Sunday is the summer solstice, marking the start of astronomical summer north of the equator. It’s the opposite in the Southern Hemisphere, where it is the shortest day of the year and winter will start.

Understanding the Solstice

The word “solstice” comes from the Latin words “sol,” for sun, and “stitium,” which can mean “pause” or “stop.” The summer solstice is the end of the sun’s annual march higher in the sky, when it makes its longest, highest arc.

As the Earth travels around the sun, it does so at an angle, making the sun’s warmth and light fall unequally on the northern and southern halves of the planet for most of the year. The solstices mark the times when the Earth is tipped most extremely either toward or away from the sun.

Seasonal Changes

The Northern Hemisphere’s fall — or autumnal — equinox can land between Sept. 21 and 24, depending on the year. Its spring — or vernal — equinox can land between March 19 and 21. The exact time of the equinox is the moment the sun is directly overhead at the equator.

Meteorologists break down the year into three-month seasons based on annual temperature cycles. By that calendar, spring starts on March 1, summer on June 1, fall on Sept. 1 and winter on Dec. 1.

Original reporting: NBC4 Los Angeles — read the source article.