StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

JUNE 2008

JUNE STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

Print Large Sky Charts For 10 p.m. EDT: NORTH | EAST | SOUTH | WEST | ZENITH

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[Phoenix on Mars]

The slightly lumpy texture of the north polar plains of Mars suggests episodes of melting and freezing in this Phoenix lander image taken on day one of its mission, May 25, 2008. NASA JPL-Caltech, University of Arizona image...

615 JUNE 1, 2008: Vernal Sky: With the moon new on Tuesday, this is the perfect week to venture out-of-doors to view the vernal sky. Luckily, we are still in a spring weather pattern which has produced temperate days and many clear starry, light jacket nights. Make your observations about 10 p.m. when it has become completely dark. Facing north, one of the first things that you’ll notice is the Big Dipper high in the sky, but already tipping cup down. The luminaries farthest left are the Pointer Stars. They aim downward and to the right to the North Star of the Little Dipper, and upward and to the left to bisect Leo the Lion. Currently, the Little Dipper stands handle down, cup up with Polaris as its lowest star. The smaller dipper is still a challenge, even from suburbia, but low power binoculars will reveal it quite nicely. The top stars of its cup, brighter Kochab (left) and Pherkad, are usually visible to the unaided eye. You will know that you are in Leo by the close pairing of its brightest star, Regulus, with even brighter Saturn to Regulus’ left. Look for the familiar backwards question mark which will signify Leo’s head and the front of his body. Right and downward, about six times the Saturn-Regulus distance, will shine Mars. Go back to the Big Dipper and follow the arc of its handle over the zenith to orangey Arcturus of Bootes the Headsman and further along to blue Spica of Virgo the Virgin. To Spica’s right, and down a bit, will be a quadrilateral of stars known as Corvus the Crow. Binoculars will reveal two fainter stars which help to outline Corvus’ hunched back. If you look towards an open eastern horizon, you’ll note three bright stars that form the corners of the Great Summer Triangle. Vega, the highest, Deneb, below and to the left of Vega, and horizon-hugging Altair are already standing at summer’s gate.

616 JUNE 8, 2008: Phoenix Sees Ice on Mars: In 1894, Boston millionaire, entrepreneur, author, and diplomat, Percival Lowell, founded the Lowell Observatory in Flagstaff, Arizona. Convinced that Mars harbored intelligent life, Lowell meticulously watched, until his death in 1916, the Red Planet’s changing seasonal effects and the waves of darkening which accompanied them. He believed that canals transported water from the polar regions of Mars through a series of pumping station oases to the warmer equatorial climes. Lowell’s writings and scientific reports were widely followed by the public and were directly traceable to H. G. Wells’ “War of the Worlds,” as well as the Mercury Theater’s radio broadcast of Halloween Eve, 1938. This romantic notion of Mars as the abode of life was shattered in the 1960s when Mariner (4, 6, and 7) spacecraft flew past the Red Planet and recorded a cratered landscape similar to the moon’s surface. But when Mariner 9 went into orbit around Mars in 1971, a dynamic and evolving world was unveiled with volcanoes, canyons, dust storms, and sinuous channels that could only have been made by liquid water. Subsequent NASA orbiters, landers, and rovers propelled by these earlier discoveries have shown that liquid water once flowed over the Martian surface, was contained in saltwater oceans, and may still be seeping onto the surface today as groundwater or water saturated debris flows. In less than two weeks after Phoenix, NASA’s water sniffing Martian lander touched down (May 25), it is presenting evidence for the presence of ice underneath its landing platform, where its braking rockets scoured the Martian polar surface before coming to rest. Photos are online at the URL below. Lowell must be chuckling ever so contently from his grave as he and many others scientists anticipate the discovery of life on the Red Planet.

617 JUNE 15, 2008: Bootes on High: Situated high in the northwestern spring sky during the early evening hours is Bootes the Herdsman or Bear Driver. He was put into the heavens to insure that the big and little bears did not stray, but continued to circle eternally around the North Star. Arcturus, Bootes’s brightest luminary, is a real barn burner and is now considered the third brightest star of the night, after winter’s Sirius, the Dog Star of Canis Major, and Canopus of Carina, the (ship’s) Keel, also visible in winter, but only from the southern US. Arcturus, an aging giant at a distance of 36.7 light years from the Earth, can be easily located by continuing the “arc” of the Big Dipper’s three-star handle to the first bright luminary that is encountered. The Dipper is currently located cup down, high in the northwest. Viewing Arcturus with light-grabbing binoculars will reveal its yellowish-orange hue more distinctly and unmistakably against the background of nearby, less colorful stars. Although finding Arcturus is a breeze, locating the rest of this kite-shaped constellation from an urban or suburban setting can be downright arduous. If binoculars are not handy, use averted or side vision and scan the sky with the peripheral part of your eyesight, which is more sensitive to lower light levels, and should make the fainter stars of Bootes pop into its traditional kite like figure. Facing northwest at 10 p.m., the Big Dipper will be at a high altitude and to your right with its handle up. Following the arc of the handle, Arcturus should be slightly to your left, and Bootes, with its symmetrical structure, should be lying on its side, stretching outward towards the right, with the top of the kite above the handle of the Big Dipper. An online Bootes locator map is available at the URL below by clicking on “this week’s StarWatch” button.

618 JUNE 22, 2008: M13: Best Globular North of the Equator: At this time of the year when everyone is thinking about summer, the spring sky is most easily accessible right after dark. It holds one of the finest celestial gems of the northern hemispheric skies, M13. It is a globular cluster, a galaxy “wannabe” with about a half million stars that never made it to the majors. Our Milky Way is littered with about 100 globulars, the finest being, Omega Centauri, containing about one million members, but best seen from south of the equator. One incredibly dark night at Chaco Culture National Historical Park in NW New Mexico, I did see both together in the same sky with the unaided eye. Through binoculars Omega, low in the south nearly scraping the top of Fajada Butte, appeared more robust than M13 which was high in the east. Binoculars will be needed to find M13 from suburban skies, as well as a star map like the one posted in “this week’s StarWatch” at the URL below. Facing north, use the Big Dipper, cup down, handle up, and high in the NW to begin your search. Above the Dipper is the “kite” portion of Bootes the Bear Driver discussed last week. Above the kite is Corona Borealis the Northern Crown, a half circlet of faint stars appearing like a “C” and an easy view in binoculars. Far to the Crown’s right will be the brilliant blue-white star Vega of Lyra the Harp. Bisecting a line from the “C” to Vega will put you in the middle of the Keystone of Hercules the Strongman’s body, shoulders down, waist up. Above the lower left star and about one third of the distance to the upper left star of the Keystone will be M13, a fuzzy but unmistakably distinct glow, representing its one half million luminaries. Once you’ve found it, try seeing the Keystone and M13 without binoculars, a true challenge if you live in suburbia or even in a more rural locale.

619 JUNE 29, 2008: Planets, Moon Make Summer Sky Sparkle: In the western sky about one hour after sundown, you can watch Mars catching up to Saturn as they approach conjunction with each other on July 10. Both planets are gaining distance from the Earth due to our orbital motion and will be brought eventually into conjunction with the sun; Saturn on September 4; then Mars on December 5. So these planets are not at their brightest, and binoculars will be helpful in making their initial identifications easier. On Sunday Mars will be about 5-1/2 degrees from Saturn, about the same distance that the Pointer Stars of the Big Dipper are from each other. More interestingly will be Mars’s distance, just over one degree, from the bright star Regulus in the constellation of Leo the Lion. On Monday and Tuesday, that distance shrinks to only three-quarters of a degree, a splendid sight for all three objects, if the sky is free of summer haze. On Friday, Independence Day, an ultra thin horned moon enters into the scene, but it is still over 20 degrees from Mars, now between Regulus (right) and Saturn. By Saturday that distance has decreased to about nine degrees. Sunday, July 6, however, is the best grouping, a thin waxing crescent moon lying in a loose association with Saturn, Mars, and Regulus. The waxing moon heads out into the vernal sky overtaking blue-white Spica of Virgo the Virgin by July 10, and then into the summer sky, passing red supergiant Antares of Scorpius the Scorpion by the 14. After Scorpius it is obvious that the moon is headed for another really bright luminary low in the southeast, but this one is shining with a steadier light. You’ll be viewing Jupiter. Through binoculars several faint stars may be seen very near Jupiter, its four, large Galilean satellites. The nearly full moon approaches and passes Jupiter by July 17.

[June Star Map]

[June Moon Phase Calendar]