Planets appear to go backwards (retrograde) as the earth passes them in space.

click here to restart the animation below

Here's an animation of two planets showing that the apparent retrograde motion of the outer planet is an
illusion caused by the faster moving inner planet overtaking and passing the slower outer planet.

click here to restart the animation below

If observed from one night to the next, a planet appears to move from West to East against the background stars most of the time. Occasionally, however, the planet's motion will appear to reverse direction, and the planet will, for a short time, move from East to West against the background constellations. This reversal is known as retrograde motion, and is illustrated in the following animation.

Summer solstice: June 21st
Winter solstice: December 21st
Equinoxes: March 21st & September 23rd.
To an observer in the mid-latitudes of the northern hemisphere facing north, stars appear to make a complete circle around Polaris (North Star).
Blue Shift: object (e.g.: star) is getting closer to earth. Red Shift: object is getting further away (provides evidence universe is still expanding).

Red Shift
object further

Blue Shift
object closer

Equator always has 12 hours of day-light.
The lower the altitude of the sun, the longer the shadow it casts.

click here to restart the animation below

When the shadow is the longest on the windmill, the sun is in a position similar to C

The Coriolis Effect results from the earth's rotation. The Foucault Pendulum illustrates the Coriolis Effect, and so 'proves' the earth's rotation.
Notice how the ball appears to be going straight down (top), but the actual path was curved (bottom). This curving of objects due to Coriolis Effect proves the earth is rotating. Notice how the earth is rotating underneath the swinging ball but the ball is not rotating with the earth. If we were to trace the pendulum movement on the earth, it would look like the second image below. If the earth wasn't’t rotating we would expect a straight line.

Earth is closer to the sun in the winter.


The closer the planet is to the sun the higher it's velocity and the further the planet is from the sun, the slower its velocity.

The sun is one foci on an ellipse. There is nothing at the other foci.



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