Astronomy Unit 4, Section 2 Lunar Orbit

Natural Satellites Our Moon The Orbit of the Moon Vocab Words for “The Orbit of the Moon” 1st Quarter 3rd Quarter New Moon Full Moon Waxing Waning Synchronous Orbit Near Side Far Side Lunar Eclipse Solar Eclipse

Natural Satellites The Orbit of the Moon The moon revolves around the earth every 29.5 days. The moon rotates around itself every 29.5 days as well! This means the moon’s orbit is synchronous A Synchronous Orbit is when the period of revolution is equal to the period of rotation. The moon rotates at the same exact pace that is revolves at!

Natural Satellites The Orbit of the Moon The Synchronous orbit of the Moon causes the moon to have a Near Side and a Far Side. The Near Side of the Moon is the side of the moon that ALWAYS faces the earth. The Far Side of the Moon is the side of the moon that NEVER faces the earth. In 1959 the Russian Mission, Luna 3 (an unmanned space probe) photographed it. This is the first time people saw pictures of the Far Side. It wasn’t until 1968 that people saw it first hand. Apollo 8 was able to orbit the moon and view the far side. Astronauts Frank Borman, Jim Lovell and William Anders were able to see it.

Near Side on the Left and Far Side on the Right Natural Satellites Near Side on the Left and Far Side on the Right

Natural Satellites Note the differences between the Near Side and Far Side This is why scientists believe the Earth has had some impact on the Formation of the Moon.

Natural Satellites The Orbit of the Moon As the moon revolves around the earth it looks different in the sky each night. The different appearances of the moon in the night sky are called the Moon Phases. The moon is ALWAYS 50% lit up from the sun. It isn’t always the lit up side that is facing the earth. What we see at night (the different phases) are combination of the lit up portion of the moon and side of the moon facing the earth.

Natural Satellites

Natural Satellites The Moon goes through 8 distinct phases during each of its revolutions. New Moon Waxing Crescent 1st Quarter Waxing Gibbous Full Moon Waning Gibbous 3rd Quarter Waning Crescent

Natural Satellites

Natural Satellites New Moon is when none of the lit up portion of the moon is facing the earth. The moon appears completely dark in the night sky from earth. Full Moon is when all of the lit portion of the moon is facing the earth. The moon appears completely bright in the night sky from earth.

Natural Satellites The Waxing phases are the growing phases of the moon. When the moon goes from new moon to full moon The Waning phases are the shrinking phases of the moon. When the moon goes from full moon back down to new moon

Natural Satellites The Orbit of the Moon The moon’s orbit is tilted 5 degrees to the earth’s orbit.

Natural Satellites The Orbit of the Moon This tilted orbit means that solar eclipses and lunar eclipses will NOT occur each month. A Solar Eclipse is when the moon comes right in between the earth and sun and casts its shadow upon the Earth. The Moon should be New Moon phase at this point. A Lunar Eclipse is when Earth falls directly in between the sun and the moon and casts its shadow upon the moon. The Moon should be in Full Moon phase at this point.

Natural Satellites Solar Eclipse Position of Sun, Moon & Earth View from Earth Total Solar Eclipse

Natural Satellites Lunar Eclipse View from Earth Total Lunar Eclipse Position of Sun, Moon & Earth