Solar System
Comets and planets

Normal Stars & Star Clusters
Stellar coronas, clusters of stars and hot gas produced by outflow from young stars.

White Dwarfs & Planetary Nebulas
Hot gas associated with the final stages of evolution of Sun-like stars, novas, and other white dwarfs in binary star systems.

Supernovas & Supernova Remnants
X-ray sources produced by the violent explosions of massive stars.

Neutron Stars/X-ray Binaries
Hot, isolated neutron stars, rotation-powered pulsars, and neutron stars accreting matter from a nearby companion star.

Black Holes
Stellar black holes, mid-mass black holes, and supermassive black holes.

Milky Way Galaxy
Images related to the Galactic Center and other features of the structure and evolution of the Milky Way Galaxy.

Normal Galaxies & Starburst Galaxies
Images of spiral, elliptical, and irregular galaxies that show X-ray sources associated with collapsed stars and star formation.

Quasars & Active Galaxies
Galaxies with unusually energetic activity, including high-energy jets, that is related to a central supermassive black hole.

Groups & Clusters of Galaxies
Vast clouds of hot gas embedded with numerous galaxies.

Cosmology/Deep Fields/X-ray Background
The sky as observed in X-rays is not dark, but gives off a glow thought to be from many distant sources. Deep surveys with the Chandra X-ray Observatory should reveal the cause of this glow.

Miscellaneous
Objects that don't fit in the above categories, such as brown dwarfs & gamma-ray bursts.