Reality → Scale → Macro world → Our galaxy
The Milky Way, an accumulation of around two hundred billion stars, measures about 100,000 lightyears in diameter and on average about 3,000 lightyears in thickness. The structure apparently consists of a central bulge and 2- 4 spiral arms arranged in a disc. Our solar system is inconspicuously located in one of the spiral arms [1] . If we fit our galaxy in a stadium, our complete solar system (reaching far beyond the last planet) would be represented by a pea located about halfway between center and rim of the stadium. The galaxy is rotating around its center and it has been estimated that it takes about 200 million years for our Sun to complete a circle [2] .
Our Sun is located in the Orion arm, a minor spiral arm of the Milky Way, at a distance of about 26,000 lightyears from the galactic center.
The Sun's orbital speed around the galactic center has been calculated from measurements of the stars' movements. The deduced speed is incompatible with the galactic mass deducted from other measurements. Most astronomers and physicists explain the apparent discrepancy with the existence of additional unknown matter.