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.
4
votes
2answers
184 views
Novice interested in buying a used telescope. What questions should I ask? [closed]
I've noticed quite a few decent telescopes for great prices on craigslist, but I am a complete novice and don't know the first thing about them. I thought I would be able to pick up what I needed from ...
4
votes
2answers
79 views
How is the shape of the universe measured by scientists?
I would like to learn how scientists go about measuring the large-scale curvature of the universe to determine if the universe is closed 'i.e. spherical', flat, or open 'i.e. saddle shaped'.
My ...
3
votes
3answers
2k views
How fast will the sun become a red giant?
I've read many accounts of our sun's distant fate, but what I've never heard is on what time scale these events occur.
For instance, when the sun runs out of hydrogen, I presume it doesn't just WHAM! ...
3
votes
3answers
953 views
Why do stars have absorption spectra?
Absorption spectra are a result of light of a certain wavelength exciting an atom from a lower energy level to a higher one and at the same time being absorbed. However, the atom should eventually go ...
2
votes
1answer
177 views
Where to find the current positions and velocities of the planets?
I've written a program which simulates the motions of planets and other bodies. I'd like to run it on our own solar system, but to do so I need to know the current positions (preferably in ...
2
votes
1answer
57 views
Are the inner planets on planar orbits because there was more dust in the inner solar system (early on in planetary accretion)?
Question inspired by a question thread here.
So when there's lots of dust in a galaxy, the galaxy tends to collapse into a spiral galaxy (to maintain angular momentum and to minimize gravitational ...
2
votes
1answer
260 views
At what temperature does water become a liquid on Mars? On the asteroids? And in a vacuum?
I know that I can just read off the phase diagram for water (for the surface atmospheric pressure on each object). But could there possibly be some nuances that someone might miss just from viewing ...
2
votes
1answer
247 views
What happend with the light from all the galaxies visibles from an earth telescope?
Supposing it's possible to see some distant galaxies with an earth telescope, then, at the tip of the telescope lens there are photons comming from the distant galaxy...
So, if I extend my hand in a ...
2
votes
7answers
388 views
Can astronomers directly detect black holes?
Are there any methods of direct detection for black holes?
I'm not referring to gravitational lensing, or measuring the orbits of a star in a binary pair.
Is there any way of directly 'seeing' them? ...
1
vote
1answer
708 views
What is the relationship between mass, speed and distance of a planet orbiting the sun?
After reading this fascinating story about a new exoplanet, I was wondering about how mass, speed and distance determine a circular orbit of a planet around a star.
Given the mass of the sun and ...
1
vote
1answer
690 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
491 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 ...
0
votes
0answers
115 views
To measure the distance to a star using spectroscopic parallax which two do you need to know? [closed]
To measure the distance to a star using spectroscopic parallax which two do you need to know?
A) Spectral type
B) Parallax angle
C) Visual or apparent magnitude
D) Mass
0
votes
1answer
124 views
Gyrochronology, the formula is empirical ?
The formula used in Gyrochronology that relates a star's Period of Rotation-Mass-Age is empirical?
This news How to Learn a Star’s True Age
"“A star’s rotation slows down
steadily with time, ...
