Spiral Galaxies Spiral Galaxies Our Milky Way is one example of a broad class of galaxies defined by the presence of spiral arms. These galaxies resemble giant rotating pinwheels with a pancake-like disk of stars and a central bulge or tight concentration of stars.
How do we know the galaxy is spiral?
The concentration of stars in a band adds to the evidence that the Milky Way is a spiral galaxy. If we lived in an elliptical galaxy, we would see the stars of our galaxy spread out all around the sky, not in a single band.
How can you tell these are spiral galaxies and not elliptical or lenticular galaxies?
First, elliptical galaxies are characterized by a spherical or cucumber-like shape, while spiral galaxies have a central disk surrounded by spiral arms. Moreover, elliptical galaxies contain older, dimmer stars, while spiral galaxies are solar nurseries containing younger, brighter stars.
How are elliptical galaxies identified?
Elliptical galaxies have a smooth ellipsoidal or spherical appearance, and they have far less structure than spiral galaxies do. Elliptical galaxies are typically found in galaxy clusters.
What does a elliptical galaxy look like?
An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the four main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work The Realm of the Nebulae, along with spiral and lenticular galaxies.
Are nebulae often found in elliptical galaxies?
Dust and emission nebulae are not conspicuous in elliptical galaxies, but many do contain a small amount of interstellar matter.