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The Cat's Eye Nebula (also known as NGC 6543 and Caldwell 6) is a planetary nebula in the northern constellation of Draco, discovered by William Herschel on February 15, 1786. It was the first planetary nebula whose spectrum was investigated by the English amateur astronomer William Huggins , demonstrating that planetary nebulae were gaseous ...
Iris Nebula: Open Cluster and Nebula: 1.4 Cepheus: 7 C5 IC 342: Hidden Galaxy [7] Spiral Galaxy: 10,000 Camelopardalis: 9 C6 NGC 6543: Cat's Eye Nebula: Planetary Nebula: 3 Draco: 9 C7 NGC 2403 Spiral Galaxy: 14,000 Camelopardalis: 8.4 C8 NGC 559 Open Cluster: 3.7 Cassiopeia: 9.5 C9 Sh2-155: Cave Nebula: Nebula: 2.8 Cepheus: 7.7 C10 NGC 663 ...
Messier 94 (also known as NGC 4736, Cat's Eye Galaxy, Crocodile Eye Galaxy, or Croc's Eye Galaxy [7] [8]) is a spiral galaxy in the mid-northern constellation Canes Venatici. It was discovered by Pierre Méchain in 1781, [ 9 ] and catalogued by Charles Messier two days later.
Eskimo Nebula or Clown Face Nebula: NGC 2392: 1787 2.9 (approx.) 10.1 Gemini: Cat's Eye Nebula: NGC 6543: 1786 3.3 ± 0.9 9.8B Draco: Little Ghost Nebula: NGC 6369: 1800 (prior to) 2 ± 3 9.9 Ophiuchus: Medusa Nebula: Abell 21 1955 1.0 (approx.) 15.99 Gemini: Jewel Bug Nebula: NGC 7027: 1878 3.0 (approx.) 10 Cygnus: Helix Nebula: NGC 7293: 1824 ...
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs ) to Earth.
One such massive cluster is Abell 2218, located at a distance of 3 billion light-years (redshift 0.171). Draco is home to several double stars and binary stars. Eta Draconis (traditionally called Athebyne [ 3 ] ) is a double star with a yellow-hued primary of magnitude 2.8 and a white-hued secondary of magnitude 8.2 located south of the primary.
At the present time the proper distance equals the comoving distance since the cosmological scale factor has value one: () =. The proper distance represents the distance obtained as if one were able to freeze the flow of time (set d t = 0 {\displaystyle dt=0} in the FLRW metric) and walk all the way to a galaxy while using a meter stick. [ 2 ]
Using a prism to disperse their light, William Huggins was one of the earliest astronomers to study the optical spectra of astronomical objects. [14] On August 29, 1864, Huggins was the first to analyze the spectrum of a planetary nebula when he observed Cat's Eye Nebula. [10]