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The Sky This Week, 2018 April 17 - 24

Celebrate Dark-sky Week and Astronomy Day!
Crescent Moon, 2018 February 20, imaged with the USNO 12-inch telescope
Crescent Moon, 2018 February 20 @ 23:30 UT,
imaged with the USNO 30.5-cm (12-inch) f/15 Clark Saegmüller refractor
and a Canon EOS Rebel T2i DSLR, composite of nine exposures.

The Moon returns to the evening sky this week, waxing through her crescent phases as she wends her way through the setting winter constellations.  First Quarter occurs on the 22nd at 5:46 pm Eastern Daylight Time.  Luna begins the week in the company of bright Venus in the fading evening twilight on the 17th.  On the following evening she may be found just west of the bright star Aldebaran in Taurus.  If you look at her with binoculars you’ll find her embedded in the V-shaped Hyades star cluster.  Another binocular target is flanked by the Moon on the evening of the 21st.  Take your binoculars and look just to the left of the Moon for the “Beehive” star cluster.  To round out the week, Luna will cozy up to the bright star Regulus in the constellation of Leo, the Lion.

Global Astronomy Month continues with the observance of International Dark Sky Week, which runs through the evening of the 21st.  Created by then high-school student Jennifer Barlow in 2003, this week-long observance has become a centerpiece of Global Astronomy Month and culminates on Astronomy Day, April 21st.  The idea is to simply make people aware that there is more to the night sky than street lights and neon signs and to call attention to the overuse of artificial nighttime lighting.  Not only does artificial night lighting obscure our view of the stars, it interferes with the natural biology of hundreds of species, humans included.  Migratory birds are disoriented in their annual flights, marine creatures have their reproductive cycles disrupted, and our own circadian rhythms are disrupted, particularly in the production of melatonin, which is vital for the body’s ability to “recharge” itself during a good night’s sleep.  Citizen awareness of the issues may lead to the more efficient use of nighttime lighting and not only provide an economic benefit due to lower energy consumption but also bring back a better view of the night for everyone.

As we mentioned above, the 21st is Astronomy Day, a global celebration of the night sky.  Local astronomy clubs, planetariums, and public observatories will be hosting events throughout the world.  Here in the Washington, DC area, the Northern Virginia Astronomy Club will host its annual Astronomy Day Star Party at C.M. Crockett Park in Midland, Virginia from 3:00 until 11:00 pm.  This is a great opportunity to see astronomy-related demonstrations, safely observe the Sun, and see celestial sights through a variety of telescopes provided by club members.  While the park charges a nominal entry fee, all of the program activities are free.  For other events in the area, see our web page with links to other astronomy-related resources in the local area.

The evening twilight sky is where you’ll find the bright glow of Venus, which should appear shortly after local sunset.  As the sky darkens she dominates the scene and by the end of the week sets at around 10:00 pm.  She receives a visit by the slender crescent Moon on the evening of the 17th, which should provide a fine photo opportunity.

Jupiter continues to make inroads into the evening sky.  This week the giant planet rises before 9:30, and he should be easy to spot in the southeast by 11:00 pm.  Old Jove is slowly creeping westward among the stars of the obscure constellation of Libra, the Scales, inching toward the star Zubenelgenubi, the southernmost of the constellations two brightest stars.  Jupiter will reach opposition in a few more weeks, at which time he’ll be visible all night.

Saturn is located near the top of the “Teapot” asterism in the constellation of Sagittarius.  He will stay in this general area for the next few months.  Just below Saturn you’ll find a small fuzzy patch of light in your binoculars.  A modest telescope will reveal a swarm of countless faint stars that form the globular star cluster Messier 22, one of the finest objects of its type in the heavens.

Mars is now well east of Saturn, and he’ll move another several degrees further eastward this week.  Earth is closing in on the red planet as we prepare for his opposition in July.  Mars’ disc is now growing, and this week crosses the 10 arcsecond apparent diameter threshold.  This is when owners of modest telescopes should be able to start seeing details on the planet’s distant surface.

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