Summer Solstice: tomorrow is the longest day of the year & International Yoga DayJune 21st and December 21st are the two longest days of a year. It is generally referred to as Solstice, meaning an event occurring when the Sun appears to reach its most Northerly or Southerly excursion relative to the celestial equator on the celestial sphere. June solstice is referred to as the Summer Solstice in the Northern hemisphere and winter solstice in the Southern hemisphere.
The longest day of the year technically means that the Sun reaches in the highest point in its path, as seen from the Earth, and the tilt of the Earth's axis is most inclined towards the Sun.
An Indian led resolution passed by United Nations' General Assembly has declared June 21st as 'International Yoga Day'.