Skip Navigation
Button that takes you to the Dinosaur Floor page.Button that takes you to the Earth Floor page.Button that takes you to the Resource Room page.Button that takes you to the Teacher's Lounge page.Button that takes you to the Elevator page.
     

Image that says Orbital Changes.

Animation showing an orbital change of a planet around a star.What Is an Orbit?
Here we see a planet in an orbit around a star. The planet follows the same path over and over in a cycle. The time to complete one orbit is called the "period." The period of the Earth's orbit is defined as one year. Unless some other massive object comes nearby and disturbs the planet, it will continue in the same orbit forever.

This orbit is "stretched out" or elongated. (The technical term is "eccentric.") Thus, during part of the orbit, the planet is very close to the star, and during another part, the planet is very far from the star. The point of the orbit where the planet is closest to the star is called the "perihelion." The point where the planet is farthest from the star is called the "aphelion."

Several things are happening to the planet in the animation during its orbit. As the planet comes closer to the star, its surface gets warmer (indicated by the change in color), just like you get warmer when you move closer to a fire. For an orbit like that shown, the temperature changes on the surface of the planet would be huge! Also, notice that as the planet gets closer to the star, it moves faster because the pull of star's gravity on the planet becomes stronger.

Image showing a nearly circular orbit of planet around a star.Fortunately for us, in our Solar System the orbit shown above is typical of a comet or an asteroid, but not planets. Instead, the orbits of the planets, including the Earth, are nearly circular like the orbit shown to the right. For this reason, the distance of the planet is almost constant, so the speed of the planet is nearly constant, and, most important for us, the surface temperature remains nearly constant. (Note: The seasons on Earth are not caused by changes in the distance between the Sun and the Earth, but are due to the tilt of the Earth.

Back | Next

 

 


Image that says Dinosaur Floor.
Button that takes you to the Giant Impact page.
Button that takes you to the Super Nova page.
Button that takes you to the Disease page.
Button that takes you to the Volcanoes page.
Button that takes you to the Orbital Changes page.
Button that takes you to the Meet the Dinosaurs page.
Button that takes you to the Into the Future page.

Orbital Changes
The Ice Ages
Image of a star. What Is an Orbit?
The Shape of Earth's Orbit
The Tilt of Earth's Axis
The Wobble of Earth's Axis

 

 
             
     
Button that takes you to the Exploring the Environment home page.

Orbital Changes | The Ice Ages | What Is an Orbit? | The Shape of Earth's Orbit | The Tilt of Earth's Axis | The Wobble of Earth's Axis

Giant Impact | Super Nova | Disease | Volcanoes | Orbital Changes | Meet the Dinosaurs | Into the Future

  Image of a castle that links back to the MSESE home page.  
Button that takes you to the Dinosaur Floor page.Button that takes you to the Earth Floor page.Button that takes you to the Resource Room page.Button that takes you to the Teacher's Lounge page.Button that takes you to the Elevator page.

Site maintained by the ETE Team
Last updated on
April 28, 2005

Some images 2004 www.clipart.com

Privacy Statement and Copyright 1997-2004 by Wheeling Jesuit University/NASA-supported Classroom of the Future. All rights reserved.

Center for Educational Technologies, Circuit Board/Apple graphic logo, and COTF Classroom of the Future logo are registered trademarks of Wheeling Jesuit University.