How about embarking on a rewarding challenge by trying to find and observe a pair of odd-colored worlds in the dark depths of the Solar System? Most planets are warm shades of soft pastels from yellow to tan, beige, and peach, but Uranus and Neptune are in the cool class of pastels, the blues. Both planets may be too far away and dim to observe with the unaided eye, but given a clear, moonless night preferably away from bright city lights they are both easy to locate and follow with the finder charts that follow this article.
Uranus (magnitude +5.6) and Neptune (magnitude +7.8) are dim because they orbit the Sun at a distance of 1.8 and 2.7 billion miles, respectively. In the dim depths of the outer Solar System, daytime sunlight is no brighter than a clear evening sky on Earth shortly after sunset. Both planets are about four times larger than Earth, slightly over 30,000 miles in diameter, and have thick atmospheres that are completely cloudy. The small amount of methane (3%) in Neptune’s atmosphere absorbs the red component of sunlight and scatters the blue creating a soft bluish hue. Uranus does not appear as blue because it has a little less methane (2%) and unlike Neptune it has a ruddy haze which shifts its color towards the green giving it a turquoise hue. These colors are obvious whenever they are near stars of contrasting colors.
Uranus is at opposition on November 25 in Taurus between the beautiful Pleiades and Hyades star clusters. It will be easy to locate among the brighter stars very high up above the worst of the atmospheric turbulence. Neptune is at opposition on September 25 in Pisces below the Circlet and a bit more challenging, but Saturn is not far away and can act as a guidepost to locating the area to star hop to it. Both planets remain in the evening sky for the rest of the year and into early 2027 with Neptune fading into the evening twilight by February and Uranus by April.
Given a night of steady seeing, a small telescope should be capable of resolving the discs and revealing the colors of these remote worlds; however, both planets are too far away to observe cloud detail or moons unless the telescope has an aperture of at least 16 inches. Uranus is 3.8 arcseconds across and Neptune is 2.4 arcseconds across. They are not identical twins with Uranus appearing distinctly turquoise while Neptune is a dimmer grayish-blue.
The Barton-Brown Observatory (BBO) at the Waterville Public Library houses a research grade, 16-inch Schmidt-Cassegrain telescope and its superior optics in the relatively dark skies south of Utica’s bright city lights consistently reveal Uranus as a true turquoise globe and, during nights of perfect seeing, two of the five largest moons, Oberon and Titania, are visible. The other three moons of Uranus, Umbriel, Ariel, and Miranda, are dimmer and have yet to be seen; all five moons shine at magnitude +14 to +15. Neptune is a chilly-bluish, tiny globe with Triton shining nearby most of the time, but quite dim at magnitude +13.5.
Using a telescope of at least 16” such as the one at the BBO may increase the chances of seeing the bright north polar cloud cap of Uranus as it is pointed almost directly towards Earth, or seeing bright or dark spots on Neptune. Extremely high power will be mandatory as they will not be obvious and photography might be the best option to see them. A fun project to do is to try and capture the changing positions of Triton around Neptune and some of the moons around Uranus by photographing them on every clear night possible. Uranus and its moons will be interesting to plot as it will resemble a bulls-eye with Uranus at the center and appearing nearly pole-on to Earth. Why wait for some mission in the far distant future to explore them and send back images? Get out on a clear, crisp autumn night and explore these pastel bluish tinted worlds and make your own memories.