BellaOnline Forums Education Astronomy The solstice is coming

Each day for six months after the winter solstice, the Sun rises a bit higher in the sky. It reaches the maximum height at the summer solstice, the longest day. Evidence of rituals and festivals at the times of the solstices goes back thousands of years.

Summer Solstice - St John's Day

Although the northern hemisphere coming up to the summer solstice, of course the southern hemisphere is headed for winter.

For six months, each day has been shorter than the last, the Sun lower in the sky. Will it disappear altogether and leave the people bereft in the dark cold winter? The winter solstice is the shortest day of the year and is associated with more festivals than any other astronomical event.

Winter Solstice

Here's a diagram that shows how the sunlight falls on the Earth at a solstice. The Earth's axis is tilted, but the direction of the tilt doesn't change as we orbit the Sun.

Note: The tilt is shown differently in the two diagrams. It doesn't make any difference which way it's depicted - it depends on the viewpoint you're imagining.

I love the long summer nights of the higher latitudes. Follow the lines of latitude even of southern Britain, and you're in Canada. So I love the summer solstice and summer solstice sunrise at Stonehenge is magical. This is one of my favorite pictures, taken by a photographer friend of mine.

Credit & Copyright: Max Alexander, STFC, SPL

Deborah Byrd of EarthSky:

In Great Britain the solstice occurs at 5:25 a.m. BST on June 21. It will also be on June 21st for everywhere east of Greenwich. In the opposite direction, in New York City and the eastern seaboard of the USA, it will be 12:25 a.m. EDT on June 21. But in Chicago and the central zone, the time will be 11:25 p.m. CDT on June 20. And it will also be June 20 for everywhere further to the west.

Astronomers use a celestial coordinate system to describe locations in the sky. It's as though Earth's grid lines were projected into the sky. The celestial equator corresponds to the earthly one.

The ecliptic is the path the Sun appears to take through the sky. (It's actually the Earth that's moving.) It's tilted 23.5 degrees to the celestial equator.

In astronomy a solstice isn't a daylong event, but it occurs at a specific time. The northern summer solstice occurs when the celestial equator reaches its maximum height above the ecliptic. Here's a diagram showing the ecliptic and the celestial equator.

The solstice occurred at 4:24 UTC today. (See previous post in this thread.)

Google has greeted the summer solstice with a doodle. It's a cute animation.

Lots of nice solstice pictures. Here are three:

1. It's the winter solstice in South America. In Cochabamba, Bolivia a man raises his arms to receive the first beam of the rising Sun. The solstice coincides with the Aymara New Year. [Photo: David Mercado]

2. On Selsley Common, Gloucestershire, England two harpists welcome the rising solstice Sun. [Photo: Simon Pizzey]

3. And of course, Stonehenge at the summer solstice is a must. [Photo: John Rainford]