In this Grade 6 Earth Science lesson from Chapter 22, students learn about the size, shape, and structure of the Milky Way galaxy, including its disk shape, central bulge, and location of our solar system within it. Students also analyze how galaxies are classified by shape and explore the characteristics of galactic centers, including the concept of quasars. A hands-on experiment helps students understand why the Milky Way appears as a hazy band of light from Earth's edge-on perspective inside the galaxy's disk.
Section 1
Galaxies Display Different Sizes and Shapes
Astronomers classify galaxies into three main types: spiral galaxies with curving arms, egg-shaped elliptical galaxies containing older stars, and irregular galaxies without definite shapes. Galaxies range from 100 million to over a trillion stars.
Section 2
Stars Orbit Around Galactic Centers
Stars in the Milky Way orbit around the galaxy's center at high speeds. Despite this velocity, our Sun takes about 250 million years to complete one orbit due to the galaxy's enormous 100,000 light-year diameter.
Section 3
Black Holes Anchor Galaxy Centers
Most large galaxies contain invisible supermassive black holes at their centers. These giants have masses millions or billions of times greater than our Sun and create bright regions called quasars by pulling in gases from nearby stars.
Section 4
Galaxies Collide and Transform Each Other
When galaxies collide, their stars rarely crash into each other because of the vast distances between them. However, these collisions can change galaxy shapes, with larger galaxies sometimes absorbing smaller ones completely.
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Section 1
Galaxies Display Different Sizes and Shapes
Astronomers classify galaxies into three main types: spiral galaxies with curving arms, egg-shaped elliptical galaxies containing older stars, and irregular galaxies without definite shapes. Galaxies range from 100 million to over a trillion stars.
Section 2
Stars Orbit Around Galactic Centers
Stars in the Milky Way orbit around the galaxy's center at high speeds. Despite this velocity, our Sun takes about 250 million years to complete one orbit due to the galaxy's enormous 100,000 light-year diameter.
Section 3
Black Holes Anchor Galaxy Centers
Most large galaxies contain invisible supermassive black holes at their centers. These giants have masses millions or billions of times greater than our Sun and create bright regions called quasars by pulling in gases from nearby stars.
Section 4
Galaxies Collide and Transform Each Other
When galaxies collide, their stars rarely crash into each other because of the vast distances between them. However, these collisions can change galaxy shapes, with larger galaxies sometimes absorbing smaller ones completely.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter