NOW FOR SOME IMPORTANT (AND INTERESTING) INFORMATION TO MAKE SURE YOU HAVE IN YOUR BOOK NOTES ABOUT PHASES

OF THE MOON

You only need to make sure you have written down what is in bold and underlined

Intro

The moon is almost 385,000 km away from the Earth on average

The moon is in motion – it revolves around the Earth as Earth revolves around the sun

Phases of the moon, eclipses and tides are caused by how the sun, moon and Earth are positioned.

Slide 1

Motion of the Moon It takes the same amount of time for

the moon to rotate on its axis as it does to revolve around the Earth (27.3 days) so moon year = moon day

This is the reason why the Earth only sees one side of the moon – in order to see the other side you need to get on a space ship and go around the moon!

The Near Side ALWAYS faces Earth and the Far Side ALWAYS faces away from the Earth

Slide 2

Moon Rotating and Revolving

http://www.das.uchile.cl/~mhamuy/moon.html

Slide 3

Phases of the Moon Moon shines because it reflects sunlight Phases: different shapes of the moon

seen by earth

www.moonconnection.com

Slide 3

What causes phases? Phases caused by relative positions of

Earth, moon and sun As moon revolves around Earth different

parts of moon are lit Phase we see depends on how much of

the sunlit half of the moon is facing the Earth

http://www.das.uchile.cl/

Slide 4

Exploring the Phases of the Moon

The lit part of the moon always points towards the sun.

When waxing: light is on the right

When waning: shadow is on the right (light on left)

http://www.astro.virginia.edu

Slide 6

Can you identify the phase?

Waxing Gibbous

Full

Waning Crescent

Waning Gibbous

New

Last (3rd) Quarter

First Quarter

Waxing Crescent

Slide 7

The Cycle of Phases

There are 29.5 days from a new moon to the next new moon

During these 29.5 days the Earth sees more and more of the lighted half of the moon until the full moon and then less and less of the lighted half of the moon

Slide 8

Reason for Moon Phase Cycle Length – why 29.5 days and not 27.3 days

This is showing the cycle from full moon to the next full moon

Slide 9

The moon rise, moon set The time of the moon rising and setting depends

on its phase Rises in the East and sets in the West – due to

Earth’s rotation Moon rises about 50 min later each day of the

moon phase cycle (~ 25 to 75 mins)

Phase Rise Time Midpoint in sky Set Time

New Sunrise Noon Sunset

1st quarter Noon Sunset Midnight

Full Sunset Midnight Sunrise

3rd quarter Midnight Sunrise Noonhttp://aa.usno.navy.mil/cgi-bin/aa_rstablew.pl

Slide 10