SUMMER SOLSTICE DAY
Tuesday, June 21st, 2011
Longest day of the year!
June 21st will mark the beginning of summer in the northern hemisphere and is called the summer solstice. It is the longest day for people living in the northern hemisphere. In 2011, the solstice occurs in the Northern Hemisphere on June 21, at 17:16 UT (22:46 IST).
June 21 is a very important day for our planet in its relationship with the sun. June 21 marks the beginning of summer in the northern hemisphere and is called the summer solstice. It simultaneously heralds the beginning of winter in the southern hemisphere. It is the longest day for people living in the northern hemisphere. In 2011, the solstice occurs in the Northern Hemisphere on June 21, at 17:16 UT (22:46 IST).
The name is derived from Latin sol (sun) and sistere (to stand still), because at the solstice, the Sun appears to stands still in its movement during its motion (it appears to travel slowly).
The earth spins around its axis, an imaginary line going right through the planet between the north and south poles. The axis is tilted somewhat off the plane of the earth's revolution around the sun. The tilt of the axis is 23.5 degrees; and thanks to this tilt, we enjoy the four seasons. For several months of the year, one half of the earth receives more direct rays of the sun than the other half. Days are longer in the summer for the northern hemisphere due to the tilt of the Earth's axis allowing for more sunlight to be projected onto the surface.
At the June solstice, Earth is positioned in its orbit so that the North Pole is leaning 23-and-a-half degrees toward the sun. As seen from Earth, the sun is directly overhead at noon 23-and-a-half degrees north of the equator, at an imaginary line encircling the globe known as the Tropic of Cancer. The sun's rays are directly overhead along the Tropic of Cancer (the latitude line at 23.5° north, passing through Mexico, Saharan Africa, and India). This is as far north as the sun ever gets. This results in the longest day of the year. For example in New Delhi, sunrise on summer solstice day in 2011 will be at 5:24 am and sunset will be at 7:22 pm making it a day which is almost 14 hours duration.
When the axis tilts towards the sun, as it does between June and September, it is summer in the northern hemisphere but winter in the southern hemisphere. Alternatively, when the axis points away from the sun from December to March, the southern hemisphere enjoys the direct rays of the sun during their summer months. All locations north of the equator have day lengths greater than 12 hours at the June solstice. Meanwhile, all locations south of the equator have day lengths less than 12 hours. Around December 21 the solstices are reversed and winter begins in the Northern hemisphere.
Cultures around the world, starting from historical times, mark this special day in celebration of the sun’s powers.
Summer Solstice Event conducted by SPACE Foundation:
To celebrate the summer solstice, SPACE Foundation will perform public outreach at Jantar Mantar, New Delhi on Tuesday, 21st June. SPACE team would also celebrate a Solar Fest where a small skit would be performed. All media and public are invited to attend this event.
Details:
Summer Solstice: June 21, 22:46 IST (17:16 UT)
Event: SPACE will conduct Public Outreach and Solar Fest (solar observations through pin-hole camera and ball projectors)
Location: Jantar Mantar, New Delhi
Date and Time: Tuesday, 21st June, 2011; 11 am to 2 pm
For more information log on to www.space-india.org
Contact Apoorva 09212669953 or Aakanksha 09212669920.
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