Title: April Skywatch Highlights
Location: Hawaiian Islands
Date / Time: April 2011
Comments: Our "star attraction" for April is not a star at all. The planet SATURN, and it's spectacular ring system, offer quite the display this month. Saturn reaches opposition ? the point in it's orbit when it lies opposite the Sun, & thus brightest in our skies ? on the night of April 3/4. In early April, Saturn will rise in the east at sunset, be high overhead at midnight, and set at dawn. At opposition, the ringed planet lies a MERE 800 million miles from Earth ? it's closest approach of the year, so it shines brighter and appears bigger & more detailed through a telescope. And Saturn's rings now tilt at 9-degrees from our line of sight, affording wonderful views of their various features all month. Saturn lies in the constellation Virgo, & appears approx. 10 degrees directly above Spica, Virgo's brightest star. Saturn shines at magnitude 0.4 which makes it slightly brighter than Spica, and a bit fainter than Arcturus (Hokule'a), which appears approx. 30 degrees to the planet's left. Notice the color contrast between golden Saturn, blue-white Spica, & yellow-orange Arcturus. Dazzling VENUS is that blazing light you see in the early morning sky before dawn. At magnitude minus -4.0, there is no mistaking Venus for any other celestial object. Throughout the month, Venus rises in the east at around 4:40 AM, & is visible for about an hour before daybreak washes it out. JUPITER returns to the morning sky at the end of April. Look for the gas giant around April 30th, rising in the east at about 5:10AM, approx. 10-degrees below Venus. You'll have only about 30 minutes to spot Jupiter before it is "washed out" by the rising Sun, although at magnitude minus -2.0, it is still recognizably quite brilliant. Both MERCURY, and MARS join the morning sky planet line-up in the last ten days of April. Both planets appear in between Venus & Jupiter, but are much fainter than these two brilliant planets. While Mercury & Mars will be difficult to spot with the naked eye, they should be easily visible in binoculars. The 2 planets appear within 2-degrees of each other on April 21st, & rise together at around 5:20 AM. On the morning of April 30th, look for a beautiful "gathering of planets," in the eastern predawn sky. On that morning, at around 5:15AM, the crescent Moon will be above Venus; Mercury will shine at magnitude 0.95, just below Venus; Jupiter (mag. minus -2.0) will appear even further below Venus; & faint Mars will appear less than 1/2 a degree above Jupiter. You might need a pair of binoculars to spot Mars. The Southern Cross (Crux) rises in the southeast around 10PM in early April, & by 8PM at the end of the month. To view Crux, you'll need an unobstructed view to the southern horizon. Acrux, the bottom star of the Cross, rises only about six degrees above the horizon at it highest point. The Cross stands upright, & nearly due south, at 12:30AM in early April, & at 10:30PM at month's end. Look for 2 bright stars low in the south, Alpha & Beta Centauri, which point to the Roman-style "cross" asterism to their right (west). Note that the Hawaiian Islands are located at one of the few latitudes from where we can see all the way from the North Star, Polaris (Hokupa'a), to the Southern Cross, a Polynesian navigational "star line" called Ka Iwikuamo'o, "The Backbone." For an April Hawaiian sky map, visit Bishop Museum Planetarium www.bishopmuseum.org/planetarium (bishopmuseum.org).

Maintained by Roz Reiner - Kauai, Hawaii

 

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