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Country Blues

by Perry Pezzolanella

Two distant planets are often ignored if not forgotten among the other planets but should be given consideration as they are quite easy to see once they are found. Uranus and Neptune are often thought to be too dim and small to seriously observe, but both are actually quite easy with a little determination. Under clear, moonless skies in the dark countryside, it is possible to find Uranus and Neptune with the help of the finder charts that accompany this article.

Uranus (magnitude +5.7) 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 (2%) in Uranus' atmosphere absorbs the red component of sunlight and scatters the blue creating a turquoise hue. Neptune appears even bluer since it is not as hazy as Uranus and has slightly more methane (3%). These colors are dramatic whenever they are near stars of contrasting colors.

Uranus spends 2014 in Pisces to the left of the Great Square of Pegasus while Neptune is in Aquarius below the Water Jar asterism. Neptune will be at opposition on August 29 while Uranus will be at opposition on October 7. Rising at sunset and setting at sunrise, both worlds will be up all night on these dates. They will remain in the evening sky for the rest of the year and into early 2015 with Neptune fading into the evening twilight by February and Uranus by March.

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 3.7 arcseconds across and Neptune is 2.4 arcseconds across. The planets appear distinctly different with Uranus having a rich turquoise hue while Neptune is a chilly, icy-blue disc.

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 city lights has revealed Uranus as a true turquoise globe with two moons, Oberon and Titania, readily visible. The other three rather large moons of Uranus: Umbriel, Ariel, and Miranda, are more difficult to see, and all five moons shine at magnitude +14 to +15. Neptune appears like a tiny bluish globe with magnitude +13.5 Triton shining dimly nearby, but quite easy to identify.

Observing detail on each planet is now in the realm of the astrophotographer thanks to the increasingly advanced technology in photography, which is now rivaling and even exceeding the quality of large telescopes decades ago. Astrophotographers have been able to photograph the white spots and dusky banding that has been active on both Uranus and Neptune. A magnification of at least 500x for Uranus and 900x for Neptune along with a yellow-green (Wratten #11) filter are required in order to have a chance at photographing any detail.

The BBO is in dark skies well south and away from the bright lights of Utica and on the southern edge of Waterville, perfect for finding and observing faint objects. This will assure that Uranus and Neptune will be less of a challenge to find and allow for more time to enjoy their soft bluish glow in the dark country night.