spiral arm

American  

noun

Astronomy.

1. any of the elongated and curved spiral sections that are connected to the center of a spiral galaxy.

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Etymology

Origin of spiral arm

First recorded in 1910–15

Example Sentences

Since the Radcliffe Wave appears to form the backbone of the nearest spiral arm in the Milky Way, the waving of the wave could imply that spiral arms of galaxies oscillate in general, making galaxies even more dynamic than previously thought.

From Science Daily

A few years ago, astronomers uncovered one of the Milky Way’s greatest secrets: an enormous, wave-shaped chain of gaseous clouds in our sun’s backyard, giving birth to clusters of stars along the spiral arm of the galaxy we call home.

From Science Daily

It also could hold clues to why the Milky Way has its spiral arm.

From Salon

This discovery also connects spiral arm instabilities to the episodic growth bursts - a key factor for how high-mass stars form.

From Space Scoop

Although it is true that comet showers are triggered by passing stars that perturb the inner Oort cloud, such a star has to get relatively close to our sun for the showers to occur, and these events happen extremely infrequently—even during a spiral arm passage.

From Scientific American