Tonight … don’t expect to see Neptune, even though (because!) it’s close to the rather wide waxing crescent moon. Neptune – eighth planet out from the sun and outermost of the major planets according to the International Astronomical Union – is the only major planet in our solar system that you absolutely can’t see with the unaided eye. The even-more-distant dwarf planet Pluto isn’t visible to the unaided eye, either, of course. On November 28, 2014, Neptune shines in front of the constellation Aquarius, and near the star Sigma Aquarii (chart of Aquarius below). Neptune is also close to the ecliptic – the path the planets follow in front of the constellations of the Zodiac. Because of the moonlit glare, you probably won’t see much of Aquarius tonight. What will you see? Only the moon shining in all its splendor. You can gaze at it and imagine Neptune nearby.
Although the moon and Neptune are close together on the sky’s dome tonight, they’re nowhere close in space. The moon resides about 1.2 light-seconds from Earth, whereas Neptune looms way out there at over four light-hours away. In other words, Neptune is over 12,000 times farther away than the moon in tonight’s sky.
Once the moon leaves the evening sky, starting the second week in December, Aquarius will easy to spot in a dark country sky. Then, if you’re armed with a telescope or powerful binoculars and a good sky chart, you might be able to glimpse Neptune.
For a stellar reference, learn how to star-hop to Sigma Aquarii, your guide star to Neptune. Neptune demands high-quality binoculars or a telescope, patience and a detailed star chart. Look for Neptune and the star Sigma Aquarii to take stage within the same binocular field.
Bottom line: On this November night – November 28, 2014 – use your mind’s eye to envision the solar system’s most distant major planet – Neptune – by tonight’s waxing crescent moon.