May 2008 – updated May 26

Skywatchers’ Guide for May 2008

PLANETS

Saturn and Mars all lose altitude in our May twilight 2008 sky. This chart shows the western evening sky at around 9:15 p.m. during early May and 8:15 p.m. during middle May. The Moon is shown for May 8-12. Mercury, Mars and the Moon are shown in the bright western evening twilight at around 8 p.m. on May 6. Note: This sky chart is most useful throughout southern Canada, much of the United States and northern Mexico. Mercury, Mars and the Moon are shown in the bright western evening twilight at around 8 p.m. on May 9. Jupiter and the southwestern morning sky at 4:30-4:45 a.m. as seen from the Desert Southwest in the latter half of May. The Moon is shown for May 23 and 24. Note: This sky chart is most useful throughout the southern United States and northern Mexico. Mars passes in front of the Beehive Cluster: May 21-24

Special note: The Mars Phoenix Mission, led by The University of Arizona, successfully landed on the north polar region of Mars on Sunday, May 25, 2008! If you missed the Phoenix Mars Mission Landing Celebration at The University of Arizona on Sunday, May 25 click here for the latest information on this first University led mission to another planet.

May 2008 continues to be a very good time to see Saturn and its ring system as Saturn and Earth are not far from their closest approach back in late February, and Saturn doesn’t set until well after midnight (by 12:45 a.m. near the end of May). Saturn fades slightly to around a 0.7 magnitude star-like object in May, making the ringed planet dimmer this year (compared to previous years) because its rings are more edge-on. Saturn is found high overhead in the constellation Leo the Lion during the convenient evening hours (well placed for telescopic viewing). Saturn resumes eastward or ‘direct’ motion on May 3, drifting farther (from two to three degrees) from Leo’s brightest star Regulus this month. With Saturn directly 90 degrees east of the Sun in our sky on May 22, May and early June are excellent times to see the shadow Saturn casts on its rings. 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. Also, the the 8 day old waxing gibbous Moon (one day after first quarter) is near and above Regulus and Saturn in our sky on Monday May 12.

Mars is visible starting 30 minutes after sunset this month conveniently high in the western sky in evening twilight. However the Red Planet continues to shrink in apparent size (from 5.7 to 4.9 arc seconds) and fades from magnitude 1.0 to 1.5 by the end of May as Earth recedes from Mars in space. Thus it is too small for viewing Martian surface contrast features, even in large, high quality telescopes at high power. Mars is currently visible when it is high in our northern hemisphere sky. Mars continues its eastward movement, creeping out of the constellation of Gemini, the Twins and through dim Cancer, the Crab. Mars is nearest (over five degrees) to equally bright Pollux (Gemini’s brightest star) in early May, but drifts 0.5 degrees per day away from Pollux and into Cancer. Look for the thick waxing crescent Moon below (west of) Mars in our sky on Friday evening May 9, and above (east of) Mars on Saturday evening May 10 (one day before first quarter moon). The Mars Phoenix Mission, led by The University of Arizona, successfully landed on the north polar region of Mars on Sunday, May 25, 2008! If you missed the Phoenix Mars Mission Landing Celebration at The University of Arizona on Sunday, May 25 click here for the latest information on this first University led mission to another planet.

Mars and the Beehive Cluster
It’s usually very difficult for a novice to detect the motion of a planet in the sky compared to the background stars. However sky-gazers get a prime opportunity from May 21-24 as the Red Planet, already moving half a degree in our sky per day, passes in front of the Beehive cluster, making for a very interesting sight in binoculars, or a wide-field telescope at low power. The bright Beehive Cluster is located in the faint zodiacal constellation, Cancer the Crab. Cancer is so faint that the Beehive, a prime target for binocular star gazing, can be a challenge to the novice. However with Mars found in front of (or very near the Beehive) for so long even a novice can easily find this bright star cluster. Starting near the end of evening twilight (at around 8:45 p.m. MST for the Desert Southwest), look well up in the western sky, almost directly above the western horizon to find Mars. From May 21-24 the Beehive will provide a dramatic starry backdrop for Mars. After this date in May scan below Mars in binoculars to find the Beehive. When observing the two, think of the distances that separate them and the Earth: Mars will be about 172 million miles away, while the Beehive will be 500 light years (or 3000 trillion miles) distant. Even at this distance the Beehive is still relatively close to our solar system in the Milky Way galaxy we reside in.

Mercury continues its best evening apparition this year and is easily visible above a clear west-northwestern horizon from early May until around May 20, starting 30 minutes after sunset. Mercury is brightest during the first few days of May and creeps higher in the evening sky but in early May is lower above the west-northwestern horizon than later in the month. Observers in most of the continental United States (including mid-northern latitudes) can see bright Mercury at over 5 degrees above the western horizon in early May (at around magnitude -1). Mercury is highest from May 6 through May 18 and is farthest from the Sun in our sky (at greatest elongation) on May 13. Throughout May the elusive world fades slightly each evening but after May 18 Mercury fades rapidly and becomes a binocular object in twilight for the last week of May. Also look for the thin waxing crescent Moon above Mercury in our sky on Tuesday evening May 6. 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.

Bright Jupiter is rising around 12:30 a.m. in early May, but well before midnight by middle May and by 10:30 p.m. by the end of May above the southeastern horizon. The gas giant world is highest each morning in May in the southern dawn sky. The giant planet is easily seen over 30 degrees above the southern horizon (as seen from the southern United States), around one hour before sunrise throughout the month of May. Whitish Jupiter is east of the Teapot of Sagittarius and is the brightest star like object that is well up in the morning sky. The waning gibbous Moon slides well below Jupiter in our sky on Saturday morning of May 24.

The brilliant planet Venus is lost in the glare of the Sun until it reappears at the end of August.

Visitors to Flandrau’s 16-inch telescope should note that Mars and Saturn are both visible in the telescope during public hours. 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 even Mars this month, note that they may appear to twinkle somewhat; however, this twinkling is of a slower nature than that of the bright stars.

MAY EVENING STARS

The northern sky at 9:45 p.m. in early May, and at 8:45 p.m. in middle May. Find Polaris, the North Star off the pointer stars of the Big Dipper. This star chart is most useful throughout the southern United States and northern Mexico. Looking east and overhead at 9:45 p.m. in early May, at 8:45 p.m. in middle May. This star chart is useful for the entire United States. 'Arc to Arcturus' and then 'speed on to Spica' off the handle of the Big Dipper. The Milky Way and southern sky as seen looking towards the south horizon in early May at 3:15 AM. This star chart is most useful for the southern half of the United States and northern Mexico. The eastern sky and the radiant of the Eta Aquarid Meteor Shower is shown for May 5/6 at 4 a.m.

Face west in May, 1 hour after sunset, to see the bright winter constellation Orion, the Hunter, and his hunting dog, Canis Major, still visible in spring evenings. In its middle is a horizontal row of three stars, Orion’s Belt. The belt points left to the bright star Sirius. Orion, Canis Major and Taurus set early and are all progressively lost in the glare of the Sun during May.
Turn around to face north and look high up to view the famous Big Dipper twinkling upside down. The Big Dipper is part of the larger constellation, Ursa Major, the Great Bear. It forms the bear’s hindquarters and unnaturally long tail. In England the Dipper is called the plow, even today! The star at the bend in the Dipper’s handle is named Mizar, for “the horse”, but the original Arabic name was the “girdle”. If you have normal (or well-corrected) eyesight and a clear sky, Mizar can be seen to have a faint, very close companion star, Alcor, whose name now means “the rider”. In ancient times it was often called “the test” as it was used to test eyesight. Since then the star may have brightened somewhat, because it is now no longer truly a difficult naked eye object. Binoculars help to easily distinguish Mizar and Alcor.

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’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 will 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.

The Milky Way Prominent in the Late Night Hours!
The Milky Way, the galaxy of stars, gas and dust our solar system resides in, is prominent all summer long, and rises in the early May morning sky after 1 a.m., but earlier, by 11 p.m. in late May. To see it, you’ll need to get away from city lights to a dark location, and look on a night when there’s not much interference from the moon. The Milky Way will appear as a “cloudy” band clear across the sky. High power binoculars and telescopes reveal the Milky Way to be clouds of stars, millions of them, with attendant star clusters and gas clouds making up some of the “fuzzier” spots you’ll see.

Eta Aquarid Meteor Shower Visible!
Although better observed from the Southern Hemisphere, the Eta Aquarid meteor shower is visible in early May after 2 a.m. and until dawn. This year the thin waxing Moon does not interfere with viewing, making it a good year to see this pre-dawn shower. The Eta Aquarid meteors are particles from Halley’s Comet, and have a sister shower in October, called the Orionids, after the constellation Orion. To see the shower simply sit outside in a reclining lawn chair, far away from city lights, face towards the southeastern horizon and look overhead. At the shower’s peak, around 3 to 4:15 a.m. on Monday morning May 5 you can typically expect to see up to 15 meteors an hour from dark sky locations, and around 10 meteors an hour from suburban Arizona skies, away from the glare of artificial lights. Some observers may see less than this count while experienced astronomers may see upwards of 30 meteors an hour from dark sky locations far away from city lights. If you miss Monday morning, then Tuesday morning May 6 is also expected to be fairly good.

MOON PHASES

The new moon in May occurs on Monday May 5. The May first quarter Moon will occur on Sunday evening, May 11. The May Full Flower Moon rises on the evening of Monday, May 19 and sets on the morning of Tuesday, May 20. The May 2008 last quarter Moon will occur on Tuesday morning May 27.

These dates and times are for southern Arizona, and are not necessarily Greenwich Mean Time dates, the moon phase dates used for calendars.

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