Summer Solstice: 4 Myths About the Sun's Ascension

June 21, 2011— -- From Chalchuapa, El Salvador, to Stonehenge in England, people are honoring the summer solstice today as the sun ascends to the highest point in the sky in the Northern Hemisphere.

But misconceptions about the summer solstice are common, according to astronomer Larry Ciupik at the Adler Planetarium and Astronomy Museum in Chicago.

So today, the first day of summer (and the longest day of the year), we examine four myths about the summer solstice.

Myth No. 1: The Seasons Change Because of the Earth's Distance From the Sun

Ciupik, who teaches college students at Indiana University Northwest, says one of the biggest misunderstandings about the summer solstice is that it is related to the Earth's distance from the sun. But the Earth rotates around the sun in an almost circular orbit, so the distance between sun and Earth doesn't change very much.

This year, Ciupik said, the Earth was closest to the sun Jan. 3rd and will be farthest away July 4.

"So the distance effect isn't the reason for the summer or season change; they change because the Earth is tilted," he said.

In other words, although the sun is farther away from the Earth during the summer solstice in the Northern Hemisphere, the Earth is tilted toward the sun, and the noon rays hit directly overhead the Tropic of Cancer. But during the winter, when the sun is somewhat closer, the Earth is tilted away from the sun.

The Latin translation of solstice means the sun, standing still; that's because it is about to start descending. After the solstice, the sun's altitude will decrease and the sunlight will become less direct.

Myth No. 2: Summer Solstice Is the Hottest Day of the Year

It's commonly assumed that because the sun's rays are hitting the Earth more directly, the summer solstice is the hottest day of the year. But it takes time for the Earth to heat up. So, in reality, the summer solstice brings the greatest amount of light to the Northern Hemisphere, not the greatest amount of heat.

"The hottest days are weeks later, on the average," Ciupik said. "The same thing is true in the winter. The winter solstice is Dec. 21; weeks later you get the coldest days."

Local conditions can cause exceptions to this general rule.