Curious About Astronomy: How are galaxies formed?


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** How are galaxies formed? **

/I am sixth grader and I am doing a science project on galaxies. I wanted
to know how galaxies are formed./

As you may know, galaxies are mainly of two kinds: spiral galaxies and
elliptical galaxies (there are also irregular galaxies).

Spiral galaxies form from the collapse of a protogalactic cloud. Spiral
galaxies consist of three components: a rotating disk, a bulge and a halo.
When the protogalactic cloud collapses, the stars in the bulge and halo
form first. These stars have rather random orbits around the galactic
center. The remainder of the cloud forms a disk due to the conservation of
angular momentum (the same effect as the spinning up of the dancer when


how are galaxies formed

Galaxy formation and evolution - Wikipedia, the free encyclopedia


** Galaxy formation and evolution **

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Part of a series on
Physical cosmology
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· Universe
· Big Bang
· Age of the universe
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Early universe

· Inflation
· Nucleosynthesis
· Neutrino background
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Expanding universe

· Redshift
· Hubble's law
· Metric expansion of space
· Friedmann equations
· FLRW metric

Structure formation

· Shape of the universe
· Structure formation
· Reionization
· *Galaxy formation*
· Large quasar group
· Large-scale structure
· Galaxy filament

Future of universe

· Ultimate fate of the universe
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The study of *galaxy formation and evolution* is concerned with the
processes that formed a heterogeneous universe from a homogeneous
beginning, the formation of the first galaxies, the way galaxies change
over time, and the processes that have generated the variety of structures
observed in nearby galaxies. It is


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