The month of September affords stargazers a last chance to see the Milky Way and all its attendant splendors. The rich constellations of Scorpius and Sagittarius are setting for the year, moving a little westward each night, but the lengthening nights keep these stars accessible for a little longer, at least for observers in the northern hemisphere. Southern observers still enjoy the thickest part of the Milky Way almost overhead. In the east, the relatively star-poor constellations of Pegasus, Capricornus, and Piscis Austrinus are moving into view. Observers with very dark sky get the chance this month to see the zodiacal light, a faint wedge of white sunlight reflected from fine dust in the inner solar system. Also this month, low in the southwestern sky at sunset, Jupiter slowly fades from view while Saturn still hangs on, its rings casting dramatic shadows on the disk of the planet. Mercury makes its best showing of the year in the eastern sky before dawn. And the Sun crosses the celestial equator heading south, marking a change of seasons. Here’s what to see in the night sky this month…
4 Sept. Neptune reaches opposition today. This blue-green ice giant, the most distance major planet from the Sun in our solar system, shines at magnitude 7.8 and spans an apparent diameter of 2.4″. Its tiny disk is visible in the constellation Aquarius less than 1º east-southeast of the orange 4th magnitude star Hydor (λ Aquarii). While the planet is plenty bright enough to see with a telescope, or even binoculars, resolving its disk requires some magnification, at least 75x to 100x. The planet’s disk gets larger with more magnification while the images of the stars do not. Visually, the planet has a very pale blue-green color [Read more…] about The Sky This Month – September 2017
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