More recently, this thought became fixed to the time of the spring equinox. The underlying assumption relating to standing eggs on end is that there must exist some special gravitational balance. There are many forces acting on an egg when you try to stand it on end on a flat surface.
Some people think that the gravitational pull of the Sun becomes balanced with that of the Earth to allow for this phenomenon to occur. However, the Moon exerts a much stronger gravitational effect on the Earth than the Sun, dominating the ebb and flow of the ocean tides.
The Moon's effects are different at each of the equinoxes however. The most dominant force of gravity on a standing egg is the one between the Earth and the egg itself. This is determined by the weight of the egg and the force pulling the egg to the counter top. If you want to prove this to yourself, take a fresh, uncooked egg and hold it with the larger end resting on a table or counter top. Wait for the fluid content of the egg to settle, then carefully test the balance. Be patient as you find the point where you can ever so gently let it go to remain standing on end.
Please Contact Us. Please try another search. Multiple locations were found. Please select one of the following:. Location Help. News Headlines. Customize Your Weather. Privacy Policy. Why Do We Have Seasons? Current Hazards. Local Radar. Rivers and Lakes. Climate and Past Weather. Why Do We have Seasons? Weather Story. Well, yes, in a sense, it does, just not the way people expect. Earth's orbit around the Sun is only slightly elliptical. The difference between its closest point to the Sun and the most distant is a little more than three percent.
That isn't enough to cause huge temperature swings. It translates to a difference of a few degrees Celsius on average. The temperature difference between summer and winter is a lot more than that.
So, closeness doesn't make as much of a difference as the amount of sunlight the planet receives. That's why just simply assuming that Earth is closer during one part of the year than another is wrong. The reasons for our seasons are easy to understand with a good mental image of our planet's tilt and its orbit around the Sun. Actively scan device characteristics for identification. Use precise geolocation data.
Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products.
List of Partners vendors. Share Flipboard Email. John P. Millis, Ph. Professor of Physics and Astronomy. Updated February 04, Note that there is no significant difference in the distance of the sun to the Northern and Southern Hemispheres.
The difference is due to direct and indirect solar radiation. The hemisphere that is pointed toward the sun receives more direct solar radiation, thus it is warmer.
Ask: Is the sun more direct, or bright, for the person in the Northern Hemisphere or the Southern Hemisphere? Southern Hemisphere Which person do you think feels warmer temperatures? Use guided inquiry to help students investigate the role of axis and tilt in the sun-Earth relationship. Tape a black circle to the wall at that location to help students keep the axis pointed in one direction. Next, ask the Earth to resume orbiting the sun, while keeping the North Pole pointed at the black circle.
Remind students to keep the sun stationary and pointed at Earth. Explain to students that the Earth's tilt does not change significantly over the course of a year, but does shift gradually over millennia. Have students stop the Earth after one-half of an orbit so that it is opposite of where it started.
It should be night for them if the Earth has orbited correctly, so the student will have to spin the Earth. Finally, ask groups to move the Earth half an orbit around the sun again, making sure to keep the North Pole pointed at the black circle. Make sure the sun does not move. Also, ensure as the Earth orbits the sun, the axis does not change orientation and continues pointing to the black circle.
Have students make a math connection. Have the rest of the students sit on the floor in a small area near the center of the classroom but facing the sun. Ask students to imagine that the floor is the Northern Hemisphere of the Earth. In the winter, the North Pole of the Earth is pointing away from the sun, so the sun appears farther south in the sky to us.
Have the student hold the sun closer to the floor. Have the rest of the class place their hands close to the floor and point toward the sun. Ask: Do your finger and the floor form a large or small angle? Then have the student holding the sun hold it up as high as he or she can. Have the rest of the class keep their hands close to the floor and again point to the sun. Ask: Is the angle you have formed with your finger and floor larger or smaller?
Ask: What season does this represent? Point out to students that the seasons are opposite for people on the top north of the Earth and on the bottom south of the Earth. Ask students to orally explain how the interaction between the sun and Earth affects seasons here on Earth, and what happens with the sun's rays during the different seasons. Encourage them to use vocabulary terms axis, tilt, direct sunlight, and indirect sunlight in their responses.
Explain to students that every planet in our solar system has seasons. But the seasons that occur on other planets are extremely different from the traditional spring, summer, autumn, and winter that we experience on Earth. Which would cause more extreme seasons—a smaller or larger tilt? Which would cause more extreme seasons—being closer or farther away?
Then have them read a list from NASA about the length of seasons on other planets in our solar system. One common misconception that students have about seasons is that seasons are due to how close or far the Earth is to the sun.
When the Northern Hemisphere of the Earth is leaning toward the sun, it receives direct sunlight. The warmth of direct rays causes spring and then summer in that part of the globe.
When the Northern Hemisphere of the Earth is leaning away from the sun, it receives more indirect sunlight. The cooling effects of more indirect sunlight cause autumn and winter. Also called the spring equinox. December 22 in the Northern Hemisphere, June 22 in the Southern Hemisphere longest night of the year and the beginning of winter.
For advanced students, introduce the concepts of the winter solstice, summer solstice, autumnal equinox, and vernal equinox. Have them make connections between the hands-on activity and these special days that correspond to different points in the Earth's orbit. In Step 4, address any student misconceptions about direct versus indirect sunlight. Dim the lights.
Adjust a small flashlight to its most concentrated beam and shine the light on dark paper or a wall. Explain that this is similar to concentrated, direct sunlight during summer months. Then adjust the flashlight to the wide beam and describe it as dispersed, or indirect sunlight during winter months. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
0コメント