Event Date: August 23rd
Time: 9:00 PM
Brief
I haven't talked about Neptune much this summer, although this is a good time to resume the focus. Today, the distant planet--over 2 billion miles away--is at opposition this evening; 180º separated from the Sun, which is of course the same as saying, maximum elongation. Shown below is the planet within the boundaries of Aquarius, about as high above the horizon as the Sun is below it. The stick figure of the water bearer shows, along with that of west-neighbor Capricornus where Neptune spent over a decade prior to its Aquarius stay.
Time: 9:00 PM
Brief
I haven't talked about Neptune much this summer, although this is a good time to resume the focus. Today, the distant planet--over 2 billion miles away--is at opposition this evening; 180º separated from the Sun, which is of course the same as saying, maximum elongation. Shown below is the planet within the boundaries of Aquarius, about as high above the horizon as the Sun is below it. The stick figure of the water bearer shows, along with that of west-neighbor Capricornus where Neptune spent over a decade prior to its Aquarius stay.
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| click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
Detailed
About four minutes before the Sun sets, more-southern Neptune rises; this is normal, considering that the Sun is still north of the equator and takes a little longer to sink towards the horizon. When oppositions happen close to the celestial equator, as we will see with Uranus a few weeks from now, the time of rise and set for the planet and Sun respectively usually has less of a gap. The reason for this, is because the declination of the Sun and planet are closer to being the same. There are times at the equinoxes that a planet's ecliptic latitude is a few degrees north of south, as is often the case of Mars for its oppositions. However, the "gas giants"--Jupiter through Neptune--have orbits that don't swing them quite as far as Mars.
Getting back to Neptune here, look at the star labeled that can help us find it a little more easily: although only 4th magnitude, Iota Aquarii is 3.2º apart from Neptune. Having moved from the eastern Capriocrnus stars seen nearby, we will rely on Aquarius' stars and fields for hopping to Neptune from other targets. This isn't too easily with Aquarius' brightest stars being hard to see. However, getting to know the star fields help, while Neptune's retrograde motion will bring it back towards Iota Aquarii by several arc-minutes over the next two months.
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