The Summer Solstice 2010 is the longest day in the Northern Hemisphere. At 7:28 a.m. EST on June 21, 2010, the first day of summer officially began and brings with it the most daylight hours for the Northern Hemisphere.
The summer solstice results from the tilt of the Earth's north-south axis to 23.5 degrees relative to the sun. On the summer solstice, the earth's axis tilts the North Pole toward the sun, closest in proximity than at any other point during the year. The sun appears at it's highest point, known as the zenith, in the Northern Hemisphere during the summer solstice at high noon. The summer solstice marks the day the earth receives the greatest amount of sunlight as well though it does not necessarily mean that it will be the hottest day of the year.
For those living in the Southern Hemisphere of the earth, June 21m 2010 brings the onset of winter. While people in the Northern Hemisphere celebrate the longest day of the year, the Southern Hemisphere observes the Winter Solstice or the shortest day of the year.