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27
votes
4answers
357 views

Telescopes to avoid as a beginner? [closed]

I've heard people talk about "department store scopes" or "trash scopes". How do I know what to avoid in a beginner scope? How can I know that I'm not getting something we will be more frustrated with ...
21
votes
3answers
877 views

How to determine what size telescope to buy

A couple of years ago my son showed an interest in astronomy and we bought a 6" reflector telescope. We use it pretty regularly and have enjoyed it immensely. Lately we've both been wishing we had ...
19
votes
2answers
603 views

Optimal telescope size?

Consider a diffraction-limited telescope with unobstructed aperture $D$. Such a scope is capable of yielding an angular resolution $\alpha$ that scales as $\lambda/D$, with $\lambda$ denoting the ...
17
votes
5answers
292 views

Why don't we have a better telescope than the Hubble Space Telescope?

The Hubble Space Telescope (HST) was launched in 1990, more than 20 years ago, but I know that it was supposed to be launched in 1986, 24 years ago. Since it only took 66 years from the fist plane to ...
15
votes
6answers
2k views

Lenses (refractor) or mirrors (reflector) telescope?

What differentiates, in terms of practical quality, not technical implementation, a refractor from a reflector telescope? Why would one prefer a refractor over a reflector, when reflectors come with ...
14
votes
2answers
957 views

What is the theoretical limit for farthest we can see back in time and distance?

13.2 billion years ago the universe was rather small, having started only half a billion years ago. Today, with the help of Hubble Space Telescope, we are able to capture the light of galaxies emitted ...
13
votes
5answers
2k views

Telescope for 6 year old and dad new to astronomy

What's a good telescope for my 6 year old? We're both brand new to telescopes in general, but love space, stars, planets, cosmology, etc. Happy to spend up to $200 to start. Maybe more for a good ...
11
votes
3answers
492 views

Why is this radio telescope's reflector spherical and not parabolic?

This is the Arecibo Observatory in Arecibo, Puerto Rico. Its reflector is spherical, measuring 1,001 ft. in diameter. It is considered the most sensitive radio telescope on Earth, but the fact that ...
11
votes
3answers
868 views

Can you damage your eyes viewing Venus?

Whilst I know it is extremely dangerous to view the sun using a telescope (or even just looking directly at it for prolong periods) can you do permanent damage to your eyes looking at Venus through a ...
11
votes
4answers
4k views

What does f/4.6 mean in a telescope and how important is this value? [closed]

In some specifications for telescopes, I saw a value marked as f/4.6. What does it mean exactly, and how important is when it comes to choosing a telescope?
11
votes
2answers
182 views

Could a mirror array used for thermal solar power plant double as a telescope at night?

I was looking at the Ivanpah Solar facility and it occurred to me that the large array of mirrors could double as some sort of telescope array at night. The climate in the desert would be ideal for ...
10
votes
4answers
3k views

Is building your own reflector telescope worth it?

I have always fancied building my own reflector telescope. I am wondering - For a certain budget, can you get better results with a home made rig? Or is this a folly, and really it would be better to ...
10
votes
2answers
147 views

How do air Cherenkov telescopes work?

The very highest energy photons, gamma-rays, are too energetic to be detected by standard optical methods. In fact they rarely actually make it to the surface of the Earth at all but interact with ...
10
votes
2answers
1k views

Observing Jupiter's non-Galilean moons

What strength of telescope is required to observe some of the non-Galilean moons of Jupiter? My current telescope at 50 magnification resolves the Galilean moons well, but I'm guessing it's far ...
9
votes
1answer
519 views

Why is the Ritchey–Chrétien telescope preferred in professional astronomy?

Hubble, as well as numerous other professional telescopes, use the Ritchey–Chrétien design. What optical and instrumental advantages does this kind of telescope have for professional astronomy?
9
votes
1answer
44 views

How do I use this 'Horizon Observatory'?

Just around the corner, we have one of these: It's at the Halde Hoheward (article in the German wikipedia), and it's called a 'Horizon Observatory' by the people who built it. How does it work ...
8
votes
2answers
490 views

What is exactly a Dobsonian, and what are the differences when compared with Schmidt-Cassegrain or Newtonian?

What is exactly a Dobsonian telescope, and what are the differences between this technical choice over a Schmidt-Cassegrain or a Newtonian configurations?
8
votes
5answers
97 views

Exoplanet detection via space-based parasol

I remember from watching Cosmos years ago, Carl Sagan suggested an interesting hypothetical method for directly seeing exoplanets. He proposed that in the 'future' we could launch a satellite designed ...
8
votes
1answer
370 views

Why are telescopes on top of Mauna Kea instead of Mauna Loa?

Many large and important telescopes are located on top of Mauna Kea on Hawaii. This is a great location for many reasons: it's tall enough to be above the weather, an inversion layer at night keeps ...
8
votes
4answers
1k views

How can I stabilize an unstable telescope?

I have an 80 mm refractor telescope on a tripod, but it shakes on every touch. It's very hard to see via 6 mm (x120) ocular. Even a little wind causes the image to become too unsteady. How ...
8
votes
2answers
842 views

How do you clean a dusty lens?

The lenses of my telescope and binoculars are dusty. What is the best way to clean them without damaging the optic coating?
8
votes
2answers
220 views

Why does a blue sky at dusk appear nearly black through a telescope?

Earlier this evening I was looking at the Moon through my cheap toy telescope (x150 magnification) when I noticed a (rather mundane) optical effect I couldn't explain. The Sun had just dipped below ...
8
votes
2answers
463 views

Smaller free remote control telescopes?

There are several online services that let you control a large telescope (eg, lightbuckets.com and slooh.com), even some that are free (eg, telescope.org). Unfortunately, the pay services are ...
8
votes
1answer
106 views

Where can I find information for how to create amateur radio telescope?

Where can I find good source of information for how to create amateur radio telescope. Particularly interested in creating Fresnel Zone Plate Antennas (aka flat dish). design, diagrams, ...
7
votes
6answers
839 views

Can any telescope be used for solar observing?

Can any telescope, such as a 8" reflector, that is normally used at night to look at planets be used or adapted for solar observing? What kind of adapters or filters are required or is it better to ...
7
votes
1answer
196 views

Why aren't there any arrays of visible light telescope?

There have been many radio telescope arrays which are capable of resolving stars significantly fainter than can be resolved with a single "small" radio telescope. Why don't they do the same with ...
7
votes
1answer
56 views

What size aperature would I need to find and see the supernova in M51?

On June 2, 2011, a new supernova was identified by an amateur French astronomer in M51. What size telescope aperture would one need to have any chance of seeing this? Given the right sized scope, ...
6
votes
4answers
65 views

Does the current light pollution set a fundamental limit for the range of Earth-based telescopes?

As far as I know, all deep-sky pictures are captured with the Hubble Space Telescope. If there would be no atmospheric distortion, could we make deeper pictures in the optical spectrum with ...
6
votes
4answers
141 views

Mixing and matching across eyepiece designs / manufacturers?

Right now, I am considering moving from 1.25" eyepieces to 2". While I'm convinced of the quality of the premium eyepieces, it would take me years to afford a complete set and, if I go that route, I ...
6
votes
1answer
1k views

What are the minimum telescope requirements to view a nice spiral galaxy?

I would like to view some spiral galaxy. However, I would prefer not to spend lots of $$$. What are the minimum specs a telescope must have to resolve detail in a spiral galaxy?
6
votes
1answer
272 views

How big of a telescope to view Gliese 581g in great detail?

I've always been interested in mega sized telescopes and how big they would have to be to see exoplanets in great detail. So, Gliese 581g is 22 light years away. Could we build a telescope in space ...
6
votes
2answers
179 views

If you focus in on one image, is combining two telescopes really equivalent to a larger mirror?

Have a look at this example: In addition, the Keck I and Keck II telescopes can work together as the Keck Interferometer. The 85-metre (279 ft) separation between the two telescopes gives them the ...
6
votes
1answer
138 views

What sort of equipment would I need to take a photo like this?

I'm interested in doing some astrophotography and I'm looking into the equipment needed to get a photo like this: http://www.flickr.com/photos/cscunha1984/6619321531/in/faves-heyvian/ I'm not looking ...
6
votes
2answers
1k views

How can I determine if my telescope mirror is parabolic?

This week I purchased the “Skywatcher Explorer 130P Newtonian Reflector Telescope”, specifically as it has the parabolic mirror. I do not have the outer packaging for sundry reasons. Therefore, after ...
6
votes
2answers
275 views

What makes a good set of binoculars? [closed]

After trying a bunch of binoculars at Star Parties and the like, I have a pretty good feel for about what aperture and magnification I'd like in a new set binoculars. I'm an eyeglass wearer so a long ...
6
votes
4answers
120 views

Automated telescope system

I am living up north in Norway, 300 km above the Arctic Circle, which gives me six months per year of darkness and cold. I used to have a starter telescope when I was living in Spain, but I gave it ...
6
votes
2answers
185 views

What's the best way to start out with astrophotography on a tight budget?

I'm new to astronomy and I don't have a great deal of cash to spend. I currently have a 3" reflector telescope which I've had great fun with. I also have a Pentax DSLR which I've been using to take ...
6
votes
1answer
159 views

Why is the Hubble Space telescope able to see farthest in the universe?

What determines how far a telescope can see in the universe? How does recording data for a very long time (~10 years) help? If we could build a telescope which work at microwave region, will it be a ...
6
votes
2answers
562 views

Optimal Angular Field of View (AFOV)

Given the rather huge price differences between eye pieces at the same focal length. How exactly does the AFOV affect the view seen through the eyepiece? Are higher / lower AFOV better for certain ...
6
votes
3answers
400 views

Is it possible to make a hydrogen-alpha solar scope?

Is the construction of an etalon / Fabry-Pérot interferometer within the reach of amateur telescope makers? Are there any resources pointing to such projects?
5
votes
5answers
52 views

Which current big Earth-based telescopes are equipped with adaptive optics?

I know only that the VLT is equipped with adaptive optics (AO) to bypass atmospheric distortion. Is it the only one, or have other telescopes been build with AO in the optical and infrared spectrum?
5
votes
1answer
528 views

What telescope would I need to observe Mars's polar caps?

What telescope refractor aperture size would I need to observe Mars's polar caps? I have a Levenuhk Strike NG 80mm, and I can see red disk of planet but cannot see any details on the surface.
5
votes
2answers
68 views

Could many widely separated space telescopes be combined for VLBI on IR/visible wavelengths?

I have read about ground-based Very Long Baseline Interferometry telescope arrays able to achieve huge resolution at IR/visible wavelengths. There are also space-ground VLBI configurations in ...
5
votes
3answers
182 views

Is it possible to surpass the diffraction limit for telescopes?

Telescopes have angular diffraction limit depending on the observed wavelength and aperture diameter. I've read that it's possible to go beyond the limit for microscopes. But is it possible to do the ...
5
votes
3answers
53 views

How to get started in Astronomy (UK based) [closed]

I have always been interested in space and astronomy (in my youth - I wanted to be an astronaut). However for various reasons, I never quite got started. I now want to get started - small but ...
5
votes
1answer
72 views

How to care for a Dobsonian around the ocean?

I live near the ocean where all the metal fasteners on a house quickly rust and am considering getting a large Dobsonian telescope but am concerned about the mirrors. Would keeping the dob inside a ...
5
votes
2answers
88 views

How many watts of light do instruments in modern telescopes need?

I just calculated that if the European extremely large telescope(978 m^2 area) would be pointed at the Andromeda galaxy once it is built, it will only get mere 1.2*10^-6 Watts of power from Andromeda. ...
4
votes
4answers
415 views

Can the Hubble telescope bring any star into focus?

Lets say I am talking about a view like this supernova - 13 billions light year away. In short can Hubble bring any star into focus in the entire universe? And if so, to what definition? I also ...
4
votes
3answers
304 views

Pleiades through a 15x 76 mm telescope

How clearly can the stars of the Pleiades cluster be seen through a 15x telescope (for example, FunScope)?
4
votes
4answers
783 views

Are telescopes with a concave lens useful for astronomy?

Are telescopes with a concave lens (instead of convex ones) ever useful for astronomy? And if so, where are they used? Do they ever affect resolving power?