Ever wonder why the northern and summer hemispheres have opposite seasons? Or why the longest day of the year is considered the start of summer? Whether you are just learning when to wear a winter coat, or are studying high school physics, there is probably something new for you to discover about the Earth's four seasons at today's website picks.
For elementary students, Enchanted Learning defines the terms solstice and equinox, and explains why we have four seasons. To complete the topic, there are variety of printable worksheets including an Earth's Seasons Quiz, a Seasons Word Pieces Puzzle, and a Label Me! Four Seasons Printout. Related topics, such as the Seasons Theme Pages (chock full of craft ideas) and The Planets, are just a click away.
With illustrations and animations, this online exhibit from the Liverpool Museums explains how the tilt of the Earth's axis causes the Earth's four seasons, and how a sundial works. Don't miss the SunTracker, an applet that illustrates the sun's path on any day, in any location. "Along the way there are quiz questions to answer, experiments to try and a sundial to make, so there's plenty to do. Words marked in red are glossary words. Click on them to see their meaning."
"The Earth spins on a tilted axis about once every 24 hours to create what we know as day and night. This axis is an invisible line through the center of the Earth. The northern point is the North Pole and the southern point is the South Pole." Best clicks at the Kids Science News Network (KSNN) site for grades K-2, are the activities page (two classroom projects about seasons) and an animated video about why the weather changes from one season to the next.
For high school and college students, retired NASA physicist David Stern explains the earth's orbit around the sun, why we have seasons, and answers lots of related questions. "If June 21 is the day when we receive the most sunshine, why is it regarded as the beginning of summer and not its peak? And similarly, why is December 21, the day of least sunshine, the beginning of winter and not mid-winter day?"
It is a common misconception that the seasons are caused by the Earth's changing distance to the sun, as it travels in an elliptical orbit around it. Visit Windows to the Universe to learn why this is not so. "You can imagine that if the seasons were caused by the Earth's orbit, people in the northern hemisphere and people in the southern hemisphere would have the same seasons. For example, if winter occurred because the Earth was far away from the Sun, everyplace on the Earth would be cold at the same time."