March 2009

Skywatchers’ Guide for March 2009

HIGHLIGHTS: Venus, whose phase becomes an increasingly large crescent, continues to be especially prominent early this month as our evening planet (the ‘evening star’) above the west-southwestern horizon. Although Venus quickly loses altitude this month, and moves into the glare of the Sun, its crescent phase will be a spectacular sight in a telescope. Saturn, at the opposite end of the sky in the west, is at opposition on March 8: Join Flandrau for free viewing of Saturn, Venus and the Moon on Friday March 6 and Saturday March 7 from 6:30 – 9:30 p.m.

PLANETS

The evening sky on March 1 and March 15 at around 45 minutes after sunset facing west. The eastern sky on March 8-10 at around 8:30 p.m. This sky chart is most useful for the entire United States, southern Canada and northern Mexico. The morning sky on March 22-23 at around one hour before sunrise facing east-southeast. Binoculars may be needed to spot Mars. This sky chart is most useful for the continental United States and northern Mexico.

March 2009 is a great time to see Saturn and its ring system as Saturn and Earth are near their closest this year, and Saturn will be up nearly all night long.  The rings of Saturn now appear razor thin, as we view them edge-on from Earth, and are now near the thinnest we can see them conveniently in the evening for years to come. Saturn brightens to a zero magnitude star-like object (at magnitude 0.5 and 19.7 arc seconds across) by its opposition date on March 8 (when it is opposite from the Sun in the sky and rising at sunset). Day by day Saturn rises earlier in our sky and is high overhead in the convenient evening hours (well placed for telescopic viewing). The best views of any planet should be when it is highest in the sky, but viewing is dependent on atmospheric stability and conditions, and of course, the quality and size of the telescope used. Large, high quality amateur telescopes in good “seeing” (stable atmospheric conditions) will best reveal any features on a planet’s disk. Saturn is located in the constellation Leo the Lion, well below and east of its bright star Regulus, which is the bottom of the star pattern called the ‘sickle’ of Leo. The 17-day-old waning gibbous Moon is found well below and nearest Saturn in our sky on Wednesday morning, February 11. Also, the waxing gibbous Moon is nearest Saturn (and Regulus) in our sky on Tuesday evening, March 10.

The brilliant planet Venus starts March still well up in the western sky, but quickly sinks into the glare of the Sun by the end of March. As it does so its crescent phase narrows and becomes larger as Venus moves closer to Earth. Its crescent phase will be a spectacular sight in a telescope and may even be spotted in good quality binoculars. Venus quickly loses altitude this month, and moves into the glare of the Sun during the last 10 days of March. By the start of March Venus is over 20 degrees above the western horizon about an hour after sunset. Join Flandrau for free viewing of Saturn, Venus and the Moon on Friday March 6 and Saturday March 7

Mars is a difficult and faint object in the morning twilight and starts the month grouped tightly with brighter Mercury: the two are only 0.4 degrees apart on March 1, but are very low, only 3 degrees above the east-southeastern horizon 35 minutes before sunrise. Because the two are so low in bright twilight, you’ll need binoculars to spot them in a clear unobstructed horizon. Afterward Mercury will then continue to brighten but lose altitude and move into the glare of the Sun. Faint Mars will be easier to find by the end of March when it moves higher in the twilight sky: Use the Moon to find it on the morning of Tuesday March 24, as Mars will lie closest to the Moon in our sky on that date.

Bright Jupiter gains altitude each morning this March in the southeastern sky. By the end of March the giant planet is easily seen almost 15 degrees above the east-southeastern horizon 45 minutes before sunrise (from the southern United States). Jupiter is located in the constellation of Capricornus, the Sea Goat and is the brightest star like object that is well up in the morning twilight. The waning crescent Moon is closest to and above (west of) Jupiter in our sky on the morning of Sunday March 22.

Visitors to Flandrau’s 16-inch telescope should note that Venus is visible in the telescope only early in the month at around 7-7:30 p.m. while Saturn is visible earlier each night. Saturn is visible after 8 p.m. on March 1st but by 7:00 p.m. on March 12. Flandrau’s 16-inch telescope is open for viewing during public hours, weather permitting, Wednesday through Saturday nights (excluding select holidays), from 7-10 p.m.

Finally, remember that in spotting planets there is a general rule: ’stars twinkle, planets don’t’. This is because stars are point sources of light; therefore starlight is easily disturbed and shifted by air currents in the Earth’s atmosphere. However when looking at Mercury or Mars this month, note that they may appear to twinkle somewhat; This twinkling is of a slower nature than that of the bright stars.

Zodiacal Light Visible
March is an excellent month, and Arizona is a superb place, to look at the Zodiacal Light in the western evening sky, starting 75 minutes after sunset. The Zodiacal Light is sunlight reflecting off of meteoritic dust in our solar system. Because this dust lies along the plane of the solar system, we see its faint glow as a cone of light along the constellations of the Zodiac. Often confused with light pollution or twilight, the Zodiacal Light must be seen on clear moonless nights, in dark locations far away from city lights. In March look for the faint colorless cone shaped glow of the Zodiacal Light to reach high up from the western horizon towards the Pleiades, or ‘Seven Sisters’ star cluster.

Vernal or Spring Equinox occurs on Friday March 20
On Friday March 20, at 4:45 a.m. MST (Mountain Standard or Tucson time), the sun crosses the celestial equator on its way north, marking the spring or Vernal Equinox. The sun on the equinox stands directly overhead from the equator at noon. The name Vernal Equinox means “green time of equal night and day”. Night and day on the equinox take essentially equal amounts of time for most parts of the world.

Comet Lulin

Comet Lulin, discovered at the Lulin Observatory in China in 2007, has moved into the evening sky and will be visible in binoculars and good quality wide-field telescopes in March when it may be as bright as fifth magnitude. The comet was closest to the Sun on January 14, 2009 but passed only 0.41 AU (about 38 million miles) from Earth on February 24, 2009 (the comet will be brightest around this time into early March). The comet should be an interesting object for the public to view but will probably not be easily visible from city locations. However the Flandrau Observatory Hyperstar imaging system should easily reveal the tail of this comet and any anti-tail if visible, giving the best view (Comet Lulin will be dimmed by the nearby Moon during the special viewing events on Friday, March 6/7),

Comet Lulin will be visible (weather permitting) in the Flandrau Observatory (normally open Wednesday – Saturday) during March starting around 7:15 p.m. Moonlight will significantly hinder viewing of the comet from about March 2-3 through March 11th, when it will appear brightest this month (being closest to Earth for March). Starting March 12 at 7:00 p.m. the comet can again be seen without interference from moonlight.

MARCH EVENING STARS

Click on images to enlarge

The bright stars of winter still dominate the evening March sky, but shift to the western half of the sky early. Look for Orion, the Hunter, and his shimmering belt of “three stars in a row” to find other sights in the winter sky. Orange Betelgeuse, the shoulder of Orion the Hunter, shines upper left of Orion’s 3 glittering belt stars and blue white Rigel shines below. The Gemini Twins, the bright stars Castor and slightly brighter Pollux, twinkle left of Orion. Castor will be above Pollux. Take Orion’s belt and point down and left to Sirius, the brightest star in all the heavens. Sirius is the nose of the Greater Dog, Canis Major, a companion to Orion in the heavens. Later in the evening, Orion and his winter companions will set in the western sky. Orion’s belt will then point left to Sirius when in the western sky. Betelgeuse at that time can be found directly above Orion’s belt.

The Big Dipper is easy to find this March (and every March) in the northeast evening sky. Look for the Big Dipper high in the northeast 1-2 hours after sunset. Take the two ends stars off of the bowl (the Pointer stars Dubhe and Merak) and point to Polaris, the North or Pole Star. Polaris is a star of ordinary brightness, and marks the end of the handle of the Little Dipper. Polaris is a direct indicator of latitude and so is always found the number of degrees above the northern horizon equal to an observer’s latitude. In Tucson look for Polaris about 30 degrees (or 3 fists) above the northern horizon. Polaris stays put in the sky, so to the eye it doesn’t appear to move. This is because Earth’s axis is pointed toward Polaris in space.

The Big Dipper is an amazing signpost in the heavens, useful in finding many notable sights in the sky. The two stars forming the outside end of the Big Dipper’s bowl — the part opposite from the handle — are called “the Pointers.” A line drawn through them points quite near the North Star, Polaris. Polaris closely marks the north celestial pole, and hence appears not to move in the sky to the unaided eye. Polaris is also the end of the handle of the Little Dipper, whose other name is Ursa Minor, the Little Bear. Continue straight down from Polaris to the horizon to find true north. Polaris always remains at almost exactly the same point over the northern hemisphere landscape, day and night, and is always there to mark almost exactly due north. Polaris is not a very bright star, but it is in a dim part of the sky where there is nothing else to confuse it with. Come back to the Big Dipper and follow the curve of the Dipper’s handle back across the sky by about two handle-lengths and you’ll see the brightest star of spring, the bright yellow-white star Arcturus. Continue down from Arcturus to “spike” or speed onto the blue star of spring, Spica.

MOON PHASES
The March first quarter Moon will occur on Tuesday evening, March 3. The March Full Worm Moon rises on the evening of Tuesday, March 10 and sets on the morning of Wednesday, March 11. The March last quarter Moon occurs on Wednesday morning March 18. The March 2009 new moon will occur on Thursday, March 26.

Note: Additional information can be accessed by phone at Flandrau Science Center’s Astronomy Newsline at (520) 621-4310 or as a menu option at 621-S-T-A-R.

Graphics done using Starry Night Pro and Adobe Photoshop. To purchase Starry Night Enthusiast, go to http://StarryNight.com