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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19
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6answers
4k views

Why are the orbits of planets in the Solar System nearly circular?

Except for Mercury, the planets in the Solar System have very small eccentricities. Is this property special to the Solar System? Wikipedia states: Most exoplanets with orbital periods of 20 ...
1
vote
1answer
192 views

Astrophysical Data

I am working on a project that requires some amount of number crunching. I require some basic data about the galaxy M82 and our own Milky Way (particularly luminosities). My advisor is a nut and he ...
2
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0answers
324 views

What is the name of the physical space enveloping all universes? [closed]

Please excuse my question, as i don't come from a physics background, but i was really wondering. Assuming we are in one of numerous universes which all have physical dimensions: What is the name of ...
4
votes
1answer
348 views

Exoplanet surface detail: Limitations on size of space telescope array

How big could an array of space telescopes acting as an interferometer be ? How big would it have to be to resolve exoplanet surface detail the size of Iceland at a distance of 100 light years ?
4
votes
1answer
352 views

Lunar twilight and sixth magnitude stars

Summary: when the Moon is x degrees below the horizon, it interferes with stargazing the same as astronomical twilight would. What is x (as a function of the Moon's phase)? We define civil, ...
30
votes
8answers
22k views

Why CAN we see the new moon at night?

I understand that the Moon's phases are determined by its position in orbit relative to the Sun. (See: Full Story on the Moon). The "shadow" is not cast by the Earth (a common misconception - this is ...
14
votes
6answers
5k views

Why is the mapped universe shaped like an hourglass?

I've watched a video from the American National History Museum entitled The Known Universe. The video shows a continuous animation zooming out from earth to the entire known universe. It claims to ...
11
votes
3answers
485 views

If time standard clocks and any memories about the time standard are destroyed, can we recover the time standard again?

Assume the time standard clocks and any memories about the time standard are destroyed. Can we recover the time standard again exactly? Recovering the time standard again means we can determine the ...
5
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3answers
993 views

How would I calculate celestial body characteristics without a priori knowledge?

Without any a priori knowledge of the mass, speed, distance, and size of local celestial bodies (aside from Earth's size), what can I calculate and how from my "backyard" through observation? Edit: ...
9
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5answers
3k views

What methods can astronomers use to find a black hole?

How can astronomers say, we know there are black holes at the centre of each galaxy? What methods of indirect detection are there to know where and how big a black hole is?
2
votes
7answers
451 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? ...
3
votes
4answers
6k views

Planet orbits: what's the difference between gravity and centripetal force?

My physics teacher says that centripetal force is caused by gravity. I'm not entirely sure how this works? How can force cause another in space (ie where there's nothing). My astronomy teacher says ...
6
votes
2answers
825 views

Calculating the illumination of the moon

I am trying to find a formula that will enable me to calculate the illumination of the moon down to one thousandth of a percent, given that the Gregorian year, month, day, and hour is known. Can ...