Complex sentence: Bulges were historically thought to be elliptical galaxies that happen to have a disk of stars around them, but high resolution images using the Hubble Space Telescope have revealed that many bulges have properties that are more like spiral galaxies.
Split into simpler sentences: Bulges were historically thought to be elliptical galaxies that happen to have a disk of stars around them. Yet, high resolution images, using Hubble Space Telescope reveal that many bulges have properties that are more like spiral galaxies.