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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20
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2answers
629 views

Why don't stars in globular clusters all orbit in the same plane?

Globular clusters like Omega Centauri certainly don't seem to be very coplanar at all. In other words, why doesn't the explanation at Why are our planets in the solar system all on the same disc/...
0
votes
1answer
47 views

Where to get hard historical and trend data related to reentry of satellites like UARS [closed]

NASA is providing very brief updates on the reentry of the UARS satellite. They also published an extensive study of the Re-entry and risk assessment for the NASA Upper Atmosphere Research Satellite (...
5
votes
3answers
775 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 ...
0
votes
3answers
245 views

Why is it hard to write a computer program to detect patterns which planethunters is asking us to figure out? [closed]

I recently came across this site http://www.planethunters.org. It shows brightness observed for a star vs time. It asks questions like if star is exhibiting variable or fixed pattern. Later it asks if ...
8
votes
2answers
613 views

“Reverse engineering” of a horoscope?

I'll start with a disclaimer -- this is not a question about astrology itself, I'm neither trying to refute nor to defend astrology. I'm interested in purely technical things, which are mostly ...
4
votes
3answers
262 views

Fall/Winter Viewing

I live in Seattle and am thinking of purchasing a telescope. Is fall/winter a decent time of year for viewing (aside from summer)? Are there any major viewings/events during that this of year? I know ...
-1
votes
2answers
5k views

Celestron NexStar 6 SE vs. Orion XT8 [closed]

I'm interested in purchasing a new telescope and have narrowed it down to the NexStar 6 SE vs. the Orion XT8. I'd like to be able to get into astrophotography and read that having the Go-To (auto-...
3
votes
3answers
148 views

Photographs of galaxies many light years far from the Earth

Using ground-based telescopes or the Hubble Space Telescope, astronomers take photographs of galaxies which are many light years from the Earth. Does it mean those photographs are as old as the ...
8
votes
3answers
1k views

Are planetary orbits measured from the Sun's surface or centre?

I would imagine planetary orbits are measured from the Sun's centre and not its surface. Is that true? I can't find anywhere that actually states this.
0
votes
3answers
66 views

Why can't Jupiter be seen over Thanksgiving break?

As of these past few days, Jupiter can be seen in the sky, correct? Around Thanksgiving, why can't it be seen?
2
votes
2answers
56 views

What physical interactions actually make single stars leave their binary companions at formation?

From an interesting ScienceDaily article, I read this Before the groups of stars disperse, binary stars move through their birth sites and the group studied how they interact with other stars ...
0
votes
1answer
277 views

Is water necessary for forming the sedimentary rocks found on Mars' surface?

So, I've just been reading a recent ScienceDaily article, and came across this interesting quote "Clays form in more neutral, less acidic conditions than the sulfate-rich sandstones we've been ...
11
votes
1answer
2k views

How vacuous is intergalactic space?

You often hear intergalactic space is an example for a very good vacuum. But how vacuos is space between galaxy clusters and inside a huge void structure? Are there papers quoting a measurement/...
14
votes
2answers
721 views

What percent of planets are in the position that they could be viewed edge-on from Earth? (and thus able to undergo transits)

Star number 12644769 from the Kepler Input Catalog was identified as an eclipsing binary with a 41-day period, from the detection of its mutual eclipses (9). Eclipses occur because the orbital ...
6
votes
1answer
282 views

Axial Tilt and precession rate of exoplanets

The Earth's axis is 23.5 degrees away from othogonality to the ecliptic, and it takes about 26 000 years for it to precess fully. I have neither an intuitive sense nor the formula for precession ...
3
votes
1answer
82 views

Phases of the moon video

I am an educator, and I am looking for a specific video. In the video, they ask some middle school students and some college graduates about why the moon has phases. Most of the students in both the ...
3
votes
2answers
100 views

Computing period, semi-major axis of binary

I have mass, $g$, and luminosity of each of the stars in a binary system, extracted from a model. I calculated the individual radii from $g$ and the mass. I am trying to compute $a$, but I seem to be ...
5
votes
3answers
98 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 ...
21
votes
3answers
15k views

How long does it take to travel 36 light years with tolerable acceleration and deceleration?

The recent discovery of HD85512b only 36 light years from Earth has promising attributes to harbor life. Assuming we want to travel there, we cannot instantaneously jump to light speed, (StarTrek ...
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 (...
3
votes
3answers
280 views

On what planar regions are the Earth, Moon.. for that matter, all astronomical bodies, placed in the Universe?

When we are on Earth, we look UP in the Sky to see the Moon. How do we have to look at Earth from Moon.. Is it the way ? If so, how are these bodies actually placed in the space? Are all astronomical ...
11
votes
2answers
1k views

If the Earth didn't rotate, how would a Foucault pendulum work?

How does the Foucault pendulum work exactly, and would it work at all, if the Earth didn't rotate?
17
votes
5answers
36k views

Can the “Milky Way” galaxy be seen by the naked eye in a clear sky?

Is this photo "real"? Are the stars not super-imposed in the image?
2
votes
2answers
3k views

Formula for Rotation curves of Galaxies

To ask a more specific one for the rotation curves of elliptical galaxies, and hope from there to later understand the dynamics of spiral galaxies. Treating the galaxy as an isothermal ...
3
votes
2answers
70 views

Particular targets of high angular resolution infrared telescopes

I work in the field of infrared interferometry, specifically instrumentation. As such, I need to be aware of the science goals of such an instrument. Is there a quick list of important and ...
6
votes
2answers
2k views

What are the differences in using an eyepiece with a barlow instead of a shorter eyepiece?

I intend to start making visual observations, and I want to know more about the difference between using barlow lenses and one or two eyepieces and using a complete kit of eyepieces, both for ...
15
votes
6answers
159 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 doesn'...
3
votes
1answer
82 views

Assuming an observer is 50 light years away, in the plane of the solar system and observing earth, what is the light flux of earth he would see?

As in, from what the planet emits and re-radiates out into space (this is going to be important if we are to image any Earth-like planet)
5
votes
2answers
4k views

How do you measure distance to stars within the galaxy?

I know that for close by stars (<50 LY) we can use the parallax effect. And for distant galaxies we use red-shift (& hubble's constant). So how do we measure how far is a star lets say 50,000 ...
6
votes
1answer
133 views

What conditions should an asteroid or comet impact need to meet in order to start an impact winter?

Is there a way to calculate if an impact from a given asteroid (say 5 miles in diameter, solid rock to which we know the mass) would start an impact winter? If yes, I would like to see a real example ...
4
votes
3answers
70 views

Are our telescopes capable of taking actual images of brown dwarfs?

One nice result from NASA's WISE infrared survey of the sky is the discovery of particularly cool (as in 'not very warm') stars, now called 'Y dwarfs'. This was reported, for example, in NASA's ...
2
votes
1answer
13 views

What is the current evaluation of a sky map application for mobile devices?

Which sky map application for mobile devices have the best "feature satisfaction"-to-investment ratio? I would like to have a comparison between "sky map" applications for mobile devices and it ...
6
votes
2answers
269 views

How can Y-dwarf stars have such a low temperature?

A recent article from NASA said they found some stars with temperatures "as cool as the human body." How is this possible? Does fusion still occur in these stars?
14
votes
4answers
547 views

How far would you need to displace your eyes to get meaningful depth perception of the stars?

The question follows from xkcd cartoon "Depth Perception (941)". I've isolated the frames that describe the concept here. In words, one could theoretically point two cameras at the sky, and ...
5
votes
1answer
1k views

How does the view of night sky change as the Sun orbits around the Milky Way?

I know that the Sun and hence the Solar System orbits around the galactic center of the Milky Way. Does this rotation cause any visible change in the night sky? I know that human life span is ...
2
votes
6answers
80 views

Amateur Stargazing (30 degrees N)

When I look at the sky I easily recognize Orion, The Big Dipper, and the North Star (in relation to the Big Dipper). Besides these (and the moon^^), what easily identifiable (unaided eye) astronomical ...
4
votes
4answers
3k 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?
3
votes
2answers
28 views

For resolving different objects, are there any alternative coefficients to the one used in the Rayleigh criterion? (which is 1.22)

http://en.wikipedia.org/wiki/Angular_resolution#Explanation It's the point where you can't distinguish between the maxima and the first minima. But could there be cases where you have a more ...
3
votes
2answers
153 views

Is angular resolution important when we want the spectra of an Earth-like exoplanet?

Right now, our resolution + light gathering power are still far too low to take direct images of exoplanets, so we're limited to subtracting the planet spectra from the parent star spectra when the ...
6
votes
1answer
3k views

Most accurate ways to find the average distance between stars in Milky way galaxy

I've already posted here on quora. But, I'm not totally sure if it's the most reasonable method. Would anyone care to elaborate on how to find the average distance between stars in a given galaxy (...
7
votes
3answers
5k views

What is the irregularity in Uranus' orbit that is caused by Neptune?

I carefully read the Wikipedia article Discovery of Neptune, and I don't get what the irregularity of Uranus orbit was that lead to the discovery of Neptune. Years ago, I watched some educational film ...
7
votes
3answers
133 views

Are there any Earth-Meteorites on Earth?

A follow-on from this question, if meteorites can come from Mars, it seems they could have come from Earth and ended up back here (though I'm guessing that to be less likely). Do we have any evidence ...
2
votes
1answer
177 views

Do red galaxies have red star-lit skies?

I noticed when looking at some deep space pictures, like the Sombrero Galaxy (M104) or the Hubble Deep Field (HDF), I see galaxies of various colors. Does that mean, for instance, than any inhabitant ...
4
votes
1answer
103 views

What is the format for “local catalog” files used by JSkyCat?

I am trying to use JSkyCat to mark a set of coordinates on a FITS image, and have found the dialog for choosing a catalog file to load. However, I am having trouble finding any documentation on what ...
5
votes
6answers
628 views

Are there free data available online from cosmology (or astrophysics) experiments that anyone can analyse?

One can understand a subject better in physics by trying to solve as many problems as one can from a textbook say. When it comes to experimental physics and data analysis, no book on experimental (...
6
votes
2answers
2k views

Are meteorites igneous, sedimentary or metamorphic rocks?

Are meteorites igneous, sedimentary or metamorphic rocks? Or do we need a new method of rock classification for them?
4
votes
1answer
152 views

Does the Earth help stabilize changes in the moon's obliquity as well?

We know that the moon helps stabilize changes in Earth's obliquity. But what about Earth and the moon? Are some of the obliquity-stabilizing effects (of the moon on the Earth) communicated through ...
3
votes
1answer
235 views

How do the day/night temperature variations of moons compare to those of their planets?

Does the planet's eclipse have a significant impact on the flux of light hitting the moon? Does tidal locking have any effect on the day-night difference of the planet?
13
votes
5answers
2k views

Anti-Matter Black Holes

Assuming for a second that there were a pocket of anti matter somewhere sufficiently large to form all the type of object we can see forming from normal matter - then one of these objects would be a ...