Autum equinox occurs this year on September 22-23. Equinox is the moment balance, peace, silence, as the sun passes the equator from north to south. Harvest time we reached, and a few hours later, Aries Full Moon Harvest culminates. Year periods globe Wednesday officially changed their anticipated transition to exploit natural astronomical autumn equinox.
The definition of the equinox as a time of night and the day is a convenient simplification. On the one hand, to face the night so simple when the sun is below the horizon, and completely ignores the twilight. If the sun was no longer a point of light in the sky, and if the Earth had no atmosphere, so at the time of the equinox the sun would really spend half of its trajectory over the horizon and half below.
In addition to the refractive speed sunrise sunset and delays, there is another factor that makes the light more at night than at equinox sunrise and sunset are defined as those times when the first or last grain of the limb top of the sun visible on the horizon - not the center of the disc.
This effect of high-refraction also causes the sun disk appears oval when it is near the horizon. The amount of refraction increases as soon as the sun approaches the horizon, its lower end rises above the upper, which distorts the sun, disc significantly.