Event Date: October 14th
Time: 6:45 AM
Time: 6:45 AM
Brief
Rising precisely 53 minutes before the Sun, during nautical twilight, is the very old (1%), waning gibbous Moon. At this point in its phase, our satellite hardly has any more time to wane, as it reaches new phase at 5:04 AM the next day. Between now and then, its separation from the Sun decreases quickly. Looking at this image, half an hour before the Sun begins to rise, the Moon is already 3º above the horizon, looking like a thin smiley face, shown in image two. 15 minutes later, while the sky is still barely dark enough to see it with the eye alone, the Moon is just short of 6º above the horizon, making it much easier to see over more hillsides, houses and trees.
The first image shows it at the time above zoomed out, while as mentioned above, the second image shows a 1º field of view for the zoom-in; this magnifies the Moon about 50 times. For the first, the ecliptic and celestial equator show, which I will talk more about in the detailed section.
Rising precisely 53 minutes before the Sun, during nautical twilight, is the very old (1%), waning gibbous Moon. At this point in its phase, our satellite hardly has any more time to wane, as it reaches new phase at 5:04 AM the next day. Between now and then, its separation from the Sun decreases quickly. Looking at this image, half an hour before the Sun begins to rise, the Moon is already 3º above the horizon, looking like a thin smiley face, shown in image two. 15 minutes later, while the sky is still barely dark enough to see it with the eye alone, the Moon is just short of 6º above the horizon, making it much easier to see over more hillsides, houses and trees.
The first image shows it at the time above zoomed out, while as mentioned above, the second image shows a 1º field of view for the zoom-in; this magnifies the Moon about 50 times. For the first, the ecliptic and celestial equator show, which I will talk more about in the detailed section.
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| click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
Detailed
As a result of very good geometry at this time of year for the morning eastern sky, we see in image two, the lit portion of the Moon slightly towards the bottom, as opposed to the side. As image one showed however, the Moon is a little further south of the ecliptic by more than 4º. Therefore, since the azimuth of the Moon puts it a little south of east, we see the lit portion of the Moon representing where the Sun is hitting it. Of course, alot more of the Moon than what we see is lit, yet from our perspective, that lit portion is turned away from us.
As for the equator and ecliptic, we also see that over the last few days, the Moon has been north of the Sun and therefore, rising well before it even while being the last few days of a waning crescent. As we approach new Moon however, the Moon and Sun's declination difference quickly changes. As a result of the Moon and Sun having different ecliptic latitudes when new, the Moon will pass south of the Sun. It is because of this that even if called new, there may still be a very slight lit portion, that we will not see of course because of the Sun's glare. Enjoy the Moon this morning before we lose it for a few days to the Sun's glare. It will be more visible again as a waxing crescent starting about October 17th.
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