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The Sky This Week, 2014 April 22 - 29

Celebrate International Dark Sky Week!
Mars_140422_0329_01small.jpg 
Mars, 2014 April 22, 03:29 UT
Imaged with USNO's 12-inch f/15 Clark/Saegmüller refractor

The Moon wanes through her crescent phases in the morning sky this week, wending her way through the rising autumnal constellations. New Moon occurs on the 29th at 2:14 am Eastern Daylight Time. You will find Luna in the company of bright Venus in the morning twilight of the 25th and 26th.

This week we celebrate International Dark Sky Week, dedicated to raising awareness of the importance and benefits of a dark nighttime environment. Begun in 2003 by a high-school student named Jennifer Barlow, it is now observed worldwide by an ever-increasing number of people and organizations. The practical benefits of better outdoor night lighting include better quality lighting for streets and business areas, less stray light reflecting up into the night sky, and tangible energy savings, both in costs and non-renewable resources. Recent studies have also shown that darker skies are beneficial to us, improving our sleep cycles and circadian rhythms, and hundreds of animal species benefit by reduced glare at both ground level and in the sky. Please visit the website of the International Dark Sky Association for more information on dark sky awareness and events occurring this week. The U.S. Naval Observatory is proud to be a lifetime sponsor of the IDA.

In conjunction with International Dark Sky Week, this week finds us in the middle of the "Globe At Night" citizen-science program April observing campaign. The absence of the Moon in the evening sky affords a great opportunity to see just how dark your favorite observing site is, and here is a way that you can report your findings for the betterment of science. April is a good month to do this since it’s fully dark by 9:30 pm and the haze and humidity of summer have yet to set in. Your objective is to locate the constellation of Leo, the Lion, which straddles the meridian high in the south at 10:00 pm. Count the number of stars you see in the constellation, then compare your observations to the charts on the Globe At Night website. It only takes a few minutes to do before turning in for the night, and each observation helps to chart the brightness of the night sky around the world.

Jupiter is still well-placed for observing in the western sky after sunset. He pops into view almost immediately after the Sun goes down and offers a fine telescopic target even in bright twilight. As darkness settles the giant planet dips lower toward the west, eventually setting just after 1:00 am. His apparent disc is now only about 2/3rds the size it was back at opposition in January, but a night with steady air should still reveal the planet’s dark equatorial cloud belts and four bright Galilean moons.

Mars As evening twilight ends ruddy Mars is well up in the southeastern sky. The red planet glows like a distant coal in the stars of Virgo, and contrasts nicely with the blue tint of the bright star Spica 11 degrees to the southeast. You’ll also probably notice that Mars is steadily closing in in on the second-magnitude star Porrima. By the end of the week the two objects will be about a degree and a half apart. Through the telescope Mars is putting his best face forward for North American observers; his most prominent dark albedo feature, the "Syrtis Major", will face our Earthbound telescopes throughout the week.

Saturn follows Mars into the sky in the later stages of the evening. By midnight he’s well up in the southeast as he slowly wends his way westward among the stars of the obscure constellation of Libra, the Scales. Saturn doesn’t have the brazen red glimmer of Mars; he shines with a much more subdued yellow hue. However, once you’ve spent some time trying to glean detail from Mars’ diminutive disc, reward yourself with a view of the solar system’s most unusual world. Saturn will reach opposition in a few more weeks.

I was quite surprised to see Venus through my window this morning, ducking in and out of the clouds. My view is nearly due east, and for most of the current morning apparition the dazzling planet has been obscured by trees and houses from my sight. The planet is hugging the eastern horizon, but each passing day brings her a bit farther northward. She should be there to greet me for the next several months.

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