A beer bottle is a bottle made to contain beer, usually made of glass and comes in various sizes, shapes, and colors (usually brown or green). Dark amber or brown glass greatly reduces the presence of UV light, a contributing factor of beer spoilage. However, lighter-colored bottles are often used for marketing reasons.
The vernal equinox occurs on March 20 or 21 and the autumnal equinox on September 22 or 23, marking the beginning of spring and autumn, respectively, in the Northern Hemisphere (and the reverse in the Southern Hemisphere). The days on which an equinox falls have about equal periods of sunlight and darkness.