UK gets a full moon after the USA, why?

[alex05]

Why does the United Kingdom get a full moon a day after the USA when the UK is 6 hours ahead of the USA?<br /><br />Sincerely,<br />alex

 

[igorsboss]

<font color="yellow">Why does the United Kingdom get a full moon a day after the USA when the UK is 6 hours ahead of the USA?</font><br /><br />The full moon is an instantaneous event, not a day-long event. It can be calculated very precicely, to the nearest second (but not by me!)<br /><br />It happens when the Sun, Earth, and Moon are at syzygy, with the Earth in the middle. Syzygy means that the three objects are most nearly lined up.<br /><br />Suppose the instant of the Full Moon happens at 03:00 Zulu. This is 21:00 EST, on the previous day.<br /><br />So, the local calendars in the UK say that the full moon happens a day later than the full moon happens in the USA.<br /><br />The problem isn't the moon; you're using two different clocks!<br /><br />As a fortune cookie once told me, "A man with one watch knows what time it is, a man with two never does."

 

[alex05]

AHHH! Thank you so much!<br /> <br />I just found this site that lists the exact times of the full moons.<br /><br />http://aa.usno.navy.mil/data/docs/MoonPhase.html#y2005<br />It shows the next full moon as July 21 at 11:00 hours. The time is Universal Time (also known as Greenwich Mean Time), which is usually about 5 hours ahead of Eastern Standard Time. <br /><br />So, the exact time of the full moon in New York City will be July 21st at 6am. <br /><br />And in this case, the USA calendars areshowing it as July 21st.<br /><br />I just looked at all of the full moon dates for 2005 and the UK is only ahead of the USA when the Full moon exact instant happens in Universal Time before 5am.<br /><br />Thanks,<br />alex

 

[alex05]

You said:<br />The full moon is an instantaneous event, not a day-long event. It can be calculated very precicely, to the nearest second.<br /><br />My new Question: Is the full moon really full everywhere on earth at this calculated moment? Or do we just report that as the official full moon and the experience from different parts of the earth changes?<br /><br />Your answer:<br />It happens when the Sun, Earth, and Moon are at syzygy, with the Earth in the middle. Syzygy means that the three objects are most nearly lined up. <br /><br />My new Question:<br />I don't get this. Shouldn't it be SUN = /> MOON => Then the earth if the moon is full. If the earth was in the middle, wouldn't we experience that as a NEW MOON?<br /><br />Thanks,<br />alex

 

[lunatio_gordin]

no. If the moon were between the sun and the earth, then the sunlight would hit the far side of the moon. THAT is a new moon.

 

[igorsboss]

Time to head to the lab...<br /><br />Obtain the following:<br />1) A basketball-sized ball. This is the Earth.<br />2) A tennis-ball sized ball. This is the Moon.<br />3) A lamp with the lampshade removed. This is the Sun.<br /><br />Now, turn the light on in an otherwise dark room.<br /><br />Observe the shadows for yourself. Use this to explain the phases of the moon.<br />

 

[alex05]

Cool. I will do this

 

[alex05]

I did this experiment and it really made it clear to me.<br /><br />Thank you so much.

 

[igorsboss]

Excellent! Now for a test question...<br /><br />You already know that the Moon orbits the Earth, and the Earth orbits the Sun.<br /><br />In which direction is the Moon actually moving in it's orbit? From East to West, or West to East?<br /><br />To answer this, observe the Moon's position in the sky (by eye) for several nights.<br /><br />Others: Please don't post the answer even if you know it.