The science dealing with objects and phenomena located beyond Earth. In particular, this applies to observations and data. At its core, astronomy is the physically informed cataloging and classifying of the contents of the universe in order to better understand what is out there.

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19
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5answers
2k views

Does the Moon's core still contain significant heat?

On earth, using earth-sheltering techniques can significantly reduce the temperature fluctuations on a structure. Would the same statement be true as well on the Moon? Does the Moon's core still ...
15
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5answers
3k views

What do the colors in false color images represent?

Every kid who first looks into a telescope is shocked to see that everything's black and white. The pretty colors, like those in this picture of the Sleeping Beauty Galaxy (M64), are missing: The ...
10
votes
2answers
5k views

Cameras in Voyager probes

I've always wondered about the cameras in the space probes, especially in the Voyagers. 1) What kind of cameras do they have? Digital? (What kind of sensor and megapixel count?) Analog? (Do they ...
2
votes
2answers
296 views

Why can't you see meteors, but you can see comets from the moon?

Why can't you see meteors from the moon and why can you see comets?
10
votes
1answer
230 views

How many earth-sized planets have been discovered outside the solar system?

How many earth-sized planets have been discovered outside our solar system? Is there a combined registry of them anywhere? Where might I look for more information?
8
votes
4answers
391 views

Shapes of galaxies

I've heard most of galaxies are spiral or ellipsoid shaped. Is it true? If true, then why they form in such shapes? How did arms of the spiral galaxies form?
19
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4answers
10k views

How do astronomers measure the distance to a star or other celestial object?

How do scientists measure the distance between objects in space? For example, Alpha Centauri is 4.3 light years away.
13
votes
3answers
251 views

How are newly discovered objects (stars, planets, galaxies…) named?

When a new astronomical object (star, planet, galaxy, comet, etc.) is discovered, what is the official procedure to name it? Who decides about the name of it? Can they be changed in time? Extra ...
4
votes
1answer
32 views

Are solar physics images of use to the night-time community?

I'm actually interested in cases of cross-discipline data re-use. I know that the SOHO/LASCO coronographs are used for comet finding, that solar telescopes were used to get information about Venus's ...
12
votes
2answers
162 views

What is the most distant object from the Earth that a spacecraft has visited to date?

What is the most distant object from the earth that a spacecraft visited has visited so far? What was the mission and when did it happen?
11
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3answers
3k views

Calculations of apparent magnitude

I was attempting to do some calculations of apparent magnitude to help solidify my understanding of the topic, but have been running into some confusion. According to Wikipedia, the apparent ...
7
votes
2answers
83 views

What latitude is needed before you can reliably see Omega Centauri?

What latitude is needed before you can reliably see the globular cluster Omega Centauri, say it reaches 20 degrees above the horizon? What about if you are up on a hill looking down, what's the ...
6
votes
3answers
714 views

Binary stars' apparent magnitude

If you plot the apparent magnitude of a binary system (so you are unable to see 2 distinct stars) against time, it gives a repeating 'M' effect. (from http://accessscience.com/) Assuming one star ...
8
votes
2answers
2k views

What does the sky look like to human eyes from orbit?

There are numerous pictures, obviously, of the blackness of space from the shuttle, the space station, and even the moon. But they all suffer from being from the perspective of a camera, which is not ...
11
votes
5answers
11k views

What is an asterism compared to a constellation?

I'm doing an astronomy exam tomorrow and in the practice paper it asks for the difference between constellation and asterism. It seems asterism is a group of recognizable stars; however I thought that ...
8
votes
2answers
665 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 ...
9
votes
1answer
1k 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?
5
votes
1answer
50 views

How does atmospheric seeing evolve over time?

I am writing an automated target selection application in which the seeing at the time of observation is an important factor: some fields are important to observe under good seeing, others, less so. ...
10
votes
2answers
200 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 ...
6
votes
2answers
181 views

In what ways can a lunar eclipse occur?

In what ways can a lunar eclipse occur? Also, on what percentage of the Earth are they usually viewable? I am aware that there are multiple configurations that constitute a lunar eclipse (umbral, ...
11
votes
4answers
112 views

What's the best way to watch meteor showers?

I have read somewhere that the best/easiest way to watch meteor showers is to lie on the ground or other horizontal surface with your feet oriented towards the "apparent point of origin" (what was ...
13
votes
5answers
144 views

How do you respond to questions like “Have you ever observed a UFO?” [closed]

This is a question that astronomers get asked by the public regularly, and I'm curious to see how others respond.
3
votes
1answer
24 views

What to cite for MSX6 survey?

Here is my current dilemma: I used the data from MSX6 Survey and want to put a citation or some kind of acknowledgment but I can't seem to find any concrete paper or reference text to put in the ...
14
votes
3answers
466 views

What is the probability that a star of a given spectral type will have planets?

There is a lot of new data from the various extrasolar planet projects including NASA's Kepler mission on extra-solar planets. Based on our current data what is the probability that a star of each of ...
17
votes
2answers
5k views

How many stars are in the Milky Way galaxy, and how can we determine this?

I have heard multiple estimates on the quantity of stars within our galaxy, anything from 100 to 400 billion of them. The estimates seem to be increasing for the time being. What are the main methods ...
10
votes
2answers
2k 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 ...
6
votes
2answers
304 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 ...
4
votes
2answers
166 views

Is there a good explanation for the observation of Martian canals?

Martian "canals" have been observed by independent observers after their first description. Now, they are attributed to "optical illusion", but I think that this is not a good choice of word, because ...
8
votes
10answers
179 views

Are there websites or programmes that permit a simulation of the night sky in the past and the future on an ordinary computer?

Are there websites or programs that permit a simulation of the night sky in the past and the future on an ordinary computer? (For the past, I would be content with objects visible to the naked eye.) ...
6
votes
1answer
121 views

How dark does it have to be to see the gegenschein?

I know I've seen zodiacal light, especially at my old club's best dark-site. However, I'm pretty sure I've yet to see the gegenschein. How good does the seeing have to be to be able to see that?
8
votes
1answer
92 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, ...
5
votes
1answer
18 views

What criteria were used to set the “useme” flag in the NOMAD astrometric catalog?

How was the value of the "useme" flag in the NOMAD astrometric catalog set? The readme just describes the field as "Recommended astrometric standard," but says nothing about the basis on which that ...
9
votes
2answers
144 views

What are the prerequisites for considering any other planet to be habitable?

Well, there is a measure of how a planet could be considered like Earth, called Planetary habitability. Based on this measure, what are the prerequisites needed to consider a planet to be a habitable ...
7
votes
6answers
2k 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 ...
23
votes
3answers
3k 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 ...
6
votes
2answers
656 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 ...
29
votes
4answers
643 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 ...
11
votes
2answers
113 views

Who should I contact if I see an unknown object in the sky?

Who should I contact if I see an unknown object in the sky? Should I contact the nearest observatory? Or is there some official place run by, say, NASA or ESA that take in observations in their ...
12
votes
5answers
6k views

Does Earth have a code name?

Everything we discover in the sky get eventually a code name, like NGC 7293, Simeis 147, etc. Does Earth/Moon have a code name too? Or it is just Earth/Moon, etc.?
4
votes
2answers
437 views

Resources and requirements for amateur spectroscopy

If I wanted to move beyond just looking through my eyepieces and taking photographs of astronomical objects, what can I do do move into astronomical spectroscopy? Are there any good resources for ...
8
votes
2answers
977 views

Is there any evidence for the claim that the moon was once part of the Earth?

There is a hypothesis that says a part of the Earth was split away and became the Moon. Is there any scientific evidence for this claim?
4
votes
1answer
1k views

What are the pros and cons of a german equatorial mount vs. a fork mount?

Not much more to add. Why pick one over another?
7
votes
1answer
105 views

What is a backlit CCD sensor, and why might I prefer it to other kinds?

I've heard Astronomers talking about backlit CCD sensors, and talking about how much better they are than other types. What are they, why might I want to get one, and what are the pros/cons of this ...
7
votes
1answer
20 views

What tools do I need to track an orbit of a mystery object?

A while back I was observing Uranus with my 6" dob and a moving object tracked across my field of view. I was at about 90x at the time, and the object was pretty bright but slow moving. I dropped down ...
6
votes
2answers
45 views

Scientific value of timing total lunar occultations

Is there still scientific value in timing and reporting total lunar occultations? Why would I time total lunar occultations (grazing occultations are out of the question)? When I reported ...
15
votes
3answers
5k views

Observing lunar lander and footprints on the moon?

After Apollo 11 first landed on the Moon in 1969, there have been conspiracy theories that this never really happened and that it was all a hoax. In 2010 NASA released photos from its Lunar ...
5
votes
1answer
284 views

A method to estimate the relative magnitude of a star using nearby stars

I remember a method to make a reasonable estimate of the magnitude of a given star X by using two other stars of known magnitude as references. The method used evaluation phrases like "the star X and ...
13
votes
5answers
4k views

Where can I find public domain astronomical pictures?

Where can I find public domain astronomical pictures of nebulae, stars, etc. that can be freely used?
2
votes
2answers
69 views

What objects look best in an O-III filter?

I've heard that an O-III (Oxygen III) filter is great for planetary nebulae. Is this true for all planetary nebulae, or just some or most? What other target types are often improved with an O-III ...
9
votes
3answers
30 views

What are good resources for someone looking to become an amateur astronomer?

What resources would you consider to be essential for an amateur astronomer?