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The Sky This Week, 2018 March 6 - 13

Venus & Mercury in the evening twilight, and Daylight Time starts...again!
Mercury & Venus over the 26-inch telescope dome
Venus and Mercury over the dome of the USNO 26-inch "Great Equatorial" refractor,
imaged from Washington, DC on 2018 March 5, 23:40 UT
HDR composite image made from 3 exposures with a Canon EOS Rebel T2i DSLR.

The Moon wanes in the morning sky this week, diving southward along the ecliptic as she greets the rising summer constellations.  Last Quarter occurs on the 9th at 6:20 am Eastern Standard Time.  She passes the three bright planets Jupiter, Mars, and Saturn in the pre-dawn skies.  You’ll find her perched just north of Jupiter on the morning of the 7th.  Look for Luna to the northeast of ruddy Mars before dawn on the 10th.  On the following morning she will be northeast of yellow-hued Saturn. 

You have probably noticed the rapidly-lengthening days recently.  At this time of the year the Sun is making his most rapid northward progress along the ecliptic.  Each passing day now averages about three minutes longer than its predecessor.  We get a big boost in sunset times this week.  Thanks to the Energy Policy Act of 2005, we set our clocks forward by one hour at 2:00 am local time on the morning of the 11th, putting us on Daylight Time until November 4th.  Love it or hate it, this annual ritual has been around in one form or another since World War I, although the original concept of it dates to the second half of the 19th Century.  Its first application was in Germany in 1916 as a means of allowing factory workers to take advantage of natural light and save on coal-fired electric lights.  England and the allies soon followed, as did America in 1918, when Congress passed the Standard Time Act.  An interesting lobbying group helped to push the concept of Daylight Time in those days.  Food was scarce in major urban areas due to rationing, so people resorted to planting “Victory gardens”.  Daylight Time allowed workers to tend their plots after their factory shifts were finished.  A poster celebrating the passage of the act shows a happy Uncle Sam exhorting people to “Get Your Hoe Ready!”  Unfortunately, the change was not widely accepted, and the federal Daylight Time mandate was repealed in 1919.  It became a matter of local enforcement except for the years 1942 through 1945, and Daylight Time wasn’t specified in U.S. Code until 1966.  Unless you live in Arizona or Hawai’i, you’re obliged to observe it until the first Sunday in November.

The end of evening twilight finds the sky’s brightest star, Sirius, crossing the meridian.  Most of the rest of the bright winter constellations are now in the western part of the sky, leaving you only a few hours to enjoy Orion and his colorful companions.  The bright stars of the Great Winter Circle are giving way to the more subdued constellations of the spring.  By 10:00 pm Orion is sinking in the west, while the bright star Regulus leads the constellation Leo climbing in the east.  High in the northeast you should be able to pick out the seven second-magnitude stars of the “Big Dipper” asterism, part of the much larger constellation of Ursa Major, the Great Bear.  If you follow the arc of the three stars that make up the Dipper’s “handle” you’ll find the brightest star in the northern hemisphere of the sky, the topaz-hued Arcturus.  

Venus and Mercury are putting on a fine show in the west as evening twilight begins to fade.  You should be able to pick Venus out of the bright sky about half an hour after sunset.  She starts the week about five degrees above the horizon at this time.  Once you find her, look above and to the right of the dazzling planet for Mercury.  The two objects will climb a bit higher on each successive evening, and should be easy to spot with the naked eye about 40 minutes after sundown.  This will be Mercury’s best evening showing for the year, so take advantage of his proximity to Venus to track him down.

The other three naked-eye planets are still best seen in the morning sky.  Get up an hour before sunrise to see Jupiter, the brightest planet in the sky after Venus.  Jupiter reaches his first stationary point in the 9th and will gradually begin retrograde motion westward against the stars over the next few weeks.  Mars follows Jupiter and van be found between the bright star Antares and the planet Saturn.  The red planet is closing the gap with Saturn, and will pass the ringed planet toward the end of the month.

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