Event Date: July 24th
Time: 8:24(.01) PM
Brief
The Moon may be already a little over 1/3rd illuminated and separated far enough from the Sun to be visible for much of the evening. Because of a declination difference of about 19º however with our star, the Moon sets only about 3 hours later. Despite slowly gaining ecliptic latitude back towards ascending node, the Moon is moving further south each day for the next few. During this time of year, evening western skies show us some of that azimuth's worst geometry of the year-- concerning apparition for the Moon and any planets if they were to be visible. We saw this with Mercury during its last swing east of the Sun, as it faded and sank quickly.
Here is the Moon and Sun at our star's official set time.
Time: 8:24(.01) PM
Brief
The Moon may be already a little over 1/3rd illuminated and separated far enough from the Sun to be visible for much of the evening. Because of a declination difference of about 19º however with our star, the Moon sets only about 3 hours later. Despite slowly gaining ecliptic latitude back towards ascending node, the Moon is moving further south each day for the next few. During this time of year, evening western skies show us some of that azimuth's worst geometry of the year-- concerning apparition for the Moon and any planets if they were to be visible. We saw this with Mercury during its last swing east of the Sun, as it faded and sank quickly.
Here is the Moon and Sun at our star's official set time.
Detailed
Despite only having a few good evening hours to see the Moon, don't forget to look for it also during the afternoon, when it rises shortly after 12 today. That gives us 8+ hours to see it before Sundown, including its terminator. The terminator is not the Arnold Schwarzenegger movie character; astronomically speaking, it marks the dark part of the Moon's disc where the Sun either rises or sets, for waxing and waning Moons respectively. If an individual [astronaut] was able to walk quickly enough to stay on the terminator on the Moon one minute after another, he or she would constantly see the Sun rising or setting.
Here is another zoom in of the fat, crescent Moon for this evening, with a field of view of 1º. Even if the software cannot provide the real image, it does well, providing a sample of the terminator for each phase.
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| click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
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