Noon (also midday or noon time) is usually defined as 12 o'clock in the daytime. The term midday is also used colloquially to refer to an arbitrary period of time in the middle of the day. Solar noon is when the sun crosses the meridian and is at its highest elevation in the sky, at 12 o'clock apparent solar time. The local or clock time of solar noon depends on the longitude and date. The opposite of noon is midnight.