Shop Windows to the Universe

Please help support Windows to the Universe, and our activities to help Earth and space science teachers, with a tax-exempt donation today!
The seasons are a well-known example of a cycle.
Click on image for full size
Windows to the Universe original image

What is a Cycle?

Do you know what a cycle is? You may have studied them in school!

Cycles are events that repeat. Some cycles are very simple and other cycles are very complicated. One example of a cycle is the days of the week -- Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday, and then back to Monday! Can you think of any other cycles? How about the seasons? Summer, Fall, Winter and then Spring…over and over and over it goes!

Earth scientists study cycles a lot. One of the cycles they study is the water cycle. Other complicated cycles are called biogeochemical cycles.

Last modified June 29, 2005 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

The Winter 2009 issue of The Earth Scientist, focuses on Earth System science, including articles on student inquiry, differentiated instruction, geomorphic concepts, the rock cycle, and much more!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

What Causes the Seasons?

The Earth's orbit is in the shape of an ellipse (a stretched out circle), so that sometimes the Earth is closer to the Sun than at other times. Is this the cause of the seasons? You can imagine that if...more

Atmospheric Chemistry of Earth's Troposphere

When you think of chemistry, do you think about mixing colored liquids in test tubes and maybe making an explosion... or at least a nice puff of smoke? Did you know that a lot of chemistry happens in Earth's...more

Chemicals in Earth's Atmosphere

Most of the gas in Earth's atmosphere is nitrogen. About 4/5ths of the air is nitrogen. What about the other 1/5th? Almost all of it is oxygen, the stuff in the air we need to breathe. There are also very...more

Atmospheric Chemistry

When you think of chemistry, do you think about mixing colored liquids in test tubes and maybe making an explosion... or at least a nice puff of smoke? Did you know that a lot of chemistry happens in Earth's...more

A New Plan to Help Earth’s Changing Climate

Leaders from the countries of the world are heading to Copenhagen, Denmark in December 2009 to decide how the world will deal with climate change. They will make decisions about how to send less greenhouse...more

What Is Climate?

How do you know to pack your bathing suit and sunhat for a trip to a tropical island or pack warm sweaters and coats for a trip to Alaska? If you know a little about regional climates, then you know what...more

Earth's Greenhouse Gases

Only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases. But they have a huge effect on climate. There are several different types of greenhouse gases, but they all have something in...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA