What Are Elliptical Galaxies, How Do Elliptical Galaxies Form, and Why Do They Contain Mostly Old Stars?

Elliptical galaxies in our universe have the shapes of ellipses, or stretched-out circles.

They can be egg-shaped, almost round, or almost flat.

The astronomer Edwin Hubble created a scale from 0 to 7 to designate the roundness of an elliptical galaxy. An elliptical galaxy that is almost round is called E0, while one that is almost flat is E7.

It is now believed that elliptical galaxies may be the result of a process where two galaxies of any type and similar mass, collide and merge.

Elliptical galaxies contain mostly old stars, with little gas and dust.

Very little new star formation is thought to occur, because of the lack of gas, dust, and space.

Elliptical galaxies come in gradations of roundness.

Edwin Hubble’s classification of galaxies designates the different varieties EO to E7, counting from most round to almost flat.