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Ask an Astronomer: Why Do We See Spiral Arms in Some Galaxies?

1 minutes 54 seconds

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In this episode, scientist Steve Lord explains the relationship between gravity and the shape of galaxies. Gravitational forces from the galaxy's core causes all the stars to rotate. This rotation causes spiral waves. Part of the "Ask an Astronomer" series.

Media Details

Runtime: 1 minutes 54 seconds

An Illustration depicts the three positions of the universe. The difference between the first two and the last two positions is labeled, + 2 units. The difference between the first and last positions is labeled, + 4 units. Caption: the more the expansion pushes them apart.
Ask an Astronomer
Episode 1
2 minutes 34 seconds
Grade Level: 7 - 12
The celestial image of a red starry surface. Caption: Where new stars are born,
Ask an Astronomer
Episode 2
2 minutes 8 seconds
Grade Level: 7 - 12
Sun and a red planet in outer space. Caption: we can tell what comprises the atmospheres.
Ask an Astronomer
Episode 3
3 minutes 4 seconds
Grade Level: 7 - 12
An image of the outer space. Caption: it's eventually blocks out all visible light.
Ask an Astronomer
Episode 4
2 minutes 30 seconds
Grade Level: 7 - 12
A huge mass of hot gas swirls into a star. Caption: that swirls onto the massive star.
Ask an Astronomer
Episode 5
3 minutes 29 seconds
Grade Level: 7 - 12
A galaxy fades out. Caption: The original galaxy would be gone.
Ask an Astronomer
Episode 6
2 minutes 7 seconds
Grade Level: 7 - 12
An electromagnetic spectrum with a bright star over the infrared range. Caption: Hotter objects glow in visible light.
Ask an Astronomer
Episode 7
3 minutes 16 seconds
Grade Level: 7 - 12
illustration of asteroids revolving the sun and other planets. Caption: Asteroids, though, move across the sky at different rates.
Ask an Astronomer
Episode 8
2 minutes 4 seconds
Grade Level: 7 - 12
Illustration of a wave striking an atom. Caption: The shortest wavelength light are gamma rays,
Ask an Astronomer
Episode 9
6 minutes 58 seconds
Grade Level: 7 - 12
Illustration of a woman talking to the Alien M51. Caption: You've got to move the earth back where it belongs.
Ask an Astronomer
Episode 10
4 minutes 26 seconds
Grade Level: 7 - 12