The Galactic Center is the rotational center of the Milky Way galaxy. It is located about 8 kiloparsecs (26,000 LY) away from the Earth, in the direction of the constellation Sagittarius, where the Milky Way appears brightest.
Proof of existence and location
Because of cool interstellar dust along the line of sight, the Galactic Center cannot be studied at visible, ultraviolet or soft X-ray wavelengths. The available information about the Galactic Center comes from observations at gamma ray, hard X-ray, infrared, sub-millimetre and radio wavelengths.
The complex radio source Sagittarius A appears to be located almost exactly at the Galactic Center, and contains an intense compact radio source, Sagittarius A*, which many astronomers believe may coincide with a supermassive black hole at the center of our Galaxy. Accretion of gas onto the black hole, probably involving a disk around it, would release energy to power the radio source, itself much larger than the black hole. The latter is too small to see with present instruments.
Work presented in 2002 by Antony Stark and Chris Martin mapping the gas density in a 400 light year region around the galactic center has revealed an accumulating ring with a mass several million times that of the Sun and near the critical density for star formation. They predict that in approximately 200 million years there will be an episode of starburst in the galactic center, with many stars forming rapidly and undergoing supernovas at a hundred times the current rate. The starburst may also be accompanied by the formation of galactic jets as matter falls into the central black hole. It is thought that the Milky Way undergoes a starburst of this sort every 500 million years.
Several authors have predicted a special astrological/astronomical alignment between the Galactic center in the constellation (not the sign!) of Sagittarius, the Winter Solstice point, and the constellation of the Pleiades in the year 2012. The predicted alignments are conjuctions (close to 0 degrees separation) and opposition (180 degrees separation)
While of no scientific significance, several details are worth noting for purposes of occasional discussion if scientists are asked about the event.
Factually, the coincidence by conjuction of the Winter Solstice point (via Precession of the Equinoxes) and the galactic center is basically true. However, the predicted opposition of the Pleiades is not true.
The source of this confusion seems to be in misunderstanding the Precession of the Equinoxes, a phenomena which has resulted in the astrological signs beings out of synch with the corresponding constellations by about 30 degrees.
The Pleiades are located in the constellation (not the sign!) of Taurus, and currently lie at an angle of about 150 degrees to the Galactic Center. The Pleides would have to to be located in the constellation (not the sign) of Gemini to be close to being in opposition (a 180 degree angle). (The angle of 150 degrees is low in astrological significance.)
Further, the proper motion of the stars in the Pleiades Cluster is such that they moving across the sky relative to Earth. This takes place quite slowly as seen on the human time scale. Three million years ago the Pleiades were seen near the constellation of Cassiopeia. Three million years in the future, they will appear near the feet of Orion. This is easily validated using programs such as the freeware Move A Star, which allows one to observe the proper motion of many bright stars over an extended period of time.
The Pleiades have never been, and never will be, in 'opposition' to the galactic center as seen from Earth.
- UCLA Galactic Center Group
- Max Planck Institute for Extraterrestrial Physics Galactic Center Group
- Dramatic Increase in Supernova Explosions Looms
- Fast Stars Near the Galactic Center APOD
- At the Center of the Milky Way APOD
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