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The Sky This Week, 2016 March 1 - 8

The night's bright lights, some good, some bad.
Jupiter & three moons (plus a shadow), 2016 March 1, 03:44 UT

The Moon skims the southern horizon in the pre-dawn sky this week, passing through the rising constellations of summer and early autumn. New Moon occurs on March 8th at 8:54 pm Eastern Standard Time. Look for Luna to the northeast of Saturn before sunrise on the 2nd. If you have a flat southeastern horizon and a clear sky try to find the slender waning crescent Moon just three degrees to the north of dazzling Venus.

The March campaign for the Globe at Night citizen-science project gets underway on the 1st and runs through the 10th. This project is designed to involve interested people in the measurement and documentation of sky brightness from all over the world. The data collected by volunteer observers will be analyzed to determine the spread of light pollution, which is becoming an environmental issue that not only affects our view of the night sky but also some of the most basic rhythms in Nature. We now know that bright lights illuminating the sky affect migratory birds and sea turtles, and a growing body of evidence is finding links to a number of human conditions as well. Brightening skies also tell us something about our rampant consumption of energy resources. Your participation in this study is quite simple; just go out and see how many stars you can see in the constellation of Orion. You can submit your results via the project’s web page, or download star-measuring apps for your smart phone that will take your measurements and submit them "on the fly". From dark locations well away from the city you should be able to see more than 30 stars within The Hunter’s bounds; urban observers may see no more than eight. Whatever result you get, it’s an important data point. You’re encouraged to submit many observations from different locations throughout the year. This is a great time to start, since Orion is one of the easiest constellations to identify.

A sure sign of impending spring is seeing Orion just west of the meridian at the end of evening twilight. You’ll find the rest of the bright stars of the Great Winter Circle well placed at 8:00 pm, with the gold-hued Capella dominating the view near the zenith and the blue-white glow of Sirius to the south. Sirius is the brightest star in the sky due to its relative proximity to the solar system and its intrinsic brightness. It shines with a luminosity some 25 times that of the Sun and lies just 8.6 light years away from us. To the ancient Egyptians the star represented Thoth, the god of wisdom and writing, and its first appearance just before sunrise anchored the Egyptian calendar. From our latitude Sirius never gets higher than about 35 degrees above the horizon, so its apparent "twinkling" is a good indicator of the stability of the atmosphere. If its light is steady it is a good night to drag the telescope out to view fine details on the Moon and planets; if it jumps around and flickers through the colors of the spectrum leave the telescope inside and enjoy the view with the naked eye or through binoculars.

Giant Jupiter reaches opposition on the morning of the 8th. For the nights immediately surrounding the date Old Jove will rise at sunset and set at sunrise. You’ll see him in the east at the end of evening twilight, and he’ll cross the meridian close to local midnight. At this time we’ll be at our closest to the giant planet at a distance of 664 million kilometers (412 million miles). When you look at Jupiter you’re actually seeing it as it was more than 36 minutes ago due to the finite speed of light! This is the best time to view Jupiter through the telescope with his disc presenting its largest apparent size toward us. On the night of the 7th you can watch the moons Io and Europa cross the planet’s disc accompanied by their shadows; after they emerge from the disc the Great Red Spot rotates into view.

Mars continues to slide eastward along the ecliptic, closing the gap with the star Graffias in the "head" of Scorpius. You’ll find the red planet near the meridian as morning twilight begins to brighten the sky. Mars is now a full magnitude brighter than his nearby stellar rival Antares. Through the telescope his disc is now twice the size it was back in January, but it is still quite small compared to Jupiter. Nonetheless, if you have a modest telescope and steady air you should be able to glimpse his north polar ice cap and the dark wedge of his most prominent surface feature, the Syrtis Major.

Saturn follows close on Mars’ heels. The ringed planet is just east of the meridian at the onset of morning twilight. By the week’s end he’ll form an attractive triangle with ruddy companions Antares and Mars. His rings are tipped very favorably to our line of sight and can be enjoyed with almost any telescope.

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