by MarkBour » Mon Dec 04, 2017 9:48 pm
mr.h8thsci wrote:My 8th science class would to know...what phase of the moon would you say is visible at about 5 seconds of the clip. We are having a tough time with the hole rotation of Earth vs. revolution of the moon. Thanks!
I think it is great that your class is using this and thinking of a subtle question about it!
You can see from the rotation of features on Earth relative to the terminator, that during the period of the video, the Sun rose over much of the Pacific, Japan, Australia, and much of Asia/India. I would make a really crude estimate that about 8 hours elapsed from the first frame to the last (perhaps one of the links has more exact data on this). As
Chris Peterson pointed out, then, the Moon did not go through very much of an orbit or change its phase as viewed from Earth much during that time. (If you watch a Moonrise one evening, then look at the Moon when it is 2/3 of the way across the sky -- about 8 hours later -- the change in phase is measurable, but very small.) During the video clip, for example, the Moon would have arisen from points of the Earth that rotated around the leftmost position visible on the Earth, so someone in Spain would have had a good evening of watching the Moon at the same time (if they had clear skies). And again, the phase of the Moon from different points of the Earth at a given time are also very very slightly different, but essentially the same.
Also, as
heehaw pointed out, the apparent motion of the Moon versus the Earth here is almost completely due to the motion of the spacecraft. Like when you are riding in a car and watch some bushes near the road versus a building farther away. The Earth passed the Moon in an effect called parallax. The Moon is nearer to the spacecraft than Earth (as one of the links says, 6% nearer). If you watch closely, you'll see that the Moon's apparent motion in the video is almost perfectly a straight line, not a curve, which one would see if it was actually orbiting the Earth very much.
But, I'm taking quite a while to get at what I think you were asking: What was the phase of the Moon from the Earth that night?
I think you're trying to "eyeball it" from the video, to work it out yourselves. Given that they passed each other from parallax and that Earth is almost exactly at a quarter phase from the spacecraft, I would guess that the Moon is pretty nearly overhead of Earth's sunrise terminator at this point in time. So I would guess that the Moon was about at 3rd quarter phase, as did
Wadsworth.
Of course the exact answer could be found by digging out an old calendar and looking at Dec. 16, 1992. Or, here:
https://stardate.org/nightsky/moon[quote="mr.h8thsci"]My 8th science class would to know...what phase of the moon would you say is visible at about 5 seconds of the clip. We are having a tough time with the hole rotation of Earth vs. revolution of the moon. Thanks![/quote]
I think it is great that your class is using this and thinking of a subtle question about it!
You can see from the rotation of features on Earth relative to the terminator, that during the period of the video, the Sun rose over much of the Pacific, Japan, Australia, and much of Asia/India. I would make a really crude estimate that about 8 hours elapsed from the first frame to the last (perhaps one of the links has more exact data on this). As [b]Chris Peterson[/b] pointed out, then, the Moon did not go through very much of an orbit or change its phase as viewed from Earth much during that time. (If you watch a Moonrise one evening, then look at the Moon when it is 2/3 of the way across the sky -- about 8 hours later -- the change in phase is measurable, but very small.) During the video clip, for example, the Moon would have arisen from points of the Earth that rotated around the leftmost position visible on the Earth, so someone in Spain would have had a good evening of watching the Moon at the same time (if they had clear skies). And again, the phase of the Moon from different points of the Earth at a given time are also very very slightly different, but essentially the same.
Also, as [b]heehaw[/b] pointed out, the apparent motion of the Moon versus the Earth here is almost completely due to the motion of the spacecraft. Like when you are riding in a car and watch some bushes near the road versus a building farther away. The Earth passed the Moon in an effect called parallax. The Moon is nearer to the spacecraft than Earth (as one of the links says, 6% nearer). If you watch closely, you'll see that the Moon's apparent motion in the video is almost perfectly a straight line, not a curve, which one would see if it was actually orbiting the Earth very much.
But, I'm taking quite a while to get at what I think you were asking: What was the phase of the Moon from the Earth that night?
I think you're trying to "eyeball it" from the video, to work it out yourselves. Given that they passed each other from parallax and that Earth is almost exactly at a quarter phase from the spacecraft, I would guess that the Moon is pretty nearly overhead of Earth's sunrise terminator at this point in time. So I would guess that the Moon was about at 3rd quarter phase, as did [b]Wadsworth[/b].
Of course the exact answer could be found by digging out an old calendar and looking at Dec. 16, 1992. Or, here: [url]https://stardate.org/nightsky/moon[/url]