SUMMER SOLSTICE DAY

SUMMER SOLSTICE DAY

Monday, June 21^st, 2010

Longest day of the year !!!!

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 2010, the solstice occurs in the Northern Hemisphere on June 21, at 11:28 UT, i.e. at 16:58 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 2010 is at 5:24 am and sunset is 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.

June 21 is called the summer solstice in the Northern Hemisphere and simultaneously the winter solstice in the Southern Hemisphere. Around December 21 the solstices are reversed and winter begins in the Northern hemisphere.

Summer Solstice Event conducted by SPACE:

To celebrate summer solstice, SPACE will be performing public outreach at Jantar Mantar, New Delhi on Monday, 21^st June. Educators from SPACE will be measuring the sun angle and the sun’s declination using the Ram Yantra and the Jai Prakash Yantra instruments. They will also explain the various instruments at Jantar Mantar to the public. All media and public are invited to attend this event.

Details:

Summer Solstice: June 21, at 11:28 UT, i.e. at 16:58 IST

Event: SPACE will conduct Public Outreach and Activities

Location: Jantar Mantar, New Delhi

Date and Time: Monday, 21^st June, 2010 from 11:00 AM to 1:00 PM

For more information about the article/event contact Jaishree at SPACE at 9212669934.