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Post Info TOPIC: April 2011


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April 2011
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Mercury: at magnitude 2.3, starts the month in the constellation of Pisces. Best seen from 20.4h -21.2h. Mercury is at inferior conjunction on the 9th, (2.4° separated from center of Sun). Mercury is in conjunction in RA with Jupiter (3.5° separated) on the 10th. Mercury makes its closest approach to the earth (0.579 AU, magnitude 4.5), at 5:50 GMT, 13th April. Mercury is close to Mars (37.2')  at 19:20 GMT, 19th April. Mercury is at aphelion (distance to sun: 0.467 AU) on the 29th April.
(On April 1st,RA= 1h23m46s  Dec=+12°23.6' (J2000) Distance=0.676AU  Elongation= 13°   Phase k=9%  Diameter=9.9")

Venus: is a morning star of magnitude -4.0, The planet is in constellation Aquarius at the start of the month. It is best seen from 6.1h -16.0h. Venus is at Aphelion (distance to sun: 0.728 AU) at 0:40 GMT, 19th April, 2011. The planet is in conjunction in RA with Uranus (55.4' separated) at 19:52 GMT, 22nd April. The crescent Moon is 6º above Venus low in the eastastern morning sky on the 30th.
(On April 1st, RA=22h31m34s  Dec=-10°13.2' (J2000) Distance=1.260AU  Elongation= 35°   Phase k=80%  Diameter=13.2")

 Moon Phase Now!

Moon Phase Now!

Earth: The April Lyrids meteor shower is on the 23rd April.

The Moon: The New Moon is on the 3rd. This is the farthest new moon of the year. Lunar Apogee is at 10:15.7 GMT, 2nd April. This apogee is the 18th farthest of the last 1000 years, and the next 1000 years. Lunar Perigee is at 7:06.2 GMT, 17th April, 2011. The Full Moon (diameter: 33.305', declination: -14.66°) is at 3:44.0 GMT, 18th April. This is the second largest full moon of the year. Last Quarter Moon (declination: -15.92°) is at 3:46.9 GMT, 25th April, 2011. Another Lunar apogee (apparent diameter: 29'54.2") is on the 29th April. The crescent Moon is 5º below the Pleiades star cluster on the 6th.

Mars: at magnitude 1.2 starts the month in the constellation Pisces, and is lost in the glare of the Sun. The planet rises at 6:33.2 GMT on the 1st. The Moon is close to Mars, 1.2mag, Separation=5.56°, on the 2nd April, 2011. Mars is in conjunction with Uranus  (12.8') on the 3rd April. Summer begins in the southern Martian hemisphere on the 8th.
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Jupiter: is in the constellation Pisces. Jupiter is at conjunction on the 4th April, (only 1.1° separated from center of Sun). Mercury is in conjunction with Jupiter, 2.9° separated, at 4:59 GMT, 12th April.
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Saturn: at magnitude 0.4 sits in the constellation Virgo. The planet is best seen from 20.0h - 6.4h. The planet is the brightest object in the constellation and worth a look through binoculars this month. Saturn's rings are tilted 9 degrees to our line of sight. Saturn is at Opposition on the 3rd; and will be 8.614 AU (804 million miles) from Earth, its closest point for 2011. Saturn rises in the eastern sky at sunset near to the  bright stars Arcturus and Spica. A near full Moon is close to Saturn at 4:15 GMT, 17th April.
(On April 1st, RA=12h55m36s  Dec= -2°58.9' (J2000) Distance=8.615AU  Elongation=176°   Diameter=19.2")


Uranus is in the constellation Pisces. Uranus at magnitude 5.9, has a bluish-green hue and appears 3.7 arcseconds wide. Venus is in conjunction with Uranus (only 51.1' separated) at 03:28 GMT, 23rd April.
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Neptune: is in the constellation Aquarius. 

Pluto is in the constellation Sagittarius (mag 14.1). Normally, a finder chart is necessary to help in identifying the 0.1" diameter dwarf planet. The dwarf planet is best seen from 19.4h - 5.3h. Pluto is stationary: Getting Retrograde on the 9th April.
(On April 1st, RA=18h30m52s  Dec=-18°44.2' (J2000) Distance=31.929AU  Elongation= 93°   Diameter=0.1")

The Sun enters the zodiac sign Taurus at 11:17 GMT,  20th April.



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Saturn is the star of our night sky in April. The ringed planet will reach opposition on April 4. That means it is opposite the sun in the sky, which is the best time to see the planet because it is also closest to Earth and biggest and brightest in the sky at that time. Saturn is at its brightest now in three years because its rings are tilted a little farther open at about 8 degrees.
The remaining four of the brightest planets are all in the morning sky now. Venus is the highest of the group, rising about one hour before sunrise. The other three planets are all extremely low and faint, and you will need binoculars to see them. Mars and Mercury will be less than one degree apart just 15 minutes before sunrise on the morning of April 19. By the morning of April 29, half an hour before sunrise, Mars and Jupiter will be about one degree apart, and Mercury will be halfway to Venus up and to the right.

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The derivation of the name (Latin Aprilis) is uncertain. The traditional etymology is from the Latin aperire, "to open," in allusion to its being the season when trees and flowers begin to "open," which is supported by comparison with the modern Greek use of "opening" for spring. Since some of the Roman months were named in honor of divinities, and as April was sacred to Venus, the Festum Veneris et Fortunae Virilis being held on the first day, it has been suggested that Aprilis was originally her month Aphrilis, from her Greek name Aphrodite (Aphros), or from the Etruscan name Apru. Jacob Grimm suggests the name of a hypothetical god or hero, Aper or Aprus.
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Highlights

From a very dark location at that time, look for the Zodiacal Light, a huge soft glowing column of light in the western horizon. It is the light of the Sun reflected off dust particles in the inner solar system. Its axis closely coincides with the ecliptic.

The Lyrids
On April 21 (16-25) The Lyrid meteor shower reaches maximum around midnight tonight, although the peak is broad enough that the number of meteors should be consistent until morning twilight. Although the Lyrids are considered a major shower, they produce a meteor only every 3 to 5 minutes, on average. The near New Moon won't compete with the shower. The Lyrids are named after the constellation of Lyra from which they seem to radiate. deep-sky objects to have been recorded by the ancients, being mentioned by Aristotle around 325 BC.

The Summer Triangle
The morning sky, before dawn, now provides a preview of summer evenings. 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 center. The ribbon of soft light that delineates our galaxy flows up from the south, through the Triangle, and then cascades toward the northern horizon.



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Meteor Showers

This month sees the arrival of the Lyrids and the Virginids. Neither shower is very intense, but they do provide you with examples of shooting stars with different speeds: the fast Lyrids compared to the slower Virginids.
The peak of the April Lyrids (from the constellation of Lyra, the Harp) is on the 22nd, 5::00 UT, when you could see a maximum of about 15 meteors an hour.
The Virginids are active until the 18th, peaking on the 11th with 10 meteors an hour. Unfortunately the light of a Full Moon will also washout most of the meteors.
Watch out for sporadic meteors. Their rates for the Northern Hemisphere are now reaching a plateau. Expect around 12 random meteors per hour during the morning hours

ShowerActivity PeriodMaximumRadiantVelocityZHR
  DateR.A.Dec.km/s 
Zeta CygnidsMar 27 to April 13Apr. 6295° 37442
Gamma Virginids Jan 25 to April 18Apr. 11 195° -04° 33 4.6
LyridsApril 19 - 25Apr22 23 UT271°+34°4915
Pi PuppidsApril 18-25Apr23110°-45° 18


-- Edited by Blobrana on Monday 28th of March 2011 03:48:47 PM

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april.jpg



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