Neptune is in conjunction with the Sun today and is also at its furthest from the Earth. As seen from our vantage point, it appears on the other side of the Sun from us and currently isn’t visible.
Neptune is the eighth and most distant planet from the Sun. It is the smallest of the gas giants and although it was discovered in 1846, very little was known about it until the Voyager 2 space probe made the first (and so far only) fly-by of the planet in 1989. As it takes Neptune nearly 165 years to orbit the Sun, it’s barely completed just one orbit since its discovery.
(Click on the image to enlarge.)
Image courtesy of NASA/JPL, taken by Voyager 2.
00:48 UT – The first quarter Moon passes Aldebaran. (Taurus, evening sky.)
12:15 UT – Neptune is in conjunction with the Sun. (Neptune: magnitude 8.0, diameter 2.2”. Aquarius, not visible. See image above.)
21:28 UT – Neptune is at its farthest distance from the Earth – 30.957 AU (Magnitude 8.0, diameter 2.2”. Aquarius, not visible. See image above.)
Learn more about every upcoming astronomical event in 2015 An Astronomical Year (Kindle eBook) and The Astronomical Almanac (2015-2019) (Kindle eBook) and The Astronomical Almanac (2015-2019) (Paperback Edition).
The Amateur Astronomer’s Notebook allows astronomers to log 150 observing sessions and includes an appendix of hundreds of suggested deep sky objects.