirror then the secondary mirror reflects the ...
14
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2answers
2k views

Space telescope located in outer solar system

I want to pose a question from someone who's astronomy knowledge would fit neatly onto a single piece of paper so please bear this in mind with any comments or answers. I am interested and want to ...
12
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4answers
843 views

Using the Sun as a Gravitational Lens

Can the Sun be used as a gravitational lens to achieve better telescopic viewing? Can this effect be practically used to view celestial objects?
12
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2answers
227 views

After Oumuamua passage, has an “urgency” telescope time request procedure been set up?

During the rapid passing of ʻOumuamua through our solar system, it was difficult to get instant telescope time. Usually, formal requests and a review process are necessary before telescope time is ...
12
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1answer
160 views

Does the Reflection Method for Looking at the Sun Work For Refractors?

I own a newtonian reflector and occasionally use it (using the reflection method with paper) for looking at the sun. I happen to also own a refractor, but I'm not exactly sure if the reflection method ...
11
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3answers
677 views

What was the largest telescope ever fitted with an eyepiece

Serious modern telescopes use CCDs to capture the results. This makes it convenient to process or display the results halfway around the world. However, there is something visceral about looking ...
11
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3answers
529 views

What limits the usable focal length of telescopes currently?

What barriers - of technology, physics and possibly economy (things that would be possible technologically but are simply too expensive) sets the upper bound on quality of telescopes for observation ...
11
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1answer
897 views

Recording Spectral Lines at Home

I was wondering if it would be possible to record the emission/absorption spectra of stars without expensive spectroscopy equipment. Would it be possible to somehow utilize diffraction grating? I own ...
11
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2answers
4k views

How does a telescope measure parallax angle?

I know how stars' distances are measured by using parallax, but I want to know how the actual telescope measures the parallax angle. Any helpful links/ explanations are needed.
11
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0answers
280 views

Method to determine the amount of reflected starlight necessary for an exoplanet to be visible from a given distance/angle? [closed]

What is the method to determine the amount of reflected starlight necessary for an exoplanet to be visible from a given distance/angle? (Not from occlusion but actually visible on its own.) Further, ...
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4answers
3k views

Why can't we build a huge stationary optical telescope inside a depression similar to the FAST?

So first we'll have to find a natural depression or we should create one. I understand you can only see a single portion of the sky since it can't be moved, so my money is on creating an artificial ...
10
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2answers
1k views

Could we parallax measure stars just based on the Earth's size?

Imagine two major surface observatories, perhaps the "northermost" and "southernmost" such (ideally on a similar longitude). For nearby stars, could they each take a photo at the same time, and ...
10
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2answers
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What (actually) is the “ deprojected half-light radius” of this almost-all-dark-matter Galaxy?

The recent news of the Ultra Diffuse Galaxy (UDG) Dragonfly 44 is an excellent example of what could be termed 'observe different' thinking. The dragonfly telescope is noted not for the size of its ...
10
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1answer
420 views

Why does squinting make hard-to-see objects clearer?

So I, like most other astronomy enthusiasts, have, at some point, not been able to see something clearly, such as a star, and have had to squint to be able to see it better. When this happens, the ...
10
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1answer
291 views

What are the next planned space telescopes?

We've had hubble for two decades. Its become the most famous space telescope, and lately Kepler seems to be running for the second place. Are there any more powerful, better telescopes planned for ...
10
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1answer
246 views

What is the bluest narrow band filter mounted on ground based telescopes?

If we want to check a QSO's lyman alpha narrow band image, could a ground based telescope do that? I mean under the circumstance that its lyman alpha shifts to 3300A.
9
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4answers
598 views

Why are telescope mirrors made of glass?

Optical telescope mirrors are typically made from endlessly polished glass surfaces that have been aluminised to provide a very smooth surface of reflective aluminium. But why the need for glass at ...
9
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3answers
1k views

Why are radio telescopes shaped so differently than optical telescopes?

Why are radio telescopes typically only a dish with a receiver above it, while optical telescopes have a primary, plus secondary and sometimes even a tertiary mirror? In other words, why do radio ...
9
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1answer
3k views

Theoretically, what is the biggest optical telescope that may exist?

Recently, I read yet another news about E-ELT. It will have 39.3-metre-diameter segmented primary mirror. And I was interested in the next question: Theoretically, what size of the primary mirror (...
9
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1answer
277 views

What is a quaternary mirror and why does the E-ELT need one?

In this recent BBC article I read the one-sentence paragraph: "Development on the mirrors - in particular, a very complex quaternary mirror - continues apace." and became interested in the ...
9
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3answers
186 views

Why are telescopes positioned in Lagrange points?

In this Wikipedia article about the list of space telescopes to be launched (which I assume is exhaustive), of the 11 telescopes yet to be launched, 6 will be positioned at the Sun-Earth L2 Lagrange ...
9
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2answers
351 views

Is it possible to figure out your location in the Milky Way if you are suddenly wormholed to a random, distant location in the galaxy?

If you were flying along in your spacecraft somewhere in our solar system and then a large, stable wormhole suddenly opened and you flew into it and were whisked away to some distant location in the ...
8
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2answers
752 views

Which telescope's model is being shown to Albert Einstein in this file footage? What event might this be?

In the Economist video Why does time pass? there is some file footage of Albert Einstein attending some event where a model of a large telescope is on display, and being described to Prof. Einstein. ...
8
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5answers
296 views

Why was the (small) Hubble better able to find KBO targets for New Horizons than large adaptive optics ground telescopes?

When initial searches for a Kuiper Belt object for New Horizons to fly to after passing Pluto did not find good targets, the Hubble telescope was used, and it resulted in the current targeted flyby ...
8
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1answer
838 views

How can I observe Sgr A* with itelescope.net

I've been experimenting with itelescope.net and tried to observe Sgr A*. I was wondering if there are any suggestions how I can best observe the surrounding stars.
8
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1answer
682 views

Plot of best available resolution vs wavelength - radio through gamma rays?

What I'm looking for is a graphic that shows in a general way the best available telescope resolution vs wavelength throughout the entire wavelength spectrum. So for example, there might be two very ...
8
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2answers
2k views

Selecting a Telescope for Viewing Planets

I hope to observe planets like Jupiter and Saturn, and moons. I am a novice when it comes to telescopes and I know images in magazines are not taken with at least 12-inch telescope in a middle of ...
8
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2answers
465 views

Why aren't secondary mirrors offset to get rid of diffraction spikes due to the support vanes?

Some kind of ellipsoidal shape mirror could reflect to a secondary mirror which is not in the way of the infalling light. Two advantages are immediately obvious. The primary mirror would not be partly ...
8
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4answers
2k views

Can we see the color of nebulae?

Someone asked me this question: To see the color of the Great Nebula in Orion, how large the aperture of the telescope should be. I don’t even know whether this is possible. I understand that the ...
8
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1answer
326 views

Is there a cosmic, rather than technological, upper limit to what a telescope can resolve?

Space radio interferometers could have a baseline of millions of kilometers, but is there a point where a larger baseline doesn't improve the resolution anymore because the photons observed are ...
7
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3answers
537 views

Can we visually perceive exoplanet transits with amateur telescopes?

Is it possible for an amateur astronomer to visually perceive an exoplanet transit by the change of brightness of the star via observations spaced over time, or is the variation of the brightness too ...
7
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2answers
1k views

Jupiter with a mobile phone and Celestron Astro FI 102mm Maksutov

My name is John, I am new here and now that I am retired I decided to get myself my first ever telescope, why I never got one before I have no idea...probably too busy. So I thought I would try and ...

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