Understanding Moon Phases: Examples & Visualization

[chod]

I feel as though I have a good understanding of the movements of the moon, sun, planets and any other bodies out there, but there is still one thing that has been giving me trouble. My problem is finding out the phase of the moon given its position and the suns position in the sky. Can someone help me try to understand a way to visualize it? Here are some examples:

1) Moon is east of the Sun in the sky.
2) The Sun is located at the vernal equinox and the moon is at the autumnal
equinox.
3) A lunar eclipse occurred about one week ago.

 

[russ_watters]

Here's a recent thread on the subject: https://www.physicsforums.com/showthread.php?t=441518

However, the best way to visualize the phases is with a table lamp and some fruit!

However, however, I'm not sure what the equinoxes really have to do with the phases and the wording doesn't make much sense to me: the equinox has to do with the tilt of the Earth with respect to the Sun. It doesn't have anything to do with where the moon is. Perhaps equinox isn't the word you are looking for?

 

[chod]

I think it means that the moon will be full as they are separated by 180 degrees (if the nodes were aligned then it would be a lunar eclipse).

Thanks for the thread, I'll check it out

 

[Philosophaie]

The moon travels from West to the East. Having a Declination +/- 24degrees maximum/minimum somewhere above or below the Ecliptic. When the Declination is graphed with the Right Ascension it creates a sinusoid wth a peroid about 27 days.

http://en.wikipedia.org/wiki/Moon

 

[pmacias]

I can understand your confusion about determining the phase of the moon based on its position in the sky and the sun's position. Visualizing the moon's phase can be tricky, but there are a few key concepts that can help you understand it better.

Firstly, it's important to remember that the moon's phases are a result of its position relative to the sun and Earth. The moon's orbit around Earth causes it to appear to change shape as it reflects sunlight. This changing appearance is what we refer to as the moon's phases.

Now, let's look at the examples you provided:

1) When the moon is east of the sun in the sky, it is in its waxing phase. This means that the illuminated portion of the moon is increasing, and it will eventually reach a full moon phase.

2) The vernal equinox and autumnal equinox are important dates in the Earth's orbit around the sun. During these times, the sun's position in the sky is directly above the Earth's equator, causing equal amounts of daylight and darkness. In this scenario, the moon would be in its first quarter phase, meaning that half of the moon's face is illuminated and the other half is in shadow.

3) A lunar eclipse occurs when the moon passes through Earth's shadow. This can only happen during a full moon phase. So, if a lunar eclipse occurred about one week ago, it means that the moon was in its full moon phase at that time.

To help visualize these concepts, I recommend using a moon phase calendar or app. These tools show the moon's phase for a specific date and can help you better understand the relationship between the moon, sun, and Earth.

I hope this helps clarify the concept of moon phases for you. Remember, the key is to understand the moon's position relative to the sun and Earth. Keep exploring and learning, and you will continue to deepen your understanding of our amazing universe.