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Post Info TOPIC: July 2011


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July 2011
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Mercury: at magnitude -0.4, starts the month in the constellation of Cancer.  The New Moon is close to Mercury at 21.15 UT, 2nd July. Mercury is at dichotomy/Half phase on the 16th July. Mercury is at Greatest Elongation (26.8° East) on the 20th July. Mercury is at Aphelion on the 26th July.
(On July 1st, RA= 8h07m15s  Dec=+22°00.8' (J2000) Distance=1.139AU  Elongation= 20°   Phase k=73%  Diameter=5.9")

Venus: is a morning star of magnitude -3.9, The planet is in constellation Taurus at the start of the month. It is best seen from 2.5h -20.1h. The Moon is close to Venus at 8.40 UT, 30th July.
(On July 1st, RA= 5h42m57s  Dec=+23°09.6' (J2000) Distance=1.677AU  Elongation= 13°   Phase k=97%  Diameter=9.9")

  phase.gif


Earth: is at Aphelion, furthest from Sun, (1.017 AU, 152,102,197km) on the 4th July

The MoonThe New Moon is on the 1st and the 30th July. Lunar Apogee is at 22:43.8 UT, 21st July.  Lunar Perigee is at 13:49.6 UT, 7th July. The First Quarter Moon is on the 8th June. The Full Moon is at 06:39.6 UT, 15th July. Last Quarter Moon is at 05:01.9 UT, 23rd.

Mars: at magnitude 1.4 starts the month in the constellation Taurus.
(On July 1st, RA= 4h20m21s  Dec=+21°22.5' (J2000) Distance=2.224AU  Elongation= 32°   Phase k=96%  Diameter=4.2"   planetographic latitude of the Earth=-7.1°)

Jupiter: is in the constellation Aries. At magnitude -2.3, the planet is best seen from  0.5h - 2.8h. The Moon is close to Jupiter at 23.45 UT, 23rd July.
(On July 1st, RA=2h11m35s  Dec=+11°59.8' (J2000) Distance=5.313AU  Elongation= 64°   Diameter=37.1")

Saturn: at magnitude 0.9 sits in the constellation Virgo. The planet is best seen from 22.3h - 0.1h. The Moon 8° S of Saturn on the 8th July.
(On July 1st, RA=12h42m40s  Dec= -1°52.9' (J2000) Distance=9.552AU  Elongation= 92°   Diameter=17.3"   planetocentric latitude of the Earth=7.5°)


Uranus: is in the constellation Pisces. Uranus at magnitude 5.9, has a bluish-green hue and appears 3.7 arcseconds wide.  Uranus is stationary: Getting Retrograde on the 10th July
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Neptune: is in the constellation Aquarius. Neptune at magnitude 7.8, is Stationary: Getting Retrograde on the 3rd June, 2011.

Pluto: is in the constellation Sagittarius (mag 14.0). Normally, a finder chart is necessary to help in identifying the 0.1" diameter dwarf planet. The dwarf planet is best seen from 23.6h - 2.7h.
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The Sun enters the zodiac sign Leo at 04:12 UT, 23rd July. A partial solar eclipse will occur on July 1, 2011.



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Earth will be at aphelion, its furthest orbital distance from the Sun, around midnight on 3 July. It will then be 152,095,745 km from the Sun, compared with its minimum distance from the Sun (perihelion) of 147,103, 622 km in January.

Since the eccentricity of our planet's orbit is very small and the orbit is nearly circular, aphelion and perihelion differ from the mean Sun-Earth distance by less than 2%. If you drew Earth's orbit on a sheet of paper it would be difficult to distinguish from a perfect circle.
Since Earth is at its furthest from the Sun, average global sunlight arriving in July is about 7% less intense than it is in January. However, the average temperature of Earth at aphelion is about 2.3C higher than it is at perihelion - Earth is actually warmer when it is further from the Sun.

This is because our planet has more land in the northern hemisphere and more water in the south. During July - in the northern summer - the mainly continental northern half of our planet is tilted toward the Sun, and the land masses heat up more easily than the oceans.



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JULYROBOT.jpg



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Meteor Showers

July has three main meteor shower: the Capricornids are active over July with peaks on the 8th, 15th and 26th, although the maximum rate is only about 5 meteors per hour. The Delta Aquarids are active from 15 July with a peak on the 29th of 10-20 per hour. The Alpha Cygnids will peak on the 21st July when you can see up to 5 shooting stars per hour.

Shower Activity Period Maximum Radiant Velocity ZHR
  DateR.A. Dec. km/s  
Beta Taurids (daylight)June 5-July 18 29th June 79.4 °
21.2 °   
Capricornids8th8th July °  
July Phoenicids10th -19th July10th July    
Ophiuchids15th 15th July18.9h-22.6°13.4km/s5
Alpha Capricornids 16th July    
Perseids17th July - Aug 24th10-14 August    
Alpha Cygnids 21st July   5
Capricornids26th26th July    
Kappa Cygnids 27th July    
S. Delta-AquariidsJuly 14-Aug 1830th July3.9h-51.8d14 km/s11.2
Scorpius-Sagittariids 31th July20.2h-24.6°10.5km/s5


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Highlights
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.
Trifid and Lagoon Nebulas
By mid-month the distinctive "Teapot" of Sagittarius should be hovering above the southern horizon.
Looking towards the right of the lid of the teapot and a little to the right is the delicate Trifid Nebula, "M20". A nebula is simply a cloud of interstellar dust and gas, the raw materials that stars are made of. If there are already stars embedded in the cloud it will glow with an eerie ghostlike appearance forming such vistas as the Great Orion Nebula, or this one, the Trifid. Sporting two patches of nebulosity, one red the other blue, this is one of the finest objects in the sky and very easy to find in binoculars. Just slightly below M20, is the rosy red Lagoon Nebula, which goes under the profoundly less romantic name of "M8". This is one of the best diffuse nebulas for naked eye observers, surrounding the small young star cluster NGC6530. The nebula is known for having a number small dark globules of material believed to be stars at the very beginning of formation, sometimes called protostars. Overall M8 is over 100 light years across, with its central regions a more modest 50 light years in diameter. It is also one of the largest in the sky, challenging the full moon for size.
M51 The Whirlpool Galaxy
Summer is the time for the galaxies.
As the earth swings around in its orbit the night skies are aimed away from the centre of our own galaxy, the Milky Way. No longer does the body of the Milky Way block the skies, now we can look out into the depths of space. One of the most spectacular is M51, better known as the Whirlpool Galaxy located right below the handle of the "Big Dipper". This was the first ever to be seen as in the classic spiral form, in the mid-19th century. While visible in the smallest instruments, its twisted nature will not show in anything less than an eight-inch telescope. With a luminosity of 10 billion suns and a diameter of 100,000 light years, M51 is roughly equivalent to M31, the great Andromeda galaxy and in turn, our own home. The Whirlpool is about 35 million light years away and glows at a genial eighth magnitude. In the sky it is seen face on and is about 1/3rd of the visual width of the Moon. It should be visible as a dim fuzzy patch in a pair of binoculars in a very dark sky. If you are lucky in that regard, step outside and see what you can see tonight.
Notable Messier objects
M3 is one of more heavily studied globular clusters due to its position in the galaxy, putting it far above the interstellar dust and gas that dim its light. More than 200 variable stars have been observed out of a total of near 50,000. Being one of the brightest
globulars, M3 is regarded as one of the most striking in the sky. A 60mm scope will begin to reveal hundreds of its magnitude 11 stars, while larger instruments may show arms or branches radiating from the sides.
M5 : A Nice Globular Cluster
Located in the "head" half of the split constellation, Serpens, you will find the smashing globular cluster, M5. These are round, concentrated clusters of old stars which usually collect into halos surrounding galaxies. They contain between 100,000 to 10 million stars and are typically 100 light years across. Globulars are wonderful objects in small telescopes due to their perfectly rounded shape and the delicate glistening of the nucleus.
Omega Centauri in the southern skies is by far the best. northerners can relish M13 in Hercules, M3 and now M5, which are, considered one of the finest in the sky. It's 13 billion year age makes M5 one of the oldest clusters known. Easily visible in binoculars it takes at least a four-inch telescope to be able to resolve some of its ˝ million stars.


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