Questions regarding systems of large numbers of stars held together by gravity.

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15
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2answers
338 views

Why is our solar system “tipped” about 63° with respect to the plane of our galaxy?

Our own solar system is "tipped" by about 63 degrees with respect to the plane of the galaxy. Has it ever been researched or is there any scientific theory which could explain the reason why our solar ...
14
votes
1answer
336 views

Milky Way Galaxy from Earth

I've seen a lot of beautiful pictures of the Milky Way from Earth such as this: ...but I can't understand what the cloudy ribbon at the bottom the horizon is. Is it a super-large nebula? Or is it ...
12
votes
2answers
1k views

How many planetary systems exist in our galaxy?

For many years scientists have studied our own solar system and modern technology allows them to look deeper and deeper into space. Knowing the Sun is only one of a few billion stars in the Milky Way ...
11
votes
1answer
147 views

Our galaxy, the Milky Way, forms part of a galaxy group called The Local Group. What are the parameters that dictate what a galaxy group is?

Are there different classifications or just the one? How does our galaxy group compare with others?
10
votes
5answers
3k views

What will happen to life on Earth when Andromeda and Milky Way galaxies collide?

It is said that, Andromeda and Milky way galaxies are coming close to each other with the speed of approx $400000 \ km/hours$. They will be together in the next $4 \ billion years$. What will ...
10
votes
1answer
217 views

Explaining Dark Matter and Dark Energy to layman

With my little knowledge, I know this: Dark Matter The center of a galaxy controls/attracts its objects (stars, planets, comets etc.) towards itself because of gravity. But the mass of the center of ...
9
votes
2answers
120 views

How many galaxies have been discovered?

I know Andromeda is our nearest galaxy. But how many known galaxies have been discovered and what are they?
8
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2answers
75 views

What is the evidence that galaxies rotate?

Do all galaxies rotate? If so, do they rotate in the same direction? What observations have been made of galaxy rotation?
8
votes
1answer
84 views

How do we calculate the escape velocity of galaxies?

How do we calculate the escape velocity of galaxies? Do we have to know the total mass? What is the escape velocity for Milky Way?
7
votes
1answer
60 views

How fast do we travel through space?

Could someone give the rough estimates of speeds of our travel through space? I can easily find the two nearby ones: Earth's own rotation - depending on latitude, up to 40,075 km/24h = 463 m/s ...
7
votes
2answers
335 views

How long until we cannot see any stars from other galaxies?

Since all the galaxies are moving further away from each other at a faster and faster rate, eventually we won't be able to see stars from other galaxies. How long until we can't see stars from other ...
7
votes
1answer
87 views

How do we know Milky Way is a 'barred' spiral galaxy?

In reference to the question, "How can we tell that the milky way is a spiral galaxy?" The answers there clearly sum up the question asked. But Milky Way is not just a spiral galaxy. It is further ...
7
votes
1answer
117 views

Where is Voyager 1 (or 2) going? In which direction?

Knowing it has exited the solar system, is it traveling in the direction of the center of the galaxy, away from it, orbiting it, or maybe even going perpendicular from the disk-shaped galaxy?
7
votes
2answers
106 views

How are Galaxy Super Clusters Generated

I have seen pictures of clusters of galaxies, usually used in regards to theories of dark matter and galaxy formations. One of the most famous ones has the perceived shape of a stick-figure. If I am ...
7
votes
2answers
134 views

How often does Earth cross the galaxy regions with higher supernovae activity?

According to Summa Technologiae, a book by a Polish author Stanisław Lem that based his science fiction novels on scientific research of the era, the Earth crossed in the moment of forming of life the ...
7
votes
2answers
156 views

Are there a lot of collisions between stars in the core of the galaxy?

I'm reading on Wikipedia about Halo Stars that orbit the center of the galaxy at a high inclination away from the plane of the Milky Way. It seems that at some point, these stars must dive back into ...
7
votes
1answer
70 views

Have we observed any rogue/wandering stars?

Do we know (have we observed and cataloged) any rogue star, being not part of galaxy, but drifting somewhere in inter-galactic space? I know that determining if a star is a part of galaxy or not is a ...
7
votes
0answers
88 views

Dark Flow: statistical limits on existence

Dark Flow has been thrown around as a term a lot lately, especially with the latest Planck results. New Scientist reported last year that it was now statistically improbable, but the paper by Atrio ...
6
votes
2answers
400 views

Was the Milky Way ever a quasar?

Is there any evidence that the Milky Way could have been a quasar in it's early history? Is it thought that most galaxies come from quasars?
6
votes
1answer
295 views

How far is the Earth/Sun above/below the galactic plane, and is it heading toward/away from it?

How far is the Earth/Sun above/below the galactic plane, and is it heading toward/away from it? We know the Sun is orbiting the galactic center every 225 million years. But how far are we from the ...
6
votes
1answer
70 views

Supermassive black holes at the center of galaxies

The fact is, many, if not most large galaxies have a supermassive black hole at their center. My question is why? Is it because when these galaxies were first formed supermassive black holes were ...
6
votes
1answer
103 views

Do stars of a galaxy change their positions relatively to each other?

Complete astronomy noob over here who would be happy if he get a simple answer (and who is also aware that this may be not possible)... I've learned from a tv documentary that the stars at the edge ...
5
votes
4answers
192 views

Do solar systems have to evolve in a galaxy?

Is it possible for a solar system like ours to exist and evolve apart from all other star systems and galaxies. Sort of like a stand alone solar system or rogue solar system for lack of a better name. ...
5
votes
2answers
63 views

Are Gamma Ray Bursts of galactic or extragalactic origin?

I read about the 1995 Lamb-Paczynski debate on whether GRBs are galactic or extragalactic in origin. With our current experimental evidence, have we found whether GRBs are galactic or extragalactic?
5
votes
1answer
79 views

Why are galaxies disk shaped?

I always see galaxies in "disk" shape in pictures. It is like, there is a rotational movement on a plane and the system is balanced by the pulling-in gravitational force which prevents the stars to ...
5
votes
1answer
96 views

Computing the Sérsic profile of a galaxy from jpg images

I am trying to calculate the Sérsic profile of various galaxies from the SDSS based on the images provided by the galaxy zoo site. I am doing this as part of a kaggle competition on using machine ...
5
votes
1answer
80 views

How do scientists know there are about 300 billion stars in a galaxy and there are about 100 billion galaxies?

Just to think about this is mind boggling. But how do scientist get these numbers? What technology/system/theory do they they use?
5
votes
1answer
518 views

How many stars and galaxies can be seen naked eye?

How many of the luminous dots that we see naked are galaxies and not stars from our galaxy? I immagine that the majority of the luminous points that we see naked eye during the night, are actually ...
4
votes
2answers
138 views

How can we predict a Big Crunch when all galaxies are moving further apart?

I've read that the further away a Galaxy is from us the faster it moves away. By this logic how can scientists predict that there will eventually be a big crunch when every piece of matter is ...
4
votes
3answers
150 views

Is there a fundamental difference between a small galaxy, and a large star cluster?

For instance, If a large globular cluster were somehow ejected from its galaxy, and was observed by astronomers, would they call it a galaxy, or would there be characteristics of the star cluster that ...
4
votes
1answer
85 views

What do we know about the lifecycle of the Milky Way (or any other spiral galaxy)?

I know that the Milky Way will collide with Andromeda in the distant future but based on what we know so far there is a supermassive black hole in the center of each galaxy and thus the Milky Way will ...
3
votes
1answer
34 views

Active Galactic Nuclei - categorisation on the basis of observer?

As we know AGNs are considered to be one of the most luminous objects to be found in the cosmos.Based on the observer, for instance on Earth, we categorize them on the basis of the angle between the ...
3
votes
2answers
32 views

what is the highest throughput astronomy project in pixels?

I was having a discussing about big scientific projects with colleagues, and I postulated that astronomy is still one of the scientific fields with biggest projects per amount of data dealt with, ...
3
votes
1answer
59 views

Which galaxy is receding from the Milky the fastest? What is known of the mechanism behind its recession?

Galaxies are always in motion relative to the Milky Way, my question is, which galaxy is receding the fastest from our viewpoint? What is the theorised mechanism that causes this?
3
votes
2answers
66 views

Metallicity of Celestial Objects: Why “Metal = Non-metal”?

Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium. Note: The other elements may or may not be actual ...
3
votes
1answer
64 views

Apogalacticon and Perigalacticon

What is the length of the apogalacticon and perigalacticon of the Sun and Milky Way? The general terms seem to be apoapsis and periapsis. My greatest efforts at Googling have failed miserably. If ...
3
votes
1answer
77 views

Is there another explanation, apart from the doppler effect, for the redshift observed in distant galaxies?

On episode 10 of the original Cosmos TV series, Carl Sagan mentions that some scientist don't agree that the redshift observed in distant galaxies is evidence of the big bang, stating that probably ...
3
votes
1answer
46 views

Do galaxies have a preferred orientation?

This article: http://physicsworld.com/cws/article/news/2011/jul/25/was-the-universe-born-spinning asserts that the universe was "born spinning" and that there is a preferred rotation direction for ...
2
votes
2answers
162 views

Galaxies are moving away from each other then how Milkyway and Andromeda galaxy coming towards each other?

The Andromeda Galaxy is approaching the Milky Way at about 684000 mi/hours, making it one of the few blueshifted galaxies. The Andromeda Galaxy and the Milky Way are thus expected to collide in about ...
2
votes
3answers
84 views

Pulsation Modes of Cepheids

There are various modes of Cepheids like single modes: fundamental (F), first overtone (1O), and likewise. And then we have double modes: F/1O, 1O/2O etc. triple modes: 1O/2O/3O etc. ...
2
votes
1answer
45 views

Metallicity: What are the metallicity values of various galaxies?

What are the various values of metallicity of various known galaxies, like Milky Way, Large Magellanic Cloud, Small Magellanic Cloud, Andromeda and so on?
2
votes
2answers
46 views

How many stars are visible to naked eyes around Equator area?

In the best sky conditions, we can see about 44,000 stars in the sky. But what if I am located around Equator area? How many stars I can see? From what I know, the number of stars I can see should ...
2
votes
4answers
146 views

What is the speed of light relative to (in space)?

From what I understand the universe is expanding faster than the speed of light and accelerating so that it's possible that a given galaxy: $A$ will no longer be visible to another given galaxy: $B$. ...
2
votes
1answer
76 views

why are galaxies different in color?

whether its in movies,television,real-life or some planetarium different galaxies are shown in different color. For ex:- Milky way is always seen in Blue where as Andromeda gives out a bit reddish ...
2
votes
2answers
43 views

What is the difference between a dwarf spheroidal galaxy and a globular cluster?

This Wikipedia article states that Segue 1 is either a dwarf spheroidal galaxy or globular cluster associated with our own Milky Way. I am wondering what the difference is between dwarf spheroidal ...
1
vote
2answers
126 views

Age of the universe

A Galactic year is estimated to be around 250 million "terrestrial" years. That means there will be about 4 rotations per billion years. And age of the universe is estimated to be near 13.8 billion ...
1
vote
3answers
131 views

Could light be dark matter?

Is it possible that light itself is dark matter? I am speaking of photons (e.g. visible light, infrared, ultraviolet, etc...). I realize light is understood to be massless, but it is obvious it at ...
1
vote
2answers
56 views

What is meant by “Radial Direction” of a galaxy?

There is a scientific journal article having a line: "In order to study the star formation scenario in the radial direction of the LMC...." What is meant by 'radial direction' of a galaxy ?
1
vote
2answers
51 views

What does “Normalized to Si 10 to the power 6” mean?

I'm writing a space game that I want to give a more "realistic" feel. When looking for a reference as to distribute elements in planets (for mining, etc) Instead of finding the more usual percentage ...
1
vote
3answers
68 views

Quasars and SMBH

Quasars are known to contain supermassive Black Holes at their cores. So does that mean that the number of quasars is equal to that of the SMBHs out there?