What causes the spiral arms in the Milky Way's disc to appear patterned rather than uniformly bright?
Answer
They are density waves where the concentration of stars and gas is temporarily higher.
The spiral arms are not rigid structures but are density waves—areas where the concentration of stars and gas is temporarily higher as they orbit the galactic center.
Related Questions
Which galaxy is most famously cited as exhibiting a distinct, flattened, disk-like shape?Disc galaxies broadly encompass which primary morphological group of galaxies?What key structural feature distinguishes a lenticular galaxy (S0) from a classic spiral galaxy?What is the estimated diameter of the Milky Way's disc structure?What physical principle dictates that collapsing galactic material must begin to spin?Why does the gas component in a forming disc galaxy settle efficiently into a flat orbital plane?What major evolutionary event tends to disrupt the organized rotation of a disc galaxy, often leading to an elliptical shape?What causes the spiral arms in the Milky Way's disc to appear patterned rather than uniformly bright?How does the rotation speed in the outer parts of the Milky Way's disc compare to predictions based only on visible matter?What fundamental difference exists between the stellar orbits in an elliptical galaxy compared to a disc galaxy?