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Thu04242014

Last updateSat, 11 Jan 2014 11am

Astronomy

April 2014 at dusk: Jupiter is clearly the brightest “star” in evening twilight during April. Mars briefly equals or slightly outshines Sirius as the red planet passes opposition and makes its closest approach to Earth in the second week. Next in apparent brightness are Arcturus and Capella, high in the sky and easily seen. Slightly fainter Saturn rises in the east-southeast around mid-twilight at month’s end.

In the eastern half of the sky, Regulus, Arcturus and (barely) Mars are already up and ascending on April 1. As Earth passes between Mars and the sun on April 8, Mars is at opposition to the sun and visible all night. The same alignment occurs with the star Spica just five days later.

The moon forms striking gatherings with stars and planets during the first half of April. The waxing crescent will be a beautiful sight during the first few evenings in April as it climbs higher each night.

On Thursday evening, April 3, the moon will appear close to the lower right of Aldebaran, eye of Taurus, and among the stars along the right side of the “V” of the Hyades star cluster forming the Bull’s face. At 8:17 p.m., as seen from the Coachella Valley, the leading dark edge of the moon will occult, or cover up, the fourth-magnitude star Delta-3 Tauri, causing the star to suddenly blink out. The occultation will be best seen with binoculars or a telescope. Just more than an hour later, about 9:25 p.m., the star will reappear at the bright edge of the moon; it will not be as easy to observe the exact moment of its reappearance.

On Sunday evening, April 6, the moon, nearing first-quarter phase, passes 5 degrees south of Jupiter.On the next evening, the moon will be widely south of Pollux, one of the Gemini Twins, and on Thursday, April 10, it will pass widely south of Regulus, heart of Leo, the Lion.

During all of those evenings, the waxing moon will be tracking southof the ecliptic, or “below” Earth’s orbital plane—but that will come to an end late on the night of Monday, April 14, as the full moon returns close enough to our orbit plane to be completely immersed in the umbra, or dark central core of Earth’s shadow—causing a total lunar eclipse! (See below for information on a public viewing event.) The eclipse begins as the moon begins to enter the Earth’s umbra at 10:58 p.m.

The Earth’s diameter is nearly 3.7 times that of the moon, but the Earth’s shadow during this eclipse will appear only 2.7 times as large as the lunar disk. That’s large enough for the moon to easily fit, with plenty of room to spare!

As more of the moon is immersed in Earth’s shadow, the reddish color of the shadow will become noticeable. The reddish illumination is sunlight which has passed through the Earth’s atmosphere and gotten refracted into the Earth’s shadow. The total eclipse begins at 12:07 a.m., early on Tuesday morning, April 15.

The 78 minutes of total eclipse is a perfect time to use binoculars to locate the asteroids Vesta (magnitude 5.7) and Ceres (7.0), at peak brightness and just 2.4 degrees apart in Virgo, an easy star-hop from the dimmed moon and Spica. These asteroids are the destinations of the Dawn space mission; Dawn has already visited Vesta and is on its way to Ceres, arriving there in 2015.

Deepest eclipse occurs at 12:46 a.m., when the northern edge of the moon comes closest to the center of Earth’s shadow. Total eclipse ends at 1:25 a.m., and the moon’s withdrawal from the umbra will be complete at 2:33 a.m.

April 2014 at dawn: Venus continues to dominate the morning sky. Find it in the east-southeast in morning mid-twilight, drifting farther north as the month progresses. A telescope shows Venus in gibbous phase, fattening from 54 to 66 percent full, but shrinking in apparent size as it recedes from Earth. Saturn is a steady yellow “star” sinking slowly in the southwest. To Saturn’s lower right are bright reddish Mars and blue-white first-magnitude Spica, but they drop below the west to west-southwest horizon before month’s end, after passing opposition on April 8 and 13, respectively.

Other bright objects in the morning sky are golden Arcturus, well up in the west to upper right of Mars and Spica; reddish Antares, heart of Scorpius, in the south-southwest to southwest; and the Summer Triangle of Vega, Altair and Deneb high in the east, topped by its brightest member, Vega.

April’s waning moon, just hours after the lunar eclipse, is still close to Spica and Mars at dawn on the 15th. Early on the morning of the 17th, the moon passes closely south of Saturn, and on the 18th, the gibbous moon passes widely north of Antares. The last-quarter moon on the morning of April 22 will be 5 degrees northof the ecliptic, near stars marking the head of Capricornus, the Sea-goat. On the mornings of April 25 and 26, the crescent moon will appear near Venus. The new moon will occur on April 29.

Astronomical Society of the Desert Viewing

The Astronomical Society of the Desert will host a public viewing session for the total lunar eclipse on Monday night, April 14, starting at 10:30 p.m., at the Coachella Valley Preserve, 29200 Thousand Palms Canyon Road. Members will bring their telescopes to provide enhanced views of the eclipsed moon, as well as the three bright outer planets—Mars, Jupiter and Saturn.

Folks coming to the viewing session are encouraged to bring binoculars to enjoy the eclipse and the deep sky objects which will become visible as the sky darkens while the moon is increasingly covered by Earth's shadow.

During the total phase of the lunar eclipse, places far enough away from brightly lit cities will enjoy very dark skies. Vesta and Ceres, the two asteroids being visited by the Dawn Space Mission, will be easily seen in binoculars during the total eclipse.

For more information and directions, go to www.astrorx.org or call 760-771-4607. Bring the kids; it’s a great educational experience for them!

Robert C. Victor was a staff astronomer at the Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs.