March 2008

Skywatchers’ Guide for March 2008

PLANETS

Mars, the Moon and the evening sky at the end of evening twilight. This sky chart is most useful for the southern USA and northern Mexico. Saturn, the Moon and the evening sky facing east near the end of evening twilight in middle March 2008. This sky chart is most useful for much of the USA and northern Mexico. Jupiter, the Moon and the morning sky as seen facing southeast near the start of morning twilight at 5:30 a.m. in early March 2008. This sky chart is most useful for the southern USA and northern Mexico. Jupiter, the Moon and the morning sky facing southeast near the start of morning twilight at 5:20 a.m. in late March 2008. This sky chart is most useful for the southern USA and northern Mexico. The Moon, the planets Venus, Mercury and Jupiter are shown as seen facing southeast during morning twilight at 6 a.m. in early March 2008. This sky chart is most useful for the southern USA and northern Mexico.

March 2008 is a great time to see the Saturn and its ring system as Saturn and Earth are near their closest this year, and Saturn will be up nearly all night long. Saturn brightened to a zero magnitude star-like object (at magnitude 0.2) by its opposition date on February 24 (when it is opposite from the Sun in the sky and rising at sunset), and will dim slightly in March.

Saturn rises earlier each night in the constellation Leo the Lion and is high overhead in the convenient evening hours (well placed for telescopic viewing). 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 drifts nearer to (from five to three degrees to) Leo’s brightest star Regulus this month. The ringed planet is dimmer this year compared to previous years because its rings are more edge-on. Also, the waxing gibbous Moon is nearest Saturn (and Regulus) in our sky on Tuesday evening, March 18.

Mars is conveniently high overhead in evening twilight, and is well placed for typical sharp telescopic viewing (the higher the altitude, the less air is being looked through). However Mars shrinks in apparent size from 9 to only 7 arc seconds in March as Earth recedes from Mars in space (really too small for viewing of surface contrast features, even in large, high quality telescopes at high power). Mars is currently visible starting 30 minutes after sunset when it is overhead in our northern hemisphere sky. During the month Mars fades from a fairly bright magnitude +0.2 (or as bright as Saturn) to a less bright +0.6. Mars accelerates its eastward movement, creeping through the constellation boundary of Gemini, the Twins. Look for the waxing gibbous Moon near Mars in our sky on Saturday evening of March 15. The Mars Phoenix Mission, led by the University of Arizona, is en route to Mars with arrival on the north pole of Mars on Memorial Day weekend, 2008; For information on this first University led mission to another planet, click here.

Bright Jupiter gains altitude each morning this March in the southeastern sky. By the end of March the giant planet is easily seen almost 30 degrees above the southeastern horizon one hour before sunrise (from the southern United States). Jupiter is east of the Teapot of Sagittarius and is the brightest star like object that is well up in the morning sky (much brighter Venus is very low and difficult to see). The waning crescent Moon slides well below Jupiter in our sky on the mornings of March 2-3 and March 30.

In early March 2008 the brilliant planet Venus is sinking into the glare of the Sun and is very low in the morning twilight sky. By the start of March Venus is only a few degrees above the east-southeast horizon about an hour before sunrise and is grouped with much fainter Mercury. During the first week of March, brilliant Venus can be seen in a clear sky (with an unobstructed eastern horizon) grouped loosely with Mercury starting around 1 hour before sunrise. The two are only about 3 to 4 degrees above the east-southeastern horizon at 6 a.m. for the Desert Southwest. The first spacecraft to orbit Mercury, the MESSENGER spacecraft arrived early this year in its first flyby of Mercury. For a link to see the latest images, and find details about the MESSENGER spacecraft, and the Mission Operations Center click here.

Visitors to Flandrau’s 16-inch telescope should note that Mars is visible in the telescope during public hours 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 this month, note that it may appear to twinkle somewhat; however, 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 Wednesday March 19
(March 20 for East Coast)
On Wednesday March 19, at 10:49 p.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. This Spring Equinox occurs at 1:49 a.m. (Eastern Time Zone) on March 20 for those areas of the East Coast of the United States.

MARCH EVENING STARS

The March western evening sky at around 90 minutes after sunset as seen on moonless nights far away from city lights in the southwestern United States. Note: This sky chart is most useful throughout the southern United States and northern Mexico. The Big and Little Dippers and the northern sky at 8:30 p.m. in middle March. ‘Arc to Arcturus’ off the handle of the Big Dipper. This sky chart is useful throughout the United States, southern Canada and northern Mexico. The northeastern sky in March at around 10:45 p.m. in early March, at 9:45 p.m. in mid-March and at 8:45 p.m. in late March as seen from the southern U.S. ‘Arc to Arcturus’ and then ’speed on to Spica’ off the handle of the Big Dipper.

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 a not very bright star, but it’s in a dim part of the sky where there’s 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 new moon in March occurs on Friday March 7. The March first quarter Moon will occur on Thursday evening, March 13th. The March full moon is called the ‘Worm’ Moon by native Americans and rises on the evening of Friday, March 21 and sets on the morning of Saturday March 22. The March 2008 last quarter Moon will occur on Saturday morning March 29th.

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.

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