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The Sky This Week, 2015 March 31 - April 7

A special month for stargazing.
Jupiter, 2015 March 25, 01:12.5 UT

The Moon brightens the evening sky this week, with her bright disc coursing through spring’s signature constellations.  Full Moon occurs on April 4th at 8:06 am Eastern Daylight Time.  This particular Full Moon undergoes the year’s first total lunar eclipse which will be partially visible from the western U.S. and best seen from the mid-Pacific Ocean.  Here in Washington we’ll see the penumbral phase and the first 40 minutes of the umbral phase before the Moon sets; at this time about one-third of Luna’s disc will be in the Earth’s umbral shadow.  April’s Full Moon is popularly known as the Grass Moon, Egg Moon, and Pink Moon.  This year we can also call it the Paschal Moon, as it is the first Full Moon following the vernal equinox.  This is the most important Full Moon of the year for Christians and Jews since it fixes the dates of Easter and Passover.  Look for Luna near the bright star Regulus on the evening of the 31st.  On the night of the 4th the moon glides just three degrees north of the bright star Spica.

The month of April recognizes our love of the night sky as Global Astronomy Month, a program sponsored by Astronomers Without Borders.  Throughout the month there will be a multitude of events aimed at increasing awareness of the night sky, our place in the universe, and our various cultural interactions with the night.  All month long there will be observing challenges, art and photo contests, educational opportunities, and special observing days and nights.  Highlights include the upcoming lunar eclipse, SunDay on April 12, and the Global Star Party on April 25.  You can also participate in the monthly Globe at Night observing campaign between April 9th and 18th, and celebrate International Dark Sky Week between the 13th and 18th.  Visit the various Web pages to learn more details about this action-packed month.

The bright Moon washes out most of the fainter stars in the sky, but you can still find winter’s brightest luminaries in the southwestern sky as evening twilight ends.  Orion dominates this part of the sky, and the Hunter’s three “Belt Stars” point the way toward Sirius, the brightest star in the night sky.  As Sirius follows the winter stars to their rest over the western horizon at around midnight it can undergo some very interesting phenomena associated with its light passing through the dense layer of air just above the horizon.  It’s not unusual to see Sirius flicker dramatically, pulsing through all the colors of the rainbow.  This effect is particularly apparent when sighted over water, and I fondly remember all of the “UFO” calls I’d get in my planetarium days from people who lived in western Michigan who sighted this flickering phenomenon as Sirius set over Lake Michigan. 

Venus is also located in the western sky, but she is far brighter than Sirius.  She also undergoes dramatic scintillation effects when she’s close to the horizon and is often mistaken for something “supernatural”.  Venus can also be seen while the Sun is still up, usually in the half-hour before sunset, which can also prompt calls to the local planetarium.  Even some astronomers can be fooled by Venus, though; my high-school astronomy teacher once tried to shoot Venus down while on convoy duty in World War II!

Jupiter lords over the early evening hours and is ideally placed for viewing from sunset until midnight.  He’s currently located in the obscure constellation of cancer, the Crab, whose one interesting feature is a beautiful binocular star cluster known as the Praesepe or “The Beehive”.  Jupiter is now just five degrees east of the cluster, so if you’re perusing the giant planet take a few minutes to look for it. 

Late-night skywatchers can just catch a glimpse of Saturn rising before midnight in the southeastern sky, but the best time to view him is still in the hours before dawn.  The ringed planet sits among an attractive group of second-magnitude stars that form part of the “head” of Scorpius, the Scorpion.  You’ll find the waning gibbous Moon just two degrees west of Saturn before dawn on April 8th.



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