Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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15
votes
2answers
18k views

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 ...
21
votes
2answers
126k views

How much magnification is needed to see 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. ...
9
votes
2answers
316 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 ...
10
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2answers
1k views

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 ...
3
votes
2answers
488 views

What is the maximum distance measurable with parallax? [duplicate]

What is the furthest star or celestial object whose distance has been calculated with parallax and how does it compare to the theoretical limit using today's telescopes? And how exactly does telescope ...
6
votes
2answers
197 views

What makes small interferometers useful? Like NIRISS on JWST

NIRISS is an instrument on the James Webb Space Telescope. It has a "non-redundant aperture mask" which obviously covers most of the area of the sensor. It seems to be advantageous for high contrast ...
7
votes
3answers
388 views

When did “resilvering” large telescope mirrors actually refer to aluminization, and why was it necessary?

This answer nicely summarizes the general picture of historical use of silver for mid to large size telescope mirrors, and the shift to aluminum once good quality vacuum pumps and chambers suitable ...
2
votes
1answer
201 views

What is the large astronomical instrument shown in this 1918 eclipse expedition photo?

This nice video musing about (among other things) the US Naval Observatory's $3,500 expedition to Baker City or at least Baker County Oregon to observe the June 18, 1918 solar eclipse, there is a ...
1
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2answers
153 views

Why does this Lowell Observatory telescope have so many knobs? What do they all do?

The Fox News article Arizona city played critical role in moon exploration history covers several interesting activities that took place in Arizona in preparation for the Apollo Moon landings. It ...
6
votes
1answer
825 views

Which type of telescope should I make?

I am not very much interested in observational physics but I just like to look at the night sky. It gives me a lot of inspiration. So, i was thinking about making a telescope for basic observations. I ...
6
votes
2answers
1k views

What should I look for in an astronomy tripod?

I have a Celstron SkyMaster 20x80 binoculars, and a tripod — Vanguard 263AT with a SBH-100 head. The binoculars weighs 2.2kg, while the head is rated to a loading capacity of 10kg, and the legs to a ...
4
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1answer
297 views

Any cheap (less than 100 euro) telescope for observing Jupiter? [closed]

The moon is not challenging. I would like to observe the big planets and their rings.
1
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2answers
6k views

what magnification is required to see jupiter, saturn, venus and mars with a 50mm refractor scope with f/12 ratio and 600mm focal lenth

i have a beginner telescope of 50mm and want to see planets it is arefractor with f/12 ratio and two eyepieces of 5mm and 10mm and i want to see mars, Jupiter, Saturn and venus. my max zoom ix 120x ...
8
votes
1answer
561 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
votes
1answer
254 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 ...
5
votes
2answers
1k views

Why can’t I see any detail on planets?

I really want to know why I can’t see detail on planets. This summer my Dad and I went on a trip to Utah I went outside to look at the planets and couldn’t see detail on Mars, Saturn, and Jupiter. ...
5
votes
3answers
483 views

How would a Fast Fourier Transform Telescope work without a mirror, dish or lenses?

I recently came across a short article mentioning the idea for a telescope built without mirrors or lenses that instead uses an array of antennas and massive computing power to resolve an image. Such ...
4
votes
4answers
234 views

Suggestions for a beginner-friendly telescope

I'm hoping someone can point me in the right direction for a beginner-friendly telescope for my family. My husband has mentioned wanting a telescope off and on for a few years, but he's never delved ...
3
votes
1answer
618 views

How does making a refracting telescope very long reduce the chromatic aberration of an uncorrected lens?

Below are two cropped views of "Johannes Hevelius's 8 inch telescope with an open work wood and wire "tube" that had a focal length of 150 feet to limit chromatic aberration." from Harvard University, ...
3
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3answers
267 views

Who invented the blink comparator?

The Wikipedia page for the blink comparator fails to mention who invented it. Many other pages extol the importance of the device, but we cannot find any mention of an inventor. Wikipedia does ...
2
votes
1answer
844 views

What is the faintest magnitude a telescope can see?

This website claims: The space telescope can detect objects as faint as 31st magnitude... It's referring to Hubble, but does not cite any source or math. How do you calculate the faintest (...
2
votes
2answers
214 views

How do I see more than just points in the sky?

I just bought a new telescope with these specifications: Aperture: 203 mm Focal Length: 1200 mm F/ratio: f/5.9 I usually use a 28 mm eyepiece, giving me about 42.5x magnification, but I also have a ...
2
votes
3answers
210 views

How did Johannes Hevelius' long telescope work? Why all the round holes?

The drawing below, found in Wikimedia and at lib.harvard.edu is of a very long tubed aerial telescope. I believe it is taken from his 1673 work Machinae coelestis. I've always wondered about the ...
8
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2answers
1k 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 ...
25
votes
4answers
7k views

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 ...
11
votes
2answers
3k 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.
6
votes
1answer
586 views

What kind of telescope do I need to see most of the Jupiter's moons?

I have a simple Newtonian reflector telescope. Using it, I am able to see the Galilean moons of Jupiter. However, Jupiter has much more moons than that (Wikipedia says 67 have been discovered this far)...
3
votes
1answer
522 views

Please Guide me to buy my first Telescope [duplicate]

I am a beginner and I've planned to buy a telescope(Newtonian reflector)for viewing planets and deep sky objects. As far as I know the most important factor to get a brighter view is that the ...
6
votes
2answers
223 views

Why not us interferometry to take a picture of Pluto?

Interferometry is among the best ways (if not, the best way!) to have an image of a very distant object. Recently a picture of the black hole at the center of M87 was released. It is the result of ...
5
votes
3answers
8k views

Do bigger telescopes equal better results?

There are many large reflecting/optical telescopes around the world, just to name a few: the Very Large Telescope, Large Zenith Telescope, and European Extremely Large Telescope. My question is does ...
5
votes
1answer
697 views

What's a good step up from 7x50 binoculars?

I own a Nikon OceanPro 7x50 pair of binoculars, but I find that when I look at the moon, I would like more magnification. My requirements are: costs less than $400 weighs less than 10kg the length ...
4
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3answers
3k views

First night on a telescope questions

So I recently got into astronomy and I am using my fathers old Meade EQ1-B reflector telescope. This is my first night using it and I have come across a few questions. To begin, the telescope was left ...
2
votes
0answers
47 views

Within a given image of a multiple-image producing gravitational lens, does Fermat's principle apply?

The question Does gravitational lensing provide time evolution information? is excellent! When we see multiple images of the same object because of the phenomenon of gravitational lensing, do all ...
11
votes
3answers
467 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 ...
9
votes
4answers
308 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
votes
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 ...
8
votes
1answer
276 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 ...
8
votes
1answer
305 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
votes
4answers
344 views

Where exactly is the modification that first corrected the spherical aberration in Hubble's primary mirror?

The April 2015 CBS News article How NASA fixed Hubble's flawed vision - and reputation describes the modification taken to the Hubble Space Telescopes by the Space Shuttle that was used to correct for ...
6
votes
4answers
270 views

Why not use only one support vane for the secondary mirror, to avoid multiple diffraction spikes?

Each vane holding the secondary mirror in front of the primary causes a diffraction spike. Couldn't the secondary mirror be held with only one vane? If stability is the issue, couldn't it be ...
6
votes
5answers
767 views

Could mirrors be replaced with CCDs?

Why do telescopes use mirrors that simply reflect photons, when they instead could be covered with large sensors to register them? Reflection is all good and well, all thanks to silver and beryllium ...
6
votes
1answer
284 views

If we had the right technology could we see a distant star in detail?

If, for instance, Hubble's camera was a 10^300 times better could it see a distant star in details or is there a limit to the amount of light that reaches the earth's orbit or perhaps does the light ...
6
votes
2answers
221 views

Ninth planet - what else could it be?

So recently it was announced that there might be a ninth planet out there. Some people (from NASA) say the odds are 50% that it is a real planet, since it hasn't been discovered by telescopes yet. ...
6
votes
2answers
190 views

Do we know at which angle the Event Horizon Telescope will look at the accretion disk of Sagittarius A*?

Do we know at which angle the Event Horizon Telescope will look at the accretion disk of Sagittarius A*? Additionally, would it matter if we are exactly in the plane with the accretion disk, i.e. ...
6
votes
1answer
74 views

Occultations of Triton

I've been listening to an episode of the "NASA in Silicon Valley" podcast about the SOFIA mission. One of the techniques they use at SOFIA is stellar occultations to study different objects. My ...
6
votes
1answer
165 views

How does the black hole at the center of M87 look like in the visible spectrum?

I learned here that the picture of the black hole we saw all over the news was a false color image, based on the radio spectrum emissions. How would the black hole at the center of M87 look like when ...
5
votes
1answer
641 views

Why when we look through a telescope in space, do the billions of stars not block our view from seeing further?

I know that we are able to "see back into time" by looking very far away through telescopes such as the Hubble telescope, but my question is, wouldn't you run into at least a couple of stars that were ...
5
votes
1answer
152 views

Which space telescope is the most distant?

From the earth, and from the sun. Only interested in active, operational ones.
5
votes
2answers
414 views

A smudge near Jupiter

I was looking at the Jupiter for the first time today and I have noticed a smudge near it. Could someone explain what it is, please? I was looking online but did not find anything. So I thought that ...
5
votes
1answer
354 views

Was the use of silver on 'optical' telescope mirrors more common in the past? Why?

In the past, weren't many astronomical telescope mirrors periodically removed and 'resilvered', and wasn't this actually done using silver? I'm guessing that this is much less common now - new ...