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.
7
votes
2answers
439 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 ...
6
votes
3answers
221 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 ...
2
votes
0answers
123 views
Future space-based telescope array
Radio-telescopes (e.g. the Very Large Array (VLA)) can simulate one gigantic dish by using separate smaller dishes.
Q: Could such an array of optical telescopes potentially see an exoplanet at say 20 ...
0
votes
0answers
28 views
How do stars look like from space? [duplicate]
Possible Duplicate:
Optical explanation of images of stars?
What are these rays that appear in photograph of sun?
I thought stars should look round shaped (similar to a sphere, or oblate ...
0
votes
2answers
72 views
Approach of the Andromeda Galaxy
So, it's theorized that Andromeda will collide with the Milky Way some time in the next 3 billion years...
I don't get how galaxies can collide with each other. What is the cause of their movement? ...
1
vote
1answer
138 views
What is the apparent diameter of the sun as seen from earth?
I know this may not be physically accurate.
For my purposes, basically 3D renders, I am assuming the sun rays are parallel rays from an infinitely far lamp. If the sky is clear, what size would that ...
13
votes
3answers
133 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 ...
1
vote
1answer
490 views
How to determine day/night based on latitude, longitude and a date/time?
Is there a simple method of determining, given a UTC date/time, whether it is day or night at a given lat/long coordinate?
I am currently using a formula based on a Sunrise/Sunset Algorithm from the ...
5
votes
2answers
107 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, ...
10
votes
2answers
103 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 ...
5
votes
1answer
37 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. ...
8
votes
1answer
288 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?
2
votes
1answer
57 views
closure phase measurement in astronomy for vlbi technique?
I have read this page on closure phase and could not understand the following:
\begin{align}
\psi_1 & = \phi_1 + e_B - e_C \\
\psi_2 & = \phi_2 - e_B \\
\psi_3 & = \phi_3 - e_C.
...
10
votes
4answers
85 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 ...
3
votes
0answers
126 views
Determine date of birth from “astrological” signs?
Suppose someone tells me what constellation the Sun, Moon, Mercury,
Venus, Mars, Jupiter, and Saturn were in when they were born, and the
information is astronomically accurate (ie, not astrological ...
8
votes
2answers
611 views
Do photons lose energy while travelling through space? Or why are planets closer to the sun warmer?
My train of thought was the following:
The Earth orbiting the Sun is at times 5 million kilometers closer to it than others, but this is almost irrelevant to the seasons.
Instead, the temperature ...
10
votes
2answers
395 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 ...
8
votes
10answers
75 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.)
...
4
votes
2answers
71 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 ...
7
votes
1answer
30 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
615 views
What are the best astronomy blogs and podcasts? [closed]
For someone who likes learning about astronomy what are the blogs and/or podcasts that I should be following?
3
votes
1answer
70 views
Does the spectrum of Sol's emission change as it ages?
A follow-up to my earlier question How would one navigate interstellar space? that just occurred to me; albeit on a different tack.
Sol is probably in a state of continuous flux. The change of state ...
0
votes
0answers
133 views
A book for IOAA [closed]
Hello I am preparing for the International Olympiad on Astronomy and Astrophysics. However my knowledge of constellations and practical astronomy is very poor. I was looking for a book which would ...
9
votes
2answers
62 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
439 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 ...
20
votes
4answers
284 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 ...
8
votes
1answer
169 views
Dumbed-down explanation how scientists know the number of atoms in the universe?
It is often quoted that the number of atoms in the universe is 10$^{70}$ or 10$^{80}$.
How do scientists determine this number?
And how accurate is it (how strong is the supporting evidences for ...
0
votes
1answer
105 views
Do stars appear to move with uniform motion?
The Ancient Greek astronomers had quite an obsession over uniform circular motion; I was wondering if there was a logical reason for this. Did it develop through actual observations of the stars? Do ...
26
votes
4answers
215 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 ...
2
votes
1answer
58 views
Get time from sun Azimuth
I want to know if I can determine the time where the sun's azimuth is at a given value.
In other words, I want a function that takes the sun azimuth along with longitude or time zone and outputs the ...
13
votes
1answer
620 views
Which way do spiral galaxies rotate?
Is it known whether spiral galaxies typically (or exclusively?) rotate with the arms trailing or facing?
Intuitively it feels weird to think of the arms as facing the direction of rotation, but ...
4
votes
1answer
40 views
How fast is the Cosmic Microwave Background Radiation (CMBR) changing?
I know that the Cosmic Microwave Background Radiation (CMBR) is the leftover radiation from the "surface of last scattering".
However, at every instant the surface is changing (at the rate of flow ...
2
votes
3answers
65 views
Name for celestial “Prime Meridian”?
Is there name for the line that goes from celestial pole to pole at RA 0 degrees 0 minutes 0 seconds? On Earth we would call it the Prime Meridian. Is it called the "Celestial Meridian"?
3
votes
1answer
60 views
What could this very dark planet be made of?
I was reading about the planet TrES-2b which is less reflective than charcoal. What could possibly be its composition?
6
votes
1answer
71 views
Does a celestial system exhibit a collective magnetic field?
Sol exhibits a magnetic field, most of the planets in orbit around Sol exhibit a magnetic field - strong and weak both.
Does the solar system as a whole exhibit a magnetic field?
Does the paradigm ...
6
votes
3answers
168 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 ...
2
votes
1answer
146 views
The Moon is slowly moving away from the earth. Does this mean that a total solar eclipse wasn't possible at some point in earth's history?
When the moon was closer to earth, was it still possible to witness a total solar eclipse millions of years ago? Or was the view-able space so small that it was impractical to even witness it?
5
votes
2answers
52 views
Tropical year is 27s/year off from Gregorian year?
http://hpiers.obspm.fr/eop-pc/models/constants.html states the
tropical year is $365.242190402$ days.
The Gregorian calendar's average year is $365.2425$ days (every 4th year
a leap year, except ...
12
votes
1answer
88 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 ...
0
votes
1answer
27 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 ...
0
votes
3answers
76 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 ...
-1
votes
2answers
2k 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 ...
2
votes
0answers
62 views
Elimination of the node
Recently I have been reading a lot of astronomy papers on reductions in models of the solar system. A reoccurring concept is the elimination of the node. However, they never explain what the node is ...
14
votes
2answers
272 views
How deep is the Great Red Spot?
The Great Red Spot (GRS) is a very persistent storm system that's easily visible through a telescope on the surface of Jupiter. But what is the three-dimensional structure of the GRS, and how deep ...
14
votes
2answers
163 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 ...
3
votes
1answer
52 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 ...
6
votes
3answers
39 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 ...
0
votes
0answers
81 views
Mass loss rate of planetary nebulae
The “interacting wind” model of planetary nebulae is based on the idea that the white dwarf phase of stellar evolution is preceded by a red giant phase. A fast wind from the hot white dwarf overtakes ...
2
votes
2answers
184 views
9
votes
1answer
276 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?
