Deep Sky Objects explained

This website uses the excellent DSO object database created by the Saguaro Astonomy Club. They have various types of categorisation for their DSOs, and to help explain them, here is the list with an example object that you might be able to see.

Type Explanation Example
Asterism A pattern of stars seen in Earth's sky which is not an official constellation. Kemble's Cascade
Kemble's Cascade
Bright Nebula Large clouds of gas and other particles that shine due to reflected star light or by light emitted due to charged particles interacting with interstellar radiation. Eta Carinae
Eta Carinae
Cluster with Nebulosity Clusters of stars with associate gasses and particles which reflect the stars' light/radiation. Pleiades
Pleiades
Globular Cluster A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. 47 Tucanae
47 Tucanae
Galaxy A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, and an interstellar medium of gas and dust. M31 Andromeda
M31 Andromeda
Galaxy Cluster Groups of galaxies which are the largest known gravitationally bound objects to date. Coma I
Coma I
Globular Cluster in a Galaxy A spherical collection of stars that orbit a galactic core in a galaxy outside of the Milky Way. NGC 1049
NGC 1049
Cluster with Nebulosity in the Large Magellanic Cloud Clusters of stars with associate gasses and particles which reflect the stars' light/radiation, located within the LMC. Tarantula
Tarantula
Open Cluster A group of up to a few thousand stars formed from the same giant molecular cloud which are still loosely gravitaionally bound to eachother. Hyades
Hyades
Planetary Nebula A nebula consisting of an expanding glowing shell of ionized gas and plasma ejected by certain types of stars late in their life. Named 'planetary' because of their similarity in appearance to giant planets when viewed through small telescopes, but is otherwise unrelated to planets. Helix
Helix
Quasar A quasi-stellar radio source (quasar) is a very energetic and distant galaxy with an active galactic nucleus. Quasars were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies. 3C 273
3C 273
Cluster with Nebulosity in the Small Magellanic Cloud Clusters of stars with associate gasses and particles which reflect the stars' light/radiation, located within the SMC. NGC 346
NGC 346
Globular Cluster in the Small Magellanic Cloud A spherical collection of stars that orbit the galactic core of the SMC. NGC 419
NGC 419
Open Cluster in the Small Magellanic Cloud A group of up to a few thousand stars formed from the same giant molecular cloud which are still loosely gravitaionally bound to eachother, in the SMC. NGC 220
NGC 220
Supernova Remnant A supernova remnant is the structure resulting from the gigantic explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way. Western Veil
Western Veil
Double stars (2 star) a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary system of stars in mutual orbit, gravitationally bound to each other, or because it is an optical double, a chance alignment of two stars in the sky that lie at different distances. Winnecke 4
Winnecke 4