What are nebulae? What galaxy is nearest to Milky Way?
Andromeda is NOT the closest galaxy to the Milky Way. At 2.2 million light-years distance, It is only the closest “of comparable size.” The closest galaxy is the “Sagittarius Dwarf” at 70,000 light-years. This small galaxy went unnoticed until its discovery in 1994. The reason the Sagittarius Dwarf hadn’t been discovered earlier is because it is so dim, it is so spread out over the sky, and there are so many Milky Way stars in front of it. A nebula (Latin: “mist”; pl. nebulae or nebulæ, with ligature) is an interstellar cloud of dust, gas and plasma. Originally nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way (some examples of the older usage survive; for example, the Andromeda Galaxy is sometimes referred to as the Andromeda Nebula). They are the birthplace of stars.
