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The Sky This Week, 2019 April 9 - 16

Celebrate Yuri's Night!
The Moon, imaged at the U.S. Naval Observatory on 2016 November 7.
The Moon, imaged at the U.S. Naval Observatory on 2016 November 7
with the 30.5-cm (12-inch) f/15 Clark/Saegmüller refractor
and a Canon EOS Rebel T2i DSLR.

The Moon begins the week among the departing bright stars of the winter sky.  By the week’s end she heads south along the ecliptic and joins the more subdued stars of spring.  First Quarter occurs on the 12th at 3:06 pm Eastern Daylight Time.  Luna forms an attractive tringle with Mars and the bright star Aldebaran on the evening of the 9th.  On the evening of the 13th use binoculars to locate the Praesepe star cluster just over two degrees to the right of the Moon’s gibbous disc.  

April 12th is “Yuri’s Night”, an international celebration of astronomy and related space sciences.  It marks the 58th anniversary of the flight of cosmonaut Yuri Gagarin as well as the 38th anniversary of the first flight of the Space Shuttle “Columbia”.  This is a truly international observance with events taking place around the globe.  Here in Washington you can attend a special evening event at the Smithsonian’s National Air & Space Museum.  In addition to stargazing at the Museum’s public observatory, there will be special programs to commemorate the 50th anniversary of Apollo 11 mission to the Moon as well as the 50th anniversary of the release of David Bowie’s “Space Oddity” album.  Weather permitting you can also gaze at the Moon at the Analemma Society’s observatory at Turner Farm Park in Great Falls, Virginia. 

The Moon will be the most prominent object in the sky this week, and with the big anniversary of the first humans to visit its surface coming up in July it’s a great week to look at the stark landscapes of our closest celestial neighbor.  You don’t need a big telescope to enjoy the view; a steadily-held pair of binoculars will give you a better view than the one that Galileo had some 410 years ago.  A good small telescope will show an astonishing variety of detail.  From the relatively smooth plains of the so-called lunar “seas” to the rugged, battered “highlands”, the Moon’s surface offers a constantly changing play of light and shadow over craters, mountain peaks, rilles, and valleys.  While the features themselves are essentially frozen in time, their appearance constantly varies depending on local lighting conditions.  A good lunar atlas will provide a good companion to your telescopic sightings.  Learning to recognize the named features on the Moon enhances your views.  Many of the features have names that date back to the earliest era of serious selenography, and they bear testimony to the astronomers and explorers who were prominent figures in Renaissance world.  You will quickly see that virtually every feature, large or small, has a unique characteristic, and the variety is truly staggering.  It is often said the Moon is “looked over, then overlooked” by new telescope owners, but I have been diligently looking over Luna since the days of the Apollo missions and still haven’t seen it all.

The Moon’s waxing phase washes out many of the stars of the springtime sky.  While winter’s bright constellations retreat to the west, there are only a handful of bright luminaries to challenge Luna’s brightness.  One of these is Regulus, the brightest star in the constellation of Leo, the Lion.  You’ll find the star southeast of the Moon on the evening of the 14th.  My favorite sign of spring is a star that you’ll now find climbing in the east.  Arcturus sports a rosy tint and occupies a sparse area of the sky.  It is the brightest star in the northern hemisphere of the sky and is the fourth-brightest star in all the heavens.  At a distance of 37 light-years, it is the closest example of an evolved “red giant” star to the solar system.

Mars spends the week drifting eastward among the stars of Taurus.  He spends the week not far from The Bull’s brightest star Aldebaran.  Both objects have a distinctive ruddy hue. 

Giant Jupiter may be found on the meridian at around 5:30 am local time.  The giant planet reaches the first stationary point in this year’s apparition, pausing his eastward motion along the ecliptic before gradually beginning to backtrack toward the stars of Scorpius.  

Saturn may be found in the southeastern sky as morning twilight begins to brighten the sky.  Look for him just to the east of the “teapot” asterism of Sagittarius.  He is slowing down as he approaches his first stationary point, which will occur at the end of the month.

Venus is becoming more difficult to spot in the gathering morning twilight.  You’ll need a clear view of the southeast horizon to catch her.  She is only five degrees above the horizon half an hour before sunrise.

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