Today, the planet Earth in its orbit swings in between the sun and Neptune, the eighth planet outward from the sun. At this juncture, Neptune is said to be at opposition – opposite the sun in Earth’s sky. At opposition, Neptune rises in the east at sunset, climbs highest up for the night at midnight and sets in the west at sunrise.
Opposition is a special event. Wherever the Earth passes in between the sun and an outer planet, Earth comes closest to that planet for the year, and that planet, in turn, shines most brightly in our sky. Even at opposition, however, Neptune is not all that close and it’s not all that bright.
In fact, Neptune is the only major solar sytem planet that’s absolutely not visible to the unaided eye. This world is about five times fainter than the dimmest star that you can see on an inky black night. You’ll need binoculars and a detailed sky chart to see Neptune in front of the constellation Aquarius, and even at that, it’ll only look like a faint star.
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