Galaxies

Galaxies are large systems of stars and interstellar matter, and they contain billions of stars. Our own galaxy, the Milky Way, has 200 to 400 billion stars, and there are over one billion known galaxies. Questions that have to do with galaxies in general and specific galaxies are perfect for this category!

8,068 Questions
Galaxies
Astronomy
Cosmology

What are the types of galaxies?

The main types of galaxies are Spiral galaxies, Elliptical galaxies, Lenticular galaxies, and Irregular galaxies.

  • Spiral (and Barred-Spiral) galaxies are shaped like pinwheels, with arms that spiral outward. The barred spiral has an elongated bar shape across the middle. Examples of the spiral are our own Milky Way and Andromeda. A barred spiral is the Sculptor Galaxy.
  • Elliptical galaxies look like flattened spheres rather than the thinner spiral form. They are observed to have comparatively little interstellar matter. An example is the Maffei 1 galaxy.
  • Lenticular galaxies are flattened galaxies without an obvious spiral structure. An example is the Spindle Galaxy in Draco.
  • Irregular galaxies do not have any of the common shapes, and may have been disrupted by various forces. These include Hoag's Galaxy (a ring), the Magellanic Clouds, and NGC 1427A (which is speeding toward the Fornax cluster).

See related link for more information

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Astronomy
Galaxies

How do active galaxies differ from normal galaxies?

Those nuclei are associated with a supermassive black hole. Basically all galaxies have a supermassive black hole, but some are more active than others - apparently when they are in the process of ingesting matter, and have a large accretion disk.

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Astronomy
Galaxies

What can astronomers conclude based on the observed red shifts in the spectral lines of distant galaxies?

The strongest consensus (nearunanimous of the astronomical community is that the redshifts of distant galaxies indicate that all distant galaxies arerecedingfrom us. This recession is currently the only known mechanism for redshifting light. Take this inference, that all galaxies arereceding and you are led to the idea that the universe is expanding, a phenomena described by Hubble's Law. This is a central tenet to the Big Bang Theory.

I will include the counterpoint originally described below, but I will point out that the papers cited are very old, and a huge number of corroborating observations and predictions of the big bang haveoccurredsince then.


The conclusion that the Universe is expanding is a wrong conclusion. Alan Sandage talks about Hubble's position at the related link below.

To the very end of his writings he maintained this position, favouring (or at the very least keeping open) the model where no true expansion exists, and therefore that the redshift "represents a hitherto unrecognized principle of nature". This viewpoint is emphasized (a) in The Realm of the Nebulae, (b) in his reply (Hubble 1937a) to the criticisms of the 1936 papers by Eddington and by McVittie, and (c) in his 1937 Rhodes Lectures published as The Observational Approach to Cosmology (Hubble 1937b). It also persists in his last published scientific paper which is an account of his Darwin Lecture (Hubble 1953).

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Galaxies

How far is the nearest galaxy?

  • Milky Way Galaxy - Our Galaxy
  • Omega Centauri - former galaxy - 0.0183 million light years away
  • Canis Major Dwarf - 0.025 million light years away
  • Virgo Stellar Stream - 0.03 million light years away
  • Sagittarius Dwarf Elliptical Galaxy - 0.81 million light years away
  • Large Magellanic Cloud - 0.163 million light years away
  • Andromeda Galaxy - Largest - 2.5 million miles away.

The Canis Major Dwarf Galaxy orbits the Milky Way at 42,000 light years from the galactic center. The Sagittarius Dwarf Elliptical Galaxy orbits at 50,000 light years. The Large and Small Magellanic Clouds are also very close to the Milky Way, but there is some debate over whether they are "orbiting" the larger galaxy. However, orbiting or not, they are still considered "satellites" of the Milky Way. All of these galaxies are very small compared to the Milky Way and most are irregular in shape, all of them lacking the spiral structure normally associated with a well-organized galaxy. The Phoenix Dwarf Galaxy is 1.44 million light years from the center of the Milky Way, and NGC 6822 (aka Barnard's Galaxy) is 1.6 million light years away.

See related link for more information.

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Stars
Galaxies
Nuclear Physics

What causes the sun to produce light?

Heat from nuclear fusion produces massive amounts of energy. Thermal energy is usually associated with Light. The concept of heat creating light is the same basis as to why light bulbs get hot when you turn them on, or why metal gets bright red when you heat it up.

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Astronomy
Galaxies

Who narrated the National Geographic Inside the Milky Way?

Actor Reg E. Cathey narrated National Geographic's "Inside The Milky Way".

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Planetary Science
Stars
Galaxies

What do you call people who study planets and stars?

Astronomers.

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Astronomy
Planetary Science
Galaxies
Milky Way Galaxy

Are the pleiades bigger than the milky way galaxy?

No. The Pleiades is an open cluster of a few thousand stars within the Milky Way.

The Pleiades is a group of stars about 2 degrees across, at a distance of 600 light years. That means it is about 20 light years from one side of the Pleiades to the other, but that it still much less than the size of the Galaxy. From the Pleiades, the Sun would appear as a 9th magnitude star, with Sirius nearby at magnitude 6.

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Planetary Science
Galaxies

What is the name milky way twin galaxy?

Probably not a twin, but certainly similar - the Andromeda galaxy.

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Astronomy
Galaxies
Black Holes

What evidence is there for galactic supermassive black holes?

Our galaxies all need the middle part of our galaxies the quasar which balances our galaxies and is one of the most powerful things in the universe we know. It is super energetic and everything around it which is the solar system it is in the middle of it makes it spin around it at almost the speed of light. Our solar system revolves around the quasar and the quasar keeps all the other solar systems in our solar system together including us.

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Astronomy
Galaxies
Constellations

What is meant by a star's altitude?

The angle you have to raise your chin to go from looking straight at the horizon to looking straight at the star.

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Astronomy
Planetary Science
Galaxies
Milky Way Galaxy

Can you see distant galaxies in the milky way?

If you mean 'Are there any distant galaxies embedded within the Milky Way, the answer is no. Distant galaxies are completely separate from the Milky Way, and many can be seen through telescopes. A small number appear as stars to the naked eye. Everything we see, we see through the Milky Way, since it is the galaxy we live in. It is all around us; we cannot avoid looking through it. Some parts of the Milky Way, especially near the center, are so dense with clouds of dust and stars that we can't see much behind it. Apart from that, we can peer into deep space in pretty much any direction.

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Actually, the answer might be "Yes!" Recent researches indicate that galaxies often collide, and sometimes merge. Some somewhat controversial research indicates that our Milky Way may be a sort of "predator galaxy" which "eats" other smaller galaxies. At least one astronomer claims to have found traces of four other galaxies that have been absorbed into the Milky Way!

However, they wouldn't be especially "distant" because they would now be _part of_ the Milky Way.

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Astronomy
Galaxies
Milky Way Galaxy

What is the largest body of the milky way galaxy?

VY Canis Majoris, a red hypergiant in Canis Major, is the largest known star in the Milky Way Galaxy. It is about 3 x 109 kilometers (about 9 AU) in diameter, and located about 5 x 1016 kilometers (about 1.5 kpc) away from us.

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Galaxies
Milky Way Galaxy

What galaxy do we live in?

The milky way

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Galaxies

What do you call multiple universes?

the multi-verse

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Galaxies

What is a galaxy?

A galaxy is a vast, gravitationally bound collection of billions of stars and their associated "friends."

Their "friends" include nebulae, stellar remnants, planets and a whole host of other smaller particles including the basic elements hydrogen and helium. Galaxies also consist of an important but poorly understood substance called dark matter. It is believed to surround every galaxy and accounts for much of its mass.

Galaxies vary in size and shape. They range from dwarfs that may only consist of a few million stars to giants that can have trillions of them, all orbiting a center of mass. Galaxies are categorized based on their apparent shapes. Elliptical galaxies are bright, featureless spheroids consisting mostly of old, low-mass stars. Spiral galaxies are disk shaped and have a variety of stars, and irregular galaxies are a catch-all for those with no distinct shape.

Many galaxies, including the Milky Way, orbit around what is to believed to be a supermassive black hole--smaller than a pinhead but with the mass of millions or billions of Suns. The supermassive black hole in the center of our galaxy flattens it into a disk with a depth of a few light years, whereas the diameter is about 100,000 light years.

It is estimated that there are between 100-300 billiongalaxies in the observable Universe!

  1. A galaxy is system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
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Astronomy
Planetary Science
Galaxies
Milky Way Galaxy

How many years until the Andromeda and Milky Way galaxies collide?

About 3.5 billion years. We won't be around for it.

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Astronomy
Galaxies
Milky Way Galaxy

How many stars are in the Milky Way?

The figure of 200 to 400 billion is considered to be

today's most reliable estimate. (late 2012)

(Minor Comment: It's not clear if this question refers to the whole Milky Way Galaxy or to just the band of stars called the Milky Way.)

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Galaxies
Star Wars Movies

What galaxy is 3 million light years from Earth?

The Triangulum Galaxy (M33 galaxy), a.k.a., the Star Wars galaxy.

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Galaxies

What galaxy super cluster is earth in?

The Earth is part of the Milky Way Galaxy which in turn is part of the Local Group Cluster. The Local Group Cluster itself is part of the Virgo super cluster.

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Astronomy
Galaxies
Constellations
Big Dipper

Does the big dippers stars move?

Yes they do. But they're so far away that you can't see the effects of their motion over the duration of a human lifetime.

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Science
Astronomy
Galaxies

What is the embryonic universe?

Is your mom

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Acronyms & Abbreviations
Galaxies

What is 'NGC'?

It could be any of a number of things, depending on your context; National Geographic Channel, National Guideline Clearinghouse, National Gallery of Canada, National Graduate Caucus, Spiral Galaxy NCG-4565, New general catalogue, New Generation Computing Inc., Northrop Grumman Corporation...and many more.

If you found it on a star map, it almost certainly means "New General Catalogue," which is a listing of so-called "deep sky objects" put together at the end of the 19th century. There are several thousand objects in the catalogue; each is assigned a unique number. The NCG objects include galaxies, nebula, clusters, etc. The NGC is a much more extensive collection than earlier catalogs such as the Messier catalog.

Of course, it could also mean "Nintendo Game Cube" - a previous generation games console.

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Galaxies

What galaxy do earth belongs?

The earth exists on the edge of the Milky Way galaxy.

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Galaxies

What galaxy are we on?

the milky way

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