Questions tagged [telescope]
Questions related to the physical instruments for astronomical observations.
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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 ...
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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 ...
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What are the benefits of a large refracting telescope?
Currently, refractor telescopes are limited in aperture because gravity will deform the main lens over time. According to Wikipedia the largest practical refracting telescope is 1m.
If we were to ...
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Can a telescope ever increase the apparent luminance of an extended object?
From what I know about common telescope designs, telescopes don't increase the apparent luminance of extended objects compared to the luminance seen with the naked eye. In this sense extended objects ...
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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 ...
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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 ...
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Is seeing the Apollo Moon landers via an Earth-based telescope that hard?
There are interferometers that fuse the images produced by multiple telescopes and achieve a resolution of 0.001 arcseconds. With changes, couldn't these observe the Moon landers? Is the reason why ...
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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 ...
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How did Michelson measure the diameters of jupiter's moons using optical interferometry?
In Betelgeuse: How its Diameter was measured (Chant, C. A., Journal of the Royal Astronomical Society of Canada, Vol. 15, p.133, Bibliographic Code: 1921JRASC..15..133C) the author says:
The paper in ...
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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. ...
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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 ...
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Why aren't reflector telescopes built with an offset secondary mirror?
Reflector telescopes (normally?) have a parabolic primary mirror that reflects the light to a secondary mirror which is placed at the center of the telescope. The construction holding that mirror and ...
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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 ...
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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 ...
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How can Mercury's sodium tail be imaged?
I recently learned that Mercury has a sodium tail. Can this sodium tail be imaged with a ground based telescope? Is so, what is the minimum setup required to be able to take a picture of it? Do you ...
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Which space telescope is the most distant?
From the earth, and from the sun. Only interested in active, operational ones.
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What are the deciding optical factors between a refractive and reflective space telescope optics as a function of aperture? (visible light)
Reading Yale News' Lighting a path to Planet Nine:
To detect objects that are otherwise undetectable, Rice and Laughlin employ a method called “shifting and stacking.” They “shift” images from a ...
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Why does this large Newtonian telescope's front cover have two or three holes in it?
The Michael Bernardo video How to use an Equatorial Mount for Beginners shows a large Newtonian telescope on an equatorial mount.
The cover of the telescope's large aperture shows what looks like ...
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Astromaster Celestron 130 EQ
I brought a new Astromaster 130 EQ and collimated it using a laser. However, whenever I try to observe moon I get a perfect picture but with other planets I see only a bright glowing ball which ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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.
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Why can't we build a huge stationary optical telescope inside a depression similar to the FAST radio telescope?
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 ...
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Why telescope mirror glass shipped as randomly broken chunks of a constant size in cardboard boxes?
The video MIRROR LAB: Preparing for Casting GMT's Mirror 6 shows the unpacking several hundred boxes full of broken glass from OHARA, packed in styrofoam.
The glass chunks are a fairly uniform size of ...
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What kind of things I could "see" with an amateur radio telescope?
There are apparently not many reasonably priced radio telescopes available for the amateur users. I only could find a SPIDER 230C 2.3 meter diameter compact radio telescope, which costs ~10 k€. ...
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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 ...
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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 ...
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What are the advantages and disadvantages of a 2-inch eyepiece versus a 1.25-inch eyepiece?
I'm considering picking up some new eyepieces for my telescope and am interested in comparing 2-inch and 1.25-inch eyepieces. Are there any disadvantages to 2-inch eyepieces? Are 2-inch eyepieces only ...
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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 ...
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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 ...
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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 ...
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What's the rationale behind the false colours in solar observation photographs?
Images from SOHO, SDO and other sun observatories are often coloured differently for different wavelengths or temperatures:
http://www.nasa.gov/mission_pages/sunearth/science/Sun-Wavelength-Chart....
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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 ...
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What is it about the layout of the three gratings in a Bahtinov mask that makes its indicate focus in this way?
The question Lucky imaging with Celestron 14 - is this result reasonable? includes a beautiful example of a focus test using a Bahtinov mask and the image below from Deep Sky Watch's Home Made ...
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How to make a 65 cm lens with a 20 cm hole in it for a Hamiltonian telescope?
This answer to What (the heck) is a Hamiltonian telescope? Is this one? confirms that the telescope in the question linked there is indeed as described and that the first lens is a full 65 cm aperture ...
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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 ...
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Minimum telescope needed to see the rings of the Saturn
I am a total novice. My daughter, likes Saturn. Since Saturn is so close I thought it was a good time to view it with her.
What are the minimum needed telescope specs?
Update: Can answer answers be ...
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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.
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Why is this telescope so short? How hard is it to make such a fast primary?
The recently discovered object C/2019 Q4 (Borisov) is in the news because it might have an eccentricity greater than one, which means it might be from outside the solar system, though not necessarily.
...
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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 ...
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