Retrograde motion of Mars, June to November, 2003

Who is this guy?Use SkyGazer or StarCal to find out!

The Four Seasons

Is the changing seasons caused by the change in the distance between the Sun and the Earth?

No. If it is, then – The northern and southern hemisphere should have

the same season, not opposite season like we have.

– We should experience real seasonal changes in Hawaii also.

– …

The Four Seasons: The Effect of the Tilt of Earth’s Rotation Axis

The Reasons for the Seasons on Earth

• The seasons on Earth are caused by the 23.5º tilt of its rotation axis, and its revolution around the Sun.

• Although the distance of the Earth to the Sun changes slightly as it orbits around the Sun, its effect is not big enough to cause the four seasons.

The Moon

The moon revolves around the earth with a period of about 29 ½ days ~ one month!

Facts about the Moon…• We see the moon changes its

appearances and position in the sky with approximately 30-day cycle.

• Unlike the stars, Moon can also be seen during the day.

• We also see that the Moon is always involved in eclipses, and

• Its position seems to be well correlated with the tide of the ocean.

• Understanding the motion of the Moon with respect to the Sun and the Earth will explain these phenomena.

The Face and Phases of the Moon

• The phase (how much and which side of the Moon is illuminated) of the Moon changes with about one month period…

• The face (the features on the surface of the Moon) does not change at all…

The Phase of the Moon

The phase of the Moon depends on the relative position between the Sun, the Earth, and the Moon…

Phases of the Moon

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Moon Rise/Set by Phase

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