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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4answers
10k 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
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2answers
517 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
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2answers
38 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 ...
0
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1answer
114 views
Does diffraction contribute to the Black Drop effect?
Two reasons are given to explain the black drop effect here, but I think I came up with a third.
Consider a two-dimensional cross section of the situation just after second contact and just before ...
8
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3answers
180 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.
5
votes
1answer
43 views
Is there an Algorithm to find the time when the sun is X degrees above the horizon for a given latitude B at date C
Is there an accurate algorithm / method to determine the precise time of day/night when the sun is X degrees above (or below) the horizon for a given latitude Y at date Z?
Is this the same question ...
2
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1answer
7 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 ...
4
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1answer
350 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 ...
3
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2answers
10 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
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2answers
19 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 ...
5
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1answer
512 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
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3answers
66 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
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1answer
37 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
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1answer
72 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 ...
4
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1answer
66 views
Atmospheric hydrogen in Titan
In 2005, some astrobiologists proposed that methanogenic life on the surface of Titan would consume both hydrogen and acetylene from the atmosphere, causing a downward gradient in the concentrations ...
4
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2answers
164 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 ...
0
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0answers
90 views
Theoretical early-universe cosmology [closed]
I wanted to know what are the cutting edge/recent papers to read w.r.t theoretical early universe cosmology.
I would like to know of recent review papers
I would like to know of areas which use ...
3
votes
1answer
94 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?
5
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3answers
497 views
Is a water world possible, and for how long could it be stable?
I have several questions regarding this topic.
First, could a water world be stable for thousands of years with most of its surface remaining covered in water. What would it take for this to be ...
6
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2answers
86 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 ...
3
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1answer
26 views
What determines a progenitor's fate as a spiral or elliptical?
I was thinking about my answer to Are the inner planets on planar orbits because there was more dust in the inner solar system (early on in planetary accretion)?
- when it occurred to me that maybe I ...
6
votes
3answers
230 views
Tidal force on far side
I have a question about tidal forces on the far side of a body experiencing gravitational attraction from another body.
Let's assume we have two spherical bodies $A$ and $B$ whose centers are $D$ ...
6
votes
1answer
68 views
Detecting dim objects
What are the minimum conditions (switching times, sensitivity ...) for a camera to detect dim objects, e.g. Oort cloud or Kuiper belt objects, passing by in front of a star in the background?
I've ...
6
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1answer
65 views
Is the Apophis asteroid a concern?
I was watching the TED lecture How to defend Earth from asteroids , and the speaker Phil Plait spoke of the possibility of this asteroid hitting Earth. He also said something about a Mayan legend. He ...
5
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1answer
52 views
Shadow of a Jovian moon over the Great Red Spot
Where can I find pictures of the shadow of any of the Jovian moons partially covering the Great Red Spot?
A series of such pictures over time would even be better. The idea is to learn more about the ...
1
vote
1answer
702 views
Why don't we see solar and lunar eclipses often? [duplicate]
Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Moon at the night and as far as I know if this happens during the day, you'll get to see a solar ...
1
vote
1answer
121 views
How to calculate the amount of night time during a flight?
I have been asked to find a way to calculate the amount of time that a flight takes during night time.
So far, I have the departure latitude and longitude and the time of takeoff, the arrival ...
3
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0answers
73 views
Parallax Cloud Displacement - Angular Distance from Geostationary Satellite
When observing clouds from a geostationary satellite, they appear displaced because of the parallax effect. The satellite looks at the clouds "at an angle" and it projects them on a point of the earth ...
3
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2answers
44 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 ...
1
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1answer
301 views
RA/dec to Alt/Az program or method
I've been looking for a program to convert from RA/dec into Alt/Az; having used a couple of online versions I haven't seemed to find one yet that works reliably. I've tried to do it myself and half ...
21
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9answers
4k views
Can Jupiter be ignited?
Our solar system itself contains two candidate "Earths"
One is Jupiter's moon Europa and another is Saturn's moon Titan. Both of them have the problem of having at low temperature as Sun's heat ...
6
votes
1answer
123 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 ...
0
votes
2answers
48 views
Study of exoplanets reaching saturation point [closed]
In recent exoplanet meeting The Next 40 Years of Exoplanets, it was mentioned a few times that the field/topic is becoming saturated.
In what ways is it becoming saturated, and can you see the effect ...
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vote
2answers
433 views
What is meant by positive and negative gravity/energy/spactimecurvature?
I have recently come across some cosmological assertions (based on empirical data) about the universe being self contained in the sense that it is entirely capable of coming into existence from a ...
6
votes
1answer
447 views
How do we know the masses of single stars?
I have recently read that we can only know the masses of stars in binary systems, because we use Kepler's third law to indirectly measure the mass. However, it is not hard to find measurements for the ...
12
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1answer
162 views
Impact location that created the moon
I was reading an article today about the 1000th orbit of the Lunar Reconnaissance Orbiter, and as many of you know NASA created an animation that simulates the history of the moon. It is speculated ...
3
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2answers
48 views
Figuring out which moons of Jupiter I saw through my telescope
Three days ago (Sunday 11st March) in London using my new telescope I was able to see Jupiter and three of its moons. It was very clear and easy to spot. How can I determine the names of the moons I ...
4
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4answers
260 views
Are galactic stars spiraling inwards?
Are the stars in our galaxy spiraling inwards towards the center, or are they in a permanent orbit?
And if we are heading towards the center then what is the rate of this process?
I started ...
7
votes
1answer
309 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?
6
votes
2answers
36 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 ...
6
votes
1answer
110 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 ...
4
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1answer
394 views
Convert ECI coordinates to latitude/longitude?
I have been given output in (what I believe to be) ECI format (from OrbitTools):
...
12
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3answers
51 views
Which is the strongest meteor shower expected in the next years in the Northern hemisphere?
Which is the strongest meteor shower expected in the next years in the Northern hemisphere?
Is it possible to give good predictions for this?
1
vote
1answer
131 views
When calculating the local apparent sidereal time, which time scale should I use?
UT1, UTC, TAI, TDB, or what?
I need to determine the time difference between a given observation and the epoch from which certain constants apply. I typically work with the J2000.0 epoch. This is to ...
4
votes
2answers
129 views
Need help buying binoculars online for astronomy (10x50)
After reading much online I've decided to by a 10x50 porro prism Binoculars. The one I have in mind http://www.letsbuy.com/celestron-upclose-10x50-p-34652 has BK7 prisms. The one I would like to buy ...
1
vote
2answers
93 views
What does “equinox of date used” mean?
The documentation for an API I often use for quick astronomical modeling and figure drawing says
Positions are given in FK5 heliocentric coordinates in the equinox of the date used.
What does ...
6
votes
3answers
252 views
How accurately is the moment of perihelion of Earth known, and how is it measured?
Earth's perihelion passed about nine hours ago. How accurately do we know the moment of closest approach of the Earth to the center of the sun? How do we make this measurement?
2
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3answers
106 views
How is a star's parent galaxy recognized?
A star is probably visible/detected by it's radiation. But that star may or may not belong to our own galaxy ... yet news reports speak of detecting a star/nova in a distant galaxy.
How does one ...
2
votes
3answers
704 views
Is it possible for the planets to align?
We've all heard the statement that on the 21st of December, the planets in the solar system will "align" from the point of view of the Earth. I assume this means that they would all be in the same ...
3
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1answer
159 views
How did pre-Copernican astronomers accurately predict planetary position?
Copernican elements (circular orbital elements) are not very accurate. But Copernicus simplified our understanding a great deal by placing the Sun at the center of the system. Im astonished by the ...
