(December 22, 2022 at 11:53 pm)Anomalocaris Wrote:(December 22, 2022 at 11:12 pm)Gawdzilla Sama Wrote: The alignment would be transitory given that the Earth rotates around the Sun.
It happens once yearly, when the sun transits Sagittarius in late November and December.
However, in the long run, this is not a permanent state of affairs because as the sun revolves around the Milky Way, the ecliptic plane in which the planets orbit the sun does not pivot around in sync. So the sun’s passage through the back ground sky over the course of a year will only appear to take it in front of the center of Milky Way for a period of a few million years every 120 million years. During the rest of the time e the sun never comes anywhere close to passing in front of the center of the galaxy as seen from the earth.
So the sun has been coming roughly between earth and center of the galaxy once each year since approximately when the first hominid walked the African savanna about 3 million years ago. But before that the sun had not been comimg anywhere close to transiting in front of the center of the galaxy since the early Cretaceous period, and before that, just after than Permian Triassic extinction.
Interesting calculation. I wonder how the precession of the equinoxes and changing obliquity would factor into this?
