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Post Info TOPIC: May 2009


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May 2009
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Galaxies and planets are on the menu this month. All planets are visible (even Pluto), though not at the same time. Saturn presents the finest view for small telescopes as it hovers under Leo. And those of you with a good-sized telescope and dark sky can hop the galaxy fields of Virgo, between the stars Denebola in Leo and Vindemiatrix in Virgo to see the nearest major cluster of galaxies to the Milky Way (more on that in the next issue). Also, in mid-month, if you get up early you can see a double transit of Jupiter

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On the 1st May, 1949, Nereid the second moon of the planet Neptune was discovered by Gerard Kuiper.

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May has only one major meteor shower.
The Eta Aquarids (ETA) are the debris trail from Halley's Comet, which last passed through the inner solar system in 1986. The comet has an orbital period of about 76 years, and on May 5th we pass closest to Halley's orbit. At their peak the Eta Aquarids may produce up to 30 meteors per hour, from a radiant located at 22:12 (333) -04. This area of the sky is located in northern Aquarius, four degrees south of the third magnitude star Sadalmelik (Alpha Aquarii). The best time to view this activity is just before the start of morning twilight, when the radiant lies highest in a dark sky. However, from far Northern latitudes the the radiant is situated very low in the sky. With an entry velocity of 66 kilometres per second, a majority of these meteors will appear to move swiftly and produce a high percentage of persistent trains. You can listen to them by tuning to the 67 MHz meteor radar in Roswell, NM.

Shower Activity Period Maximum Radiant Velocity ZHR
Date R.A. Dec. km/s
Eta Aquarids April 21-May 12 May 5 338
-01 66 40- 85
Epsilon Aquilids May 4-27 May17/18 284.1 +15.5 30 5
May Librids May 1-9 May 6/7 229 -16 18
Eta Lyrids May 3-12 May 8-10 292 +40
N. May Ophiuchids April 8-June 16 May 18/19 253 -15 20 2-3
S. May Ophiuchids April 21-June 4 May 13-18 252 -23 40 5



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The celtic festival of Beltane is on May 1st.

North American Nebula
this is an enormous and vivid cloud of gas and dust which has striking resemblance to North America. Due to its large size (four degrees across, eight times the angular size of the Moon), the nebula ("NGC7000") must be viewed with low power instruments such as richest field telescopes or binoculars. Located in Cygnus the Swan, it rises in the east in the early evening on this date and becomes an easy object by 11:00 PM. For a relatively faint patch such as this a dark moonless sky is going to be necessary. First look for it with the naked eye. If you can't find it that way, try sweeping across the area with your binoculars.
Behind the nebula lies the part of the Milky Way. Photographs will show a million dancing fiery lights all splashed wildly across the ebony sky.
Deneb is thought to be the illuminating star, at about 70 light years away. The cloud is itself about 45 light years across.

The Summer Triangle -- Vega, Deneb, and Altair -- holds the central position, high in the south. The scorpion sits low to the south and slightly west. Directly to the arachnid's east is Sagittarius, the Archer, and between the two lies the direction toward the Milky Way galaxy's centre. The ribbon of soft light that delineates our galaxy flows up from the south, through the Triangle, and then cascades toward the northern horizon.

Bootes, the Herdsman
As May heads into June, the precession of Greek character continues across the evening skies. This evening you will likely see Bootes, the Herdsman, rising high in the heavens.
Bootes is believed to have been Arcas the illicit son of Zeus and Callisto, the daughter of Arcadia. Callisto was the favourite hunting partner of the goddess of hunting, Artemis. Zeus wanted Callisto and succeeded by assuming the appearance of Artemis one day. When it became clear to the real Artemis what had happened, she banished her friend from her company.
After Callisto gave birth to her son, Arcas, the wife of Zeus became angry at her husband's indiscretions. Cursing her, she changed her rival into a bear and condemned her to wander the forest for years to come. Years later Arcas himself became an accomplished hunter and stumbled across this bear in the woods. At that point, Zeus stepped in and sent the both of them into the heavens where Callisto was turned into Ursa Major and her son Arcas, Bootes.
In another legend Bootes was identified as Icarus, the inventor of wine. One day he gave some wine to a few clueless shepherds. Mistaking their drunken state for being poisoned they, killed him. Maera, his dog ran home and returned with Erigone, the daughter of Icarius who upon seeing her dead father committed suicide along with the dog. Taking pity on them, Zeus immortalized them in the heavens for all eternity. Maera became Canis Minor, Erigone is now seen as Virgo, and Icarius of course is Bootes.
The constellation is best known for housing Arcturus, the fourth brightest star in the sky .

Coma Berenices
Rising in the eastern skies about mid-evening is the faint constellation, Coma Berenices, "Berenices' Hair". Undistinguished as it seems, this constellation has one significant feather in its cap : this is where the North Galactic Pole (NGP) is located in between stars Beta and Gamma. The galaxy like everything else in the Universe rotates around on an axis. Where the Earth spins every 24 hours, our galaxy takes about 20 million years for each rotation and the NGP is where the North Pole of the galaxy is aimed. The southern Galactic Pole is located in Sculptor. Since you are looking away from the galaxy you will see fewer bright stars than toward the body the Milky Way. But now you have a clear shot into extra galactic space revealing all many more galaxies which would otherwise be hidden by our own.
While Coma Berenices is one of the more modern constellations (being created in 1551), the grouping was mentioned on occasion by the ancients. Frequently referred to both as the "hair" of either Ariadne or Queen Berenice of Egypt. Unlike most constellations this is one of the few that refers to a real person.
Berenice married her brother, Ptolemy III (as was Egyptian royal tradition) in the third century BC. A few days after her marriage Ptolemy went off to war. She promised him that if he were to return safely she would cut off her hair. He did, and so she did, placing it in the temple as a gift to the gods. The next day her hair mysteriously was gone, gone to the stars according to the court mathematician.
While dim in stars, Coma Berenices is a very fertile playground for astronomers, containing about half of the famous Coma-Virgo galactic cluster. So it has many fine galaxies well within the grasp of amateur telescopes.

Notable Messier objects

M13 in the constellation Hercules, is one of the largest of over 100 globular clusters in our Galaxy. Located about 25,000 light-years away, it contains about half a million stars packed into a space only a few tens of light years in diameter. Globular clusters contain some of the oldest stars in the Universe.
M56Also in the constellation of Lyra we find our first globular cluster of the night. In a telescope look for a small round ball of light, slightly brighter in the centre. This is a difficult binocular object appearing as a small fuzzy patch.
M27Also known as the Dumbbell nebula, the largest planetary nebula in the Messier Catalogue, M27 lies in the constellation Vulpecula. Fairly easy to see in binoculars as a small hazy patch. In small to medium scopes it appears as a rectangular patch of light. In large scopes it may even appear round in shape with a bright rectangular, or dumbbell shaped core.

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May marks the first time in a long time that it will be possible see all of the planets during the course of one month. However, you will not be able to see them all during one night and you will need a telescope to see some of the outer planets.
Tiny Mercury will still be visible at 10 degrees above the western horizon about a half-hour after sunset during the fist four evenings of May. After that it will be lost to us for the rest of the month as it swings through inferior conjunction (between us and the Sun).

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By midweek the moon interferes with early evening dark sky views and by the weekend, nearly the whole night. The moon though is a fascinating object and always worth exploring. You can still view Mercury and Saturn in the evening sky and Jupiter, Mars, and Venus in the morning sky as dawn breaks. No good passes of the ISS this week for us in the Denver area either. Moonlight will interfere with comet hunting and observing meteor showers this week and next. I added a new 'astro hints' section about a cheap way to clear corrector plates and diagonals of dew and frost.

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Sky watchers looking in the pre-dawn skies of May will get to see a most amazing planetary line up.
The planets Venus, Mars, Jupiter, Uranus and Neptune will span a 40-degree area of the sky. As the month of May moves on, viewers will get to see a great conjunction with the Moon, Venus and Mars low in the eastern sky on the morning of May 21.

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Mercury is sinking into our evening twilight to leave Saturn as our only bright planet for much of the night. The ringed world falls from our mid-southern sky to the WSW by our map times. Meanwhile, Arcturus replaces Saturn as the brightest object in the S as the Plough topples westwards from the zenith and the Summer Triangle formed by Vega, Deneb and Altair starts to climb in the E.

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Fifty years ago on May 28, two rhesus monkeys, Able and Baker, were launched on a suborbital flight from Cape Canaveral. Two years later (on May 5), astronaut Alan Shepard took a similar trip.

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