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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8answers
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Would it matter if the Earth rotated clockwise?
In the Futurama episode "That Darn Katz!" they save the world by rotating the Earth backwards saying it shouldn't matter (which direction Earth rotates). If Earth rotated clockwise and remained in ...
26
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4answers
217 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 ...
22
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4answers
2k views
Why is a new moon not the same as a solar eclipse?
Forgive the elementary nature of this question:
Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse ...
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 ...
20
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4answers
288 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 ...
18
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5answers
135 views
Given a photo of the Moon, taken from Earth, is it possible to calculate the position of the photographer's site?
Given a photo of the Moon, taken from Earth, is it possible to calculate the position (Earth longitude and latitude) of the photographer's site?
I am thinking about photos taken with a normal camera ...
17
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7answers
8k 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 ...
17
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3answers
429 views
Direct observations of a black hole?
I'm not very knowledgeable about physics generally, but know that nothing can escape a black hole's gravitational pull, not even light (making them nearly invisible?).
My question is: What has been ...
17
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2answers
790 views
Can a planet have a larger diameter than Jupiter?
I have heard it said that if mass were added to Jupiter, then only its mass and density would increase but the diameter would stay about the same. Is this the case for Jupiter or some property of ...
16
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5answers
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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 ...
16
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2answers
207 views
How would the night sky appear at the edge of the galaxy?
In Isaac Asimov's Foundation Series, there is a planet named Terminus which is believed to be the planet farthest from the galactic center.
There are almost no visible stars in its sky, only the ...
15
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6answers
68 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 ...
15
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5answers
735 views
What do the colors in false color images represent?
Every kid who first looks into a telescope is shocked to see that everything's black and white. The pretty colors, like those in this picture of the Sleeping Beauty Galaxy (M64), are missing:
The ...
15
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3answers
452 views
Does the Moon's core still contain significant heat?
On earth, using earth-sheltering techniques can significantly reduce the temperature fluctuations on a structure. Would the same statement be true as well on the Moon? Does the Moon's core still ...
15
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2answers
65 views
Recommend good book(s) about the “scientific method” as it relates to astronomy/astrophysics?
I am interested in astronomy/astrophysics, but I am not science major (I am a computer science graduate). Facts and results of the field are presented to the public without showing how these ...
14
votes
2answers
165 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 ...
14
votes
2answers
274 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
1answer
115 views
What happens to the electron companions of cosmic ray protons?
If primary cosmic rays are made mostly of protons, where are the electrons lost, and does this mean that the Earth is positively charged?
Does the sun eject protons and electrons in equal number?
14
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1answer
232 views
Why don't any of the gas giants have moons of Earth's mass (or greater) that orbit them? Is this generalizable to exoplanet gas giants?
Now, we know that the composition of the outer planets tend to contain a much higher ratio of ice over rock. [1] So the lack of Earth-like moons around the outer planets that this could be an artifact ...
13
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5answers
50 views
How do you respond to questions like “Have you ever observed a UFO?” [closed]
This is a question that astronomers get asked by the public regularly, and I'm curious to see how others respond.
13
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4answers
139 views
Why don't we have a better telescope than the Hubble Space Telescope?
The Hubble Space Telescope (HST) was launched in 1990, more than 20 years ago, but I know that it was supposed to be launched in 1986, 24 years ago. Since it only took 66 years from the fist plane to ...
13
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5answers
788 views
Telescope for 6 year old and dad new to astronomy
What's a good telescope for my 6 year old? We're both brand new to telescopes in general, but love space, stars, planets, cosmology, etc. Happy to spend up to $200 to start. Maybe more for a good ...
13
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3answers
1k views
Do all the individual stars that we can see in the night sky belong to Milky Way?
I was wondering if all the stars that we can see with the unaided eye as distinct point sources are from our own galaxy?
In other words, can we see stars from the Andromeda Galaxy or other galaxies ...
13
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4answers
131 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 ...
13
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3answers
134 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 ...
13
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3answers
111 views
How are newly discovered objects (stars, planets, galaxies…) named?
When a new astronomical object (star, planet, galaxy, comet, etc.) is discovered, what is the official procedure to name it? Who decides about the name of it? Can they be changed in time?
Extra ...
13
votes
2answers
267 views
Why aren't gas planets and stars fuzzy?
The edge of Jupiter looks very sharp.
Even more bothersome, the edge of the sun looks sharp, aside from kind of a soup of particles floating above it.
The sun's surface has an incredibly low ...
13
votes
1answer
382 views
What percentage of the sky is occluded by stars?
If you drew rays from the center of the earth out to infinity at every angle, what percentage of them would intersect a star?
Extra details:
Assume the rays are mathematical rays, or that they ...
13
votes
1answer
636 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 ...
12
votes
9answers
169 views
In astronomy what phenomena have theory predicted before observations?
As far as I know, astronomy is generally an observational science. We see something and then try to explain why it is happening. The one exception that I know of is black holes: first it was thought ...
12
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4answers
3k views
How do astronomers measure the distance to a star or other celestial object?
How do scientists measure the distance between objects in space? For example, Alpha Centauri is 4.3 light years away.
12
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2answers
88 views
What is the most distant object from the Earth that a spacecraft has visited to date?
What is the most distant object from the earth that a spacecraft visited has visited so far? What was the mission and when did it happen?
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 ...
12
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3answers
697 views
Observing lunar lander and footprints on the moon?
After Apollo 11 first landed on the Moon in 1969, there have been conspiracy theories that this never really happened and that it was all a hoax. In 2010 NASA released photos from its Lunar ...
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?
12
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1answer
2k views
How many stars are in the Milky Way galaxy, and how can we determine this?
I have heard multiple estimates on the quantity of stars within our galaxy, anything from 100 to 400 billion of them. The estimates seem to be increasing for the time being. What are the main methods ...
12
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2answers
279 views
What if our Sun were located in the middle of a globular cluster?
Say you took our current solar system and relocated it deep in the heart of a globular cluster such as Omega Centauri. What would the night sky look like? Would the starshine of nearby stars be enough ...
12
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2answers
21 views
Why are binary objects so critical to astronomy?
There are a lot of astronomical objects out there to study but binary objects seem to get more attention. Why is this? What makes binary objects (stars, Kuiper Belt Objects, black holes, galaxies, ...
12
votes
1answer
89 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 ...
11
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6answers
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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
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4answers
1k views
Does Earth have a code name?
Everything we discover in the sky get eventually a code name, like NGC 7293, Simeis 147, etc.
Does Earth/Moon have a code name too? Or it is just Earth/Moon, etc.?
11
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2answers
156 views
What is the largest observed celestial body?
I'm not referring to phenomena such as galaxies or clusters but rather, what is the largest discrete celestial body that has been observed in the universe?
11
votes
2answers
68 views
Who should I contact if I see an unknown object in the sky?
Who should I contact if I see an unknown object in the sky?
Should I contact the nearest observatory? Or is there some official place run by, say, NASA or ESA that take in observations in their ...
11
votes
1answer
138 views
Relationship between Mars and Earth rotation
Is it by pure random chance that Mars and the Earth have nearly the same day duration (Mars day is barely 40 minutes longer, which is just 3% difference), or there is some causal relationship between ...
11
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0answers
288 views
Strange things about new moon [duplicate]
I have some strange and infantile questions about new moon. I want to know how is it possible that the Moon is not visible at night and also at day it is not Sun eclipse?
I will explain the problem in ...
10
votes
5answers
2k views
What is an asterism compared to a constellation?
I'm doing an astronomy exam tomorrow and in the practice paper it asks for the difference between constellation and asterism. It seems asterism is a group of recognizable stars; however I thought that ...
10
votes
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?
10
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5answers
1k views
Where can I find public domain astronomical pictures?
Where can I find public domain astronomical pictures of nebulae, stars, etc. that can be freely used?
10
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5answers
558 views
Why cant one see tidal effects in a glass of water?
Why cant one see the tidal effect in a glass of water like in an ocean?
10
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3answers
90 views
Why is M42 red in the pictures, but green when observed at the eyepiece?
I saw magnificent images of the Orion Nebula (M42) in pictures from Wikipedia,
However, when observed with a telescope, the nebula appears green hued, and I can't see any of the characteristic red ...
