Phases of the Moon and Planets

AST 115-999

Lab Report 1

Phases of the Moon and Planets

Gates Bartz

Purpose:

In this lab we explored the phases of the moon, where the moon appears in the sky at each phase, the rotation of the moon, and the phases of the other planets as seen from Earth.

Part 1:

In part one we used a model of the Earth, Sun, and Moon. The Earth was the stationary camera used to take the pictures below, the Sun was a light placed a few feet away, and the moon was a baseball-sized Styrofoam ball. Holding the Styrofoam ball at arm’s length, you would rotate counterclockwise and take pictures at eight different points (shown on Fig 1) displaying the simulated phases of the moon. The pictures below display my observations.

 

So as we observed, position 1 on figure 1 is a new moon, 2 is a waxing crescent, 3 is the first quarter, 4 is a waxing gibbous, 5 is a full moon, 6 is a waning gibbous, 7 is the third quarter, 8 is a waning crescent, and then the cycle begins again.

As predicted, the ball appears to undergo the same phases as our moon does in the sky. Based on these observations, a lunar eclipse would occur during a full moon at the time the Earth comes between the Sun and moon, and a solar eclipse would occur during the time that the moon is new and comes between the Earth and Sun.

Part 2:

In part two we used Figure 1 and a small dial to determine at what time the moon would rise and set during each phase. If you point the East end of the dial at the 1^st quarter moon, for example, then your meridian is at noon, when it rises. By the time you have spun the dial 180 degrees from that starting position, your West is pointed at the 1^st quarter, and your meridian is at midnight, because that is when it sets. This is how you would find the rise and set of each phase of moon.

 

Case in point, when the moon is new it rises at sunrise and sets at sunset, the full moon rises at sunset and sets at sunrise, and the 3rd quarter moon rises at midnight and sets at noon. 

Part 3:

Part three required us to use a model of the Earth and moon. Using a stationary object as the Earth, you find a distinguishing mark on the foam ball (Moon) and looking down from above (as if on the North Pole) you keep the mark facing the Earth.

 

The result of this is that we observe the moon rotating counter clockwise, much like it orbits the Earth counter clockwise. Of course, this side that we don’t see (the “hidden” side) is not always dark, it is just the reverse of what we see from Earth. For instance, when the moon is full for us, the hidden side is dark, but when the moon is new for us, the hidden side is lit.

            The second half of part three required us to repeat the exercise, but instead point the mark at the sun. From this we can see that the moon does not have a spin. It may wobble some but it does not spin in this example.

 

            As we know we constantly see the same features of the moon, so the moon is always facing the Earth as it spins and orbits counter clockwise.

Part 4:

Part four is also in two halves where we repeat what we did in part one, only as a planet orbiting the sun instead of the moon orbiting the Earth. The two halves, are that we do this from inside where the Earth’ orbit would be (the “inferior” planets, Mercury and Venus), and again from outside where the Earth’s orbit would be (the “superior” planets, Mars, Jupiter, Saturn, Uranus, and Neptune).

 

Inside the Earth’s orbit, a planet appears to go through phases similar to that of the moon but in reverse order. Outside the Earth’s orbit, a planet appears to only have a full and gibbous phase.