| Milky Way | is a part of Local Group |  |
| has definition System of approximately 100000 million stars, of which our Sun is one. It is a normal spiral galaxy of class Sb, with a diameter now reckoned to be probably less than 100,000 light-years, and a strong but obscure energy source at the center (emitting infrared radiation). It is undergoing galactic rotation. Possibly one tenth of the galaxy's total mass - estimated at 1.8 × 1011 solar masses - comprises interstellar gas and dust. | |
| has definition The galaxy to which the Sun belongs. Our Galaxy is about 1010 years old and contains about 1011 stars. Its mass is at least 1011 Msun, about 5-10 percent of which is in the form of gas and dust. Diameter ~ 30 kpc; thickness of nuclear bulge about 4 kpc; thickness of disk about 700-800 pc; distance between spiral arms about 1.4 kpc. Mv = - 20.5. Mean density about 0.1 Msun per cubic parsec. Magnetic field about 3-5 × 10-6 gauss. Total luminosity about 1044 ergs s-1 | |
| has definition Our own galaxy, the second largest in the local group. | |
| has definition A softly glowing band of light that bisects the skies of Earth, produced by light from stars and nebulae in the galactic disk. | |
| is an instance of galaxy containing Cepheids | |
| is an instance of spiral galaxy | |
| is an instance of naked eye object | |
| is an instance of hypergalaxy | |
| spiral galaxy | has classification criterion Subdivided according to the openness of the spiral arms as Sa spiral, Sb spiral or Sc spiral. | |
| has mass 1010 to 1012 Msun | |
| galaxy containing Cepheids | has distance determined from Cepheid period-luminosity relation | |
| has number of Cepheids | |
| galaxy | has number of stars 106 to 1012 | |
| has catalog galaxy catalog | |
| collection of galaxies | has number of galaxies | |
| physical object | has location or center of gravity | |
| has angular momentum | |
| has velocity | |
| has momentum | |
| has temperature | |
| has volume | |
| has extent | |
| has material | |
| celestial body | has spectra | |
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