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The Sky This Week, 2016 March 8 - 15

Springing forward in time.
M42_AR102_160307_03small.jpg
Messier 42, the Great Nebula in Orion, imaged on 2016 March 7
under urban skies with a 10.2-cm (4-inch) f/6.5 refractor
and a Canon EOS Rebel T2i DSLR camera

The Moon returns to the evening sky this week, waxing to First Quarter on the 15th at 1:03 pm Eastern Daylight Time. She joins the stars of the Great Winter Circle by the week’s end. Look for Luna south of the Pleiades star cluster on the evening of the 13th. She may be found just east of the bright star Aldebaran on the following evening.

Yes, I slipped the word "daylight" into the time of the First Quarter Moon. This is the weekend when we set our clocks one hour ahead as we "spring forward" for Daylight Time. This annual ritual affects everyone in the country except for residents of Arizona and Hawai’i. In Hawai’i’s case it’s because the state is located in the tropics where the annual excursion of day/night change is relatively small. Arizona is excepted because the residents there never adopted Daylight Time when it was regulated by state statutes. The Federal law governing time zones and Daylight Time rule wasn’t codified until 1966; Arizona and certain western counties in Indiana were excepted. Since then the law has been modified twice, with the most recent bill passing Congress in 2005. Under this act all of Indiana now observes Daylight Time, but Arizona still stays on Mountain Standard Time. Whether you like Daylight Time or not, the U.S. Naval Observatory has nothing to do with it. Regulations regarding enforcement of standard time laws falls under the purview of the Department of Transportation. We provide the time-scale on which civil time is based, but we don’t tell you what to do with it! So, as a friendly reminder, Daylight Time officially begins at 2:00 am on Sunday morning, March 13th. Be sure to set your clocks ahead one hour and maintain that offset until November 6th, when we "fall back".

The early evening hours are still dominated by the bright stars of the Great Winter Circle, but at this time of the year those stars seem to speed toward the western horizon at a fast pace. This is due to the fact that all stars transit the meridian four minutes earlier every night and that at this time of the year the length of daylight is increasing at its fastest rate. Later sunsets mean later twilight times, which cut into the time that the winter stars are visible in relative darkness. You still have time to enjoy the sights of Orion and his environs, but if you wait much longer you’ll find them wallowing in the west.

Jupiter now rises just before sunset, and by the time evening twilight deepens the sky to a dark blue you’ll find him shining brightly in the east. The giant planet is now in the prime-time of his current opposition, a tempting target for telescopes of all sizes. For the urban stargazer this is a great week for casual observing, with the Moon and Jupiter offering contrasting views. The barren cratered surface of Luna is the antithesis of the cloud-shrouded atmosphere of Jupiter. You’ll also notice that the entire apparent disc of Old Jove is about the same size as a modest lunar crater. However, the vast difference in distance between the two explains why an object the size of our Moon would appear as a tiny spot at the distance of Jupiter. What amazes me is that we can see features this small across the gulf of over 400 million miles in modest earthbound telescopes.

Mars rises at around midnight as the week opens, then gets thrown back by an hour as we shift to Daylight Time. The best time to see him is still before sunrise, and starting on the 13th you won’t have to get up super-early to see him. He is becoming brighter with each passing week as he marches eastward against the stars. This week he closes in on the second-magnitude star Graffias, northernmost star in the "head" of Scorpius. You’ll find the two objects very close together on the morning of the 16th.

You’ll find Saturn some 13 degrees east of Mars this week, shining at about the same brightness but with a yellowish hue. They are close to the meridian about an hour before sunrise and form an attractive triangle with the bright star Antares, the brightest luminary in Scorpius.

USNO Master Clock Time
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