Event Date: December 16th
Time: 5:30 PM
Brief
Let's pan the sky from the southwest, where we have looked the last two days at the Moon. Instead, while keeping the Moon in view at the right side, we are centered directly south. Therefore, I have included the meridian. On either side, is Uranus and Neptune just barely visible in a telescope, as the sky darkens. Uranus is further north of Neptune, as noticed using the celestial equator.
Seen below, are the two distant gas giants labeled, with the still-waxing crescent Moon on the far right, now setting about 3 hours after the Sun.
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click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.
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Detailed
Where the ecliptic crosses it not far east of the meridian, is the spot where our Sun is on the vernal equinox: entry one of this blog back on March 20th. Since then, the Sun has moved nearly 3/4 of the way along the ecliptic, with the December solstice later this week. When the Sun reaches ecliptic longitude 0º again this coming March for the next equinox, it will wash out both Uranus and Neptune, with the former nearly at conjunction at that time. Neptune will be a morning riser, yet way too dim to see until late into the spring. As for tonight, wait until darker skies to try to view any color for either planet, through large enough telescopes. While Uranus can be seen with a 4" telescope with a little greenish-blue, fainter Neptune requires an 8" to see it as a very tiny disc at high magnifications. A 10 or 12" telescope is recommended to gather more light and therefore, see more color. After all, Neptune's reflecting of blue light (and absorbing others) as a result of the Sun, needs to be gathered by a good size mirror or lens of the aforementioned size...minimum!
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