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.

learn more… | top users | synonyms (2)

1
vote
1answer
192 views

What's the amount of deviation of cellestial orbits from perfect ellipses

It's well known that the planets don't orbit the sun in perfect circles and the characteristics of the elliptical orbits which serve as better approximations to their motion have been calculated ...
4
votes
2answers
39 views

How bright will an asteroid be?

In the news, it has been stated that there will be a fairly large asteroid passing fairly close to Earth soon. I've been trying to find a good observation guide, including determining how bright it ...
5
votes
2answers
61 views

Does Mercury have a balmy spot?

From Wikipedia: Although the daylight temperature at the surface of Mercury is generally extremely high, observations strongly suggest that ice exists on Mercury. Does that mean there could be a ...
2
votes
1answer
24 views

What was the most distant supernova spotted by a amateur astronomer until today?

What type of commercial amateur telescope and what method (difference imaging,...) did he use for identifying the supernova?
5
votes
4answers
1k views

Creating a Star Map

I have a set of data on all the stars (well, to a magnitude of 9 or so) with the values of the following properties: magnitude, right ascension and, declination. Now I'd like to create a planar ...
10
votes
1answer
552 views

How to explain the Moon halo phenomenon?

Today, here in Brazil, I have observed (and is still observing) an interesting phenomenon. The Moon is near to a big star in the sky, but this is normal. The interesting part is what's around them. ...
6
votes
1answer
214 views

What is the orbital path of Omega Centauri?

I was under the impression the only objects relatively close to our Milky Way but not yet a part of it were the Sagittarius Dwarf and Large and Small Magellanic Clouds and then much further out, but ...
6
votes
2answers
295 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 ...
3
votes
1answer
570 views

Sky-Watcher Skymax-127 (AZ) 127mm (5") f/1500 SynScan GO-TO Maksutov-Cassegrain Telescope

I have not purchased the above item yet but was wondering whether or not I should? Can I hook this scope up to a monitor or laptop so I can see what my scope is seeing? Is this scope is any good at ...
9
votes
1answer
171 views

Biggest crater in the Solar System

It seems that the biggest crater in the Solar System is Borealis Basin on Mars. The Wikipedia entry and this piece of news say it has been formed by an impact with a body of around 1600 - ...
0
votes
1answer
2k views

Triangulation for Astronomical Distances

How can triangulation be used to calculate the approximate distance to very distant celestial bodies like stars, globular clusters, etc.? And can it be used to measure the distance to a Black Hole? ...
5
votes
3answers
734 views

What is the minimum magnification needed for an instrument to see all the Messier objects?

I know someone that wants to buy a 60cm (1.5 inch) refractor and I thought about recommending what to look at the Messier objects. And I was wondering, can he see all these objects with that refractor ...
7
votes
1answer
2k 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?
4
votes
3answers
527 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)?
3
votes
1answer
148 views

Moons of the planets

What is the phenomena behind gas giants like Jupiter and Saturn having a large number of moons as compared to other planets. Were the present state moons a part of their parent planet long time ago ?
6
votes
1answer
125 views

Why does Omega Centauri have a distinct chemical signature from the rest of the Milky Way?

In answering a question about the orbital path of Omega Centauri, I learned that it has a distinct chemical signature from the rest of the Milky Way. Basically, it is very rich in s-process elements, ...
9
votes
1answer
22 views

Ring height stats?

I'm working on a basic simulation system which will include planets with rings, I want to create dust and asteroids within a 3D ring but I'm struggling to find any stats on the sort of height ranges a ...
6
votes
2answers
2k 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 ...
3
votes
1answer
1k views

How to draw a star chart?

How does one draw a star chart like this? I have: a star database with coordinates (right ascension - RA, declination - DEC), observer coordinates (latitude, longitude) and time of observation. I ...
12
votes
3answers
2k 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 ...
2
votes
2answers
981 views

How can I visualize a gas giant?

From wikipedia Gas giants are commonly said to lack solid surfaces, but it is closer to the truth to say that they lack surfaces altogether since the gases that make them up simply become ...
2
votes
3answers
3k views

What does Orion's Belt look like from the Equator?

I've been struggling with this question all morning, yet I get the feeling the answer is frightfully simple. If Orion appears upside down in the Southern Hemisphere and the right way up in the ...
14
votes
5answers
4k 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 ...
0
votes
0answers
32 views

Expansion of Universe [duplicate]

Possible Duplicate: Why space expansion affects matter? If the Expansion is prevalent, i.e. it is observable and true then shouldn't that result in the expansion of the Milky Way galaxy, ...
1
vote
1answer
204 views

Distance at which a 300m asteroid is visible

Using the best available telescopes, and assuming a typical albedo of 10%, at what distance can a 300m asteroid be seen (well enough to start plotting its course) in 1) visible and 2) infrared ...
2
votes
1answer
332 views

When would the proposed black hole at the centre of Milky Way gulp in our solar system? [duplicate]

I've heard and read that our solar system lies near to the peripheral region of the Galaxy. Then accordingly we would have a greater probability of sustaining to eventual gulping down by the ...
12
votes
2answers
31 views

Why are binary objects so critical to astronomy?

There are a lot of astronomical objects out there to study but binary objects seem to get more attention. Why is this? What makes binary objects (stars, Kuiper Belt Objects, black holes, galaxies, ...
15
votes
6answers
155 views

What to show a beginner [closed]

At my new job, it's soon going to be my turn for doing night/graveyard shifts for a fair amount of weeks. Perfect excuse to buy a decent beginners telescope to replace the 4.5" 15 y/o Meade that ...
1
vote
0answers
231 views

How to find orbital radius of star in a binary system using redshift and orbital period data? [duplicate]

Possible Duplicate: About binary stars and calculating velocity, period and radius of their orbit I am given the non-redshifted wavelength of the EM radiation from one of the stars, the ...
1
vote
2answers
93 views

On constancy of cometary orbits

how are the comets able to keep to a nearly fixed orbital period, though they lose a certain amount of mass during their perihelion?
3
votes
1answer
450 views

How early can scientists detect that a deadly asteroid will hit planet earth?

With the advancements in science and technology, how early can scientists of the world detect that a certain asteroid will hit planet earth and cause damage? Are there any impact avoidance strategies ...
1
vote
2answers
767 views

Could a solar flare cause the Earth's magnetic poles to reverse?

With all the hype of the impending "2012 Mayan doomsday" I was thinking it might be interesting to see what principles of physics prevent the theories of doomsday from occurring. One overarching ...
2
votes
1answer
91 views

Is the environment around an asteroid harsher than in interplanetary space?

In the wikipedia article about NEAR Shoemaker it is mentioned that the craft stopped operating under these conditions: At 7 p.m. EST on February 28, 2001 the last data signals were received from ...
4
votes
2answers
817 views

What's the reason for the seasons?

In the diagram, it shows that the fundamental reason for different seasons is when the northern hemisphere is titled towards the sun there's summer in northern hemisphere and winter in southern ...
1
vote
3answers
178 views

Rocket needed to send 100 gram of mass to outer space? [closed]

What kind of rocket would be needed to send 100 gr of mass to outer space? The mass can be moulded in any shape, but it would need not raise above 40 °C of temperature during the ...
11
votes
2answers
127 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 ...
6
votes
1answer
125 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?
3
votes
2answers
5k views

Glycerol: refractive index & absorption spectra in 0.2-0.4um range

Could anyone suggest where can I find absorption spectra & refractive index of Glycerol? I am specifically interested in UV range, 200-400nm, everything I was able to find out was for standard ...
8
votes
1answer
165 views

Best periods to observe Magellanic Clouds?

When is the best period of the year to observe the LMC and SMC in the Southern hemisphere, so that I can observe them at a reasonable time (e.g. around 10 in the evening?). I am in Sydney.
11
votes
4answers
13k 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?
8
votes
2answers
2k 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?
6
votes
2answers
163 views

How can I judge a globular cluster on the Shapley & Sawyer scale?

Globular clusters were classified by Shapley and Sawyer as being on a scale from 1 to 12 where 1 is very loosely packed central area and 12 is highly packed central area. As a visual astronomer, it ...
10
votes
3answers
299 views

Why is M42 red in the pictures, but green when observed at the eyepiece?

I saw magnificent images of the Orion Nebula (M42) in pictures from Wikipedia, However, when observed with a telescope, the nebula appears green hued, and I can't see any of the characteristic red ...
-1
votes
3answers
575 views

What age to start kids with astronomy [closed]

My son is getting interested in astronomy. I was thinking about getting him a scope when he gets a bit older, he is 4 now. At what age have other people gotten their kids telescopes? (I have a 10" dob ...
9
votes
3answers
34 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?
2
votes
2answers
79 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 ...
5
votes
1answer
340 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 ...
16
votes
3answers
7k 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 ...
7
votes
1answer
29 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 ...
7
votes
1answer
124 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 ...