IF IT’S CLEAR
By Fulton Wright Jr.
Prescott, AZ

Celestial events (from Sky & Telescope magazine, Astronomy magazine, and anywhere else I can find information) customized for Prescott, Arizona.

All times are Mountain Standard Time.

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March 2017

On Wednesday, March 1, starting about 7:30 PM, you can see a lot of solar system objects. First find Venus, bright at magnitude -4.6, about 18 degrees above the horizon in the west. Use a telescope to see the slim but big crescent with its horns pointing up. Next, look for comet 2P/Encke, much dimmer at magnitude 5, and halfway to the horizon below Venus. This will be the tough one to observe. Next, look up and to the left from Venus for the thin crescent Moon (magnitude -6.6). Next move a short distance to the right for Mars (magnitude +1.3, size 4.6 arc-seconds, don’t expect to see much through a telescope). Finally, look a short distance below Mars (half the distance from the Moon, but down) for Uranus (magnitude 5.9, size 3.4 arc-seconds). That gets you the Moon, three planets, and a comet.

From Thursday, March 2 through Monday, March 6 the Northern part of the Moon is tipped toward us so it is a good time to look along the terminator above and below Mare Frigoris.

On Saturday, March 4, the Moon is at first quarter phase and sets at 1:15 AM (Sunday). At 8:19 PM (Saturday), the dark limb of the Moon occults Aldebaran. At 9:34 PM the star reappears from behind the bright limb of the Moon.

On Sunday, March 12, at 2 AM, most of the rest of the United States engages in the silly ritual of going on Daylight Savings Time (springing forward by setting their clocks to 3 AM). Arizona, with its superior knowledge of the universe, remains on Mountain Standard Time.

On Monday, March 13, the full Moon rises at 7:54 PM, spoiling any chance of hunting for faint fuzzies for the night.

On Friday, March 17, Io and its shadow transit Jupiter between 10:16 PM and 12:55 AM (Saturday). Notice how the satellite and its shadow grow closer as Jupiter approaches opposition (April 7).

On Sunday, March 19, the Moon is at third quarter phase and rises at 1:17 AM (Monday).

On Monday, March 20, spring comes to the northern hemisphere and we have equal days and nights.

On Wednesday, March 22, Europa and its shadow transit Jupiter from 10:23 PM to 1:32 AM (Thursday).

On Monday, March 27, it is new Moon and you have all night to hunt for faint fuzzies.

On Friday, March 31, at around 7:30 PM, Mercury will be about 10 degrees above the western horizon. It is not going to be more visible in the evening for the rest of the year. At 8:45 PM, the Moon occults the magnitude 3.6 star Gamma Tauri. The star reappears at 9:16 PM. The program I use, Sky Safari, lists it as a very close double, but doesn’t give the secondary’s magnitude, so you might see it disappear in two steps.

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April 2017

For the comet hunters among you, check out the website: is.gd/4pcometcampaign .

On Monday, April 3, the Moon is at first quarter phase and sets at 2:05 AM (Tuesday).

On Thursday, April 6, at about 3:37 AM (ugh), Europa and its shadow move onto Jupiter. Because Jupiter is at opposition, the satellite and its shadow are near each other. At 6:02 AM they both move off Jupiter. Sunrise is 8 minutes later.

On Thursday, April 6, about 8:20 PM, Callisto is north of Jupiter. Usually the satellites are lined up east and west of the planet, so it is unusual to see one passing north of the planet. About 9:00 PM, the Moon is about 1 degree from Regulus.

On Friday, April 7, at 10:32 PM, Europa disappears in Jupiter’s shadow very close to the planet. At 1:08 AM (Saturday) Europa reappears also very close to the planet but on the other side. At 3:56 AM, Io and its shadow move onto Jupiter. They are so close that Io actually covers part of its shadow. They leave Jupiter at 6:07 AM, simultaneously with sunrise. I am sorry that I wasn’t able to arrange a more convenient time for these events.

On the night of Sunday, April 9, about 1:35 AM (Monday) the nearly full Moon passes very close to Gamma Virginis, a close double star. By moving south, you can see a grazing occultation. The northern limit of the graze zone passes approximately through Interstate 17 and the 101 freeway. From central Phoenix the star disappears at 1:33 AM and reappears at 1:43 AM.

On Monday, April 10, at 6:40 PM the full Moon rises spoiling any chance of hunting for faint fuzzies for the night.

On Sunday, April 16, from 7:05 PM to 9:55 PM, Europa or its shadow is on Jupiter.

On Tuesday, April 18, the Moon is at third quarter phase and rises at 1:32 AM (Wednesday).

On Sunday, April 23, from 9:20 PM to 12:31 AM (Monday), Europa or its shadow is on Jupiter.

On Tuesday, April 25, from 8:16 PM to 10:51 PM, Io or its shadow is on Jupiter.

On Wednesday, April 26, it is new Moon and you have all night to hunt for faint fuzzies.

Are you ready to observe a daytime occultation of a bright star? On Friday, April 28, at 9:02 AM, the Moon occults Aldebaran. The star reappears at 9:50 AM. The Moon is only 30 degrees from the Sun so be sure you don’t point your telescope toward the Sun as you hunt for the Moon. The Moon is down and to the left from the Sun.

On Sunday, April 30, between about 7:45 PM and about 10:00 PM, it is a good time to look at the craters Atlas and Hercules on the northern part of the Moon. Not only is the terminator well placed but libration tips that part of the Moon toward us. You might also want to look at the smooth floor, dark crater, Endymion, located between the pair of craters and the limb. (The area is almost as well presented on April 1, no fooling.)