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The Sky This Week, 2019 February 26 - March 6

Springtime stars on the rise.
The Big Dipper rising, imaged 2019 February 16 from Mollusk, Virginia
The Big Dipper rising, imaged 2019 February 16 from Mollusk, Virginia
with a Canon EOS Rebel SL2 DSLR.

The Moon holds court in the pre-dawn sky this week, passing the planets Jupiter, Saturn, and Venus as she wanes to a thin crescent.  New Moon occurs on March 6th at 11:04 Eastern Standard Time.  Luna may be found just over two degrees northwest of Jupiter on the morning of the 27th.  Look for Saturn to the east of the Moon on the morning of March 1st.  On the following morning look for Luna’s crescent near the bright glimmer of Venus in the brightening twilight of dawn.

With the Moon absent from the evening sky we are ramping up for the next monthly observing campaign for the Globe at Night citizen-science program.  Once again the focus falls on the constellation of Orion, the Hunter, winter’s most prominent star pattern.  Orion crosses the meridian at 7:30 pm, placing him in ideal position to estimate the brightness of the faintest stars you can see within his bounds.  Whether you use the web-based reporting form or the smart-phone apps, here is a great opportunity to contribute to a world-wide database documenting the brightness of our night skies.  In particular, if you live in an urban area, your contribution is important and easy to make since Orion is populated with many bright stars.

As the evening hours pass you’ll find Orion and his bright winter cohorts move into the western sky.  At the same time the first stars of the springtime sky are rising in the east.  Two constellations that I consider to be true harbingers of the coming season are well-placed by 10:00 pm.  Leo, the Lion follows the stars of the Great Winter Circle and may be found high in the east.  Leo is led by the first-magnitude star Regulus, which lies at the bottom of a semicircular asterism known as “The Sickle”.  Leo’s second-brightest star is a part of this asterism and is called Algieba.  This star is one of my favorite stars to observe in the small telescope.  Your first view of Algieba will show a golden-yellow luminary that under careful scrutiny reveals to be a close double star.  The two components are separated by just over four seconds of arc and are of similar brightness and color.  The pair form a true physical binary with an orbital period of just over 500 years.  Regulus and The Sickle depict the head of Leo; his hindquarters are demarked by a right triangle of stars to the east of his head.  The brightest star in this group is called Denebola, which appropriately translates into “the tail of the lion”.

High in the northeast above Leo is another group of stars that’s widely known to northern hemisphere skywatchers.  Although it doesn’t possess any first-magnitude stars, it is a very prominent grouping of seven second-magnitude stars popularly known as the Big Dipper.  The Dipper is a part of the much larger constellation of Ursa Major, the Great Bear, but most of the rest of the stars in this constellation require a dark site to see well.  The seven stars of the Dipper are also known as The Plough in England and Ireland and Charles’ Wain or wagon in much of Germanic Europe.  The two stars that form the end of the “bowl” of the Dipper, Dubhe and Merak, are also known as The Pointers since they show the way to Polaris, the North Star.  Mizar, the star that forms the bend in the Dipper’s “handle”, is another interesting telescope target.  Keen-eyed observers may notice a fainter star nestled close to Mizar, but point the telescope at these stars and you’ll see that Mizar is itself a double star!

Look for Mercury in the west as evening twilight begins to darken the sky shortly after sunset.  The fleet planet reaches greatest elongation east of the Sun on the 27th, then falls rapidly toward Old Sol, disappearing in twilight glow by the end of the week. 

Mars is about halfway through his trek through the stars of the constellation of Aires, the Ram.  This small constellation consists of three stars located about ten degrees north of the red planet.  Mars’ tiny disc now shines some 30 times fainter than he did at last year’s favorable opposition, but he is still the brightest object in this part of the sky.  His ruddy hue should also help identify him.

Jupiter gets a visit from the Moon before dawn on the 27th.  The giant planet will rise at around 2:00 am by the end of the week, and he should be well-placed for telescopic examination as morning twilight begins.

Saturn follows Jupiter across the southern sky.  He rises about two hours after Jupiter, so you’ll have to battle twilight glow to get a good look at him.

Venus rises about 45 minutes after Saturn, but unlike her more far-flung compatriot she should be easily visible in the gathering twilight.  Look low in the southeast for her bright glow about 45 minutes before sunrise.

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