Guided Exploration: Galaxy Zone

 

HoU Tour Map: Galaxy

Overview: Galaxies contain dark matter, gas, dust, and billions of stars, held together by gravity. This matter orbits a common center of mass, and that orbital motion prevents the galaxy from collapsing under gravity’s pull. The shape of a galaxy (spiral, elliptical, or irregular) depends on how it formed. This zone explores galactic formation and evolution, and what happens when galaxies collide.

1. Galaxy Wall

Examine the photos and animations to compare and contrast the different types of galaxies. What do the three main types have in common? How are they different?

What is a galaxy?

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What is a Galaxy?

Galaxies are titanic swarms of tens of millions to trillions of stars, orbiting around their common center of gravity.



Spiral Galaxies

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Spiral Galaxies

Spiral galaxies have three visible parts: a thin disk composed of stars, gas, and dust; a central bulge of older stars; and a spherical halo of the oldest stars and massive star clusters.


Elliptical Galaxies

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Elliptical Galaxies

Elliptical galaxies have smooth, rounded shapes because the orbits of their stars are oriented in all directions.


Irregular Galaxies

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Irregular Galaxies

Irregular galaxies have a chaotic appearance, and are usually small.


Other galaxy classifications_HERO

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Other Galaxy Classifications

The classification of galaxies by shape relies upon images made with visible light. But galaxies observed in other wavelengths, or with longer exposure times, or at earlier cosmic epochs, show the need for additional categories.


2. Interacting Galaxy Cluster

Watch the video in the center to see how gravity causes galaxies to merge and collide. What happens when they collide?

Interacting galaxies

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Interacting Galaxies

Galaxies are grand yet fragile structures. When they pass close to each other or collide, their mutual gravity pulls them apart, twisting and distorting their shapes.