Happy Summer Solstice 2010

June 21, 2010 09:35 by scibuff

Today the Sun reaches its northernmost point in planet Earth’s sky. It is a widespread misconception that summer “officially” starts on the day of the summer solstice, June 21 or 22, which is the longest day of the year. Many believe that there is some valid scientific reason for doing it that way. However, no scientific or governmental body has ever formally declared that summer starts on the solstice.

Sunrise Solstice at Stonehenge

Sunrise Solstice at Stonehenge. The above image was taken during the week of the 2008 summer solstice at Stonehenge in United Kingdom, and captures a picturesque sunrise involving fog, trees, clouds, stones placed about 4,500 years ago, and a 5 billion year old large glowing orb. Even given the precession of the Earth's rotational axis over the millennia, the Sun continues to rise over Stonehenge in an astronomically significant way - Credit: APOD/Max Alexander, STFC, SPL

Certainly there is no good scientific reason for doing so. In the Northern Hemisphere the period of maximum daylight falls roughly between May 7 and August 7–in other words, the six weeks before and after the solstice. The period of maximum temperature, on the other hand, is June 4 through September 3. (The period of max temperature in the mid-latitudes always lags about 25 to 30 days behind the period of max daylight, due to the fact that the earth heats up and cools off relatively slowly.)

Sunrise Solstice at Stonehenge

In 2005, thousands of people gathered at sunrise to see the sun rise through the 4,000 year old solar monument - Credit: APOD/ Pete Strasser (Tucson, Arizona, USA)

Here is what the Bad Astronomer has to say about the beginning of season.

Sources: Wikipedia, The Straight Dope, Bad Astronomy / Bad Seasons