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The Moon

One of the first objects mankind pointed telescopes at was the Moon.  I have spent hours and hours exploring the craters, Maria, and valleys of the Moon.  It has always provided surprises, and I know you'll enjoy your own journeys of discovery.  It's also a very, very bright object and can be seen easily through binoculars and telescopes.  Nearly at any magnification level greater than your eye's, you will be stunned by the details across the Lunar surface.


The current Moon phase looks like this:

The best introduction to the features of the Moon that I can think of is to begin the Astronomical League's "Lunar Club" program.  The program is challenging while still being within reach of people with binoculars and small telescopes.

More Moon information may be found by Clicking Here.


Here's a helpful photographic map with major features named.  It's large, but it prints out very well on a laser printer


As an amateur astronomer, you will inevitably be asked where the Apollo missions landed on the moon.  Here is a good map with individual Luna, Surveyor and Apollo  landing sites (or impact sites).  The picture is also "right clickable" as a high resolution graphic for saving on your computer.


Why Does the Moon Have Only One Face Towards the Earth All of The Time?  (or Does the Moon have a Dark Side?)
I'd like you to use a visual prop to help picture it this way... take two balls... a basketball and one tennis ball with a dime taped to one side of it.  The tennis ball will be the "Moon" and the bigger basketball will be the "Earth".
Put the Earth down on the floor and take your Moon and with your hands, make the Moon travel around the Earth in a careful, big circle.  OK?  Now try it again, but as you make the Moon 'orbit' the Earth, make sure that the dime is always facing the Earth.  As you do this a couple of times, notice that as the Moon is going around the Earth with the dime always facing it, the Moon is actually rotating, very slowly, around it's own axis one time for every one complete orbit around the Earth.
This is exactly what is happening with the real Earth - Moon system.   Relative to the Earth, the Moon makes one rotation every 29.5 days. This happens to also be the time it takes for the Moon to complete one orbital revolution around the Earth.  The result is that the Moon is turning very, very slowly around its axis and because of this match, it points just one familiar side towards the Earth.  This also means that while one Earth day takes about 24 hours from sunrise to sunrise, one day on the Moon takes... you guessed it... 29.5 Earth days!!
Interestingly, this is fairly common among moons of other planets and is called "Tidal Locking".
If you still have the tennis balls out on the floor, put a bright flashlight down on the floor about 6 feet away, turn it on pointed at the balls and turn off the other lights in the room.  Imagine that the flashlight is the Sun.  Now take your Moon ball, keep the dime always facing Earth, make a couple of orbits of Earth, but pay attention to what the shadows look like on the ball.  More importantly, imagine what the shadows would look like if you were teeny, tiny, and standing on the surface of your Earth looking out at the Moon as it orbited.  Can you see the half-moon and crescent shadows moving across the side of the moon facing Earth?  These represent the different phases of the Moon.
When the Moon is between the Earth and Sun, this is called a "New Moon" and we don't see the fully shadowed New Moon moon typically.  When the Earth is directly between the Moon and the Sun, You can picture a Full Moon because the flashlight illuminates the full face of the Moon in this orientation.  When the Moon is off to either side of the Earth, the shadows look more like "Half Moons".
This is probably a simpler example to actually do that to write about, but give it a try and see if this helps.  If not, let me know and I'll write more about it.



Introduction to the Night Sky - Part III

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