Click the "Play Fast" button in the lower left corner to make the planets move. They will advance at a simulated rate of one week per second.
This animation shows the orbital motions of Earth and Mars.
Click the "Play Fast" button in the lower left corner to make the planets move. They will advance at a simulated rate of one week per second.
(Note: If you cannot see the animation below, or it is not working properly, you may need to download the latest Flash player.)
The other buttons make the planets move faster or slower, move backwards, or stop. The date in the simulation is shown above the buttons.
In the upper left corner is a simulated view of Mars as seen from Earth through a telescope. This simulated view shows the relative size of Mars at different times; it is not an "actual view" of Mars. For example, it does not show Mars rotating on its axis or changes in the Martian seasons.
Beneath the "telescope view or Mars" is a readout of the distance between Earth and Mars. Astronomers call the closest approach (when Earth "laps" Mars on the "inside lane") between Earth and Mars an "opposition". Notice how the apparent size of Mars varies between successive oppositions. This variation is primarily a result of the ellipticity (non-circularness) of Mars's orbit. The distance between Earth and Mars at opposition can be less than 55 million kilometers, or more than 100 million kilometers, depending on where Mars is along its elliptical orbit when opposition occurs. The oppositon in August 2003 was an especially close one. At that time, Earth and Mars were closer together than they had been in thousands of years!
The red dot is Mars. Earth is blue, and the Sun is yellow. The locations of the planets are shown to scale, but their sizes are not (the planets are actually much, much smaller than the Sun).
This animation shows how Earth and Mars move around the Sun in their orbits.
Click the "Play Fast" button in the lower left corner to make the planets move. For every second that goes by, the planets will move ahead one week's worth of time.
(Note: If you cannot see the animation below, or it is not working properly, you may need to download the latest Flash player.)
The other buttons make the planets move faster or slower, move backwards, or stop. The date in this simulation is shown above the buttons.
The "telescope view" in the upper left corner shows how big Mars looks from Earth through a telescope at a given time. The view only shows the size of Mars as viewed from Earth. It does not show how Mars changes in other ways over time, such as Mars spinning on its axis or the changing seasons on Mars.
Beneath the "telescope view" is a readout of the distance between Earth and Mars. Each time Earth passes close to Mars the event is called an "opposition". Notice how the size of Mars as seen through the telescope is not the same at every opposition. The orbit of Mars is not a circle; it is more of an oval in shape. Because an opposition can happen when Mars is at different points in its orbit, the distance at opposition changes, and so does the size of Mars as viewed from Earth. During the opposition in August 2003, Earth and Mars were closer together than they had been in thousands of years!
The red dot is Mars. Earth is blue, and the Sun is yellow. The locations of the planets are shown to scale, but their sizes are not (the planets are actually much, much smaller than the Sun).
This animation shows how Earth and Mars move around the Sun in their orbits.
Click the "Play Fast" button in the lower left corner to make the planets move. For every second that passes, the planets will move as far as they go in one week.
(Note: If you cannot see the animation below, or it is not working properly, you may need to download the latest Flash player.)
The other buttons make the planets move faster or slower, move backwards, or stop. The "pretend" date is shown above the buttons.
The circle in the upper left corner shows how big Mars looks through a telescope from Earth. The text under the telescope view shows how far apart Earth and Mars are.
The red dot is Mars. Earth is blue, and the Sun is yellow. This animation shows where the planets really are. However, the sizes of the planets are much too big in this view than they really should be. If we showed the planets at their "real" sizes, they would be very tiny dots.
Page created July 29, 2003 by Randy Russell.
Last modified February 18, 2004 by Randy Russell.
The source of this material is Windows to the Universe, at http://www.windows.ucar.edu/ at the University Corporation for Atmospheric Research (UCAR). © The Regents of the University of Michigan. Windows to the Universe® is a registered trademark of UCAR. All Rights Reserved. Site policies and disclaimer