User talk:81.226.17.170

The entry about the Pinwheel galaxy states that the diameter of M101 (the Pinwheel) is 170,000 light-years. This would seem to be correct. However, the entry also states that the diameter of the Milky Way is 258,000 light-years. This seems to be erroneous. At the very least, the figures measure the diameters of the Milky Way and the Pinwheel Galaxy differently. For the Pinwheel, the number seems to refer to the obviously luminous disk of the galaxy. For the Milky Way, it seems to refer to the size of the invisible dark matter halo, or, alternatively, to an outer baryonic matter halo which is, however, so tenuous and faint that it will never show up on normal optical photographs of the obviously luminous disk.AnnSidb (talk) 20:14, 15 March 2019 (UTC)