News Letter March 2013

The next meeting will be at Pedro’s Castle starting at 7:15 PM onwards on Thursday 14^th March. All are welcome and there is no charge for occasional visitors. Ring or email me if the weather looks bad and you are still intending on coming. Meetings are cancelled if there is more than 50 percent cloud cover.

“Red Sky at Night” on Saturday 23 February was a huge success, we estimated over 500 people visited “Astronomical Avenue” and it looks like we are back for next year too,

At the UCCI Observatory the telescope making course run by Bill finished with some good publicity.  Two of the scopes attended “Red Sky at Night” and performed really well

The “Introduction to Astronomy” course on Tuesday Evenings has one more week to go I write this newsletter .A follow up course at Easter has been promised, but again dependant on numbers. Last night (5^th March) whilst outside observing we were all surprised to see a bright meteor-like object cross the sky at around 8:45 PM. The object was very bright and lasted 3-4 seconds. Was this a man-made flare? It was difficult to say – If anyone else saw this object - other than the 15 people attending the course (!) let me know

So let’s move on to what’s going on this month –. Comet Pan-STARRS has been putting on a show south of the Equator but now its orbit takes it into the Northern Hemisphere.  The first easy chance to see the comet will be on March 12^th when the comet will be close by a near-new moon or why not come to the Society meeting on the 14^th?

Look to the West after sunset- it will not a bright object but with luck will be visible as a smudge in the evening twilight. Binoculars will help but please ensure the sun has safely set.

Those with Internet access go to http://www.skyandtelescope.com/observing/ataglance for a very simplified chart showing its visibility after sunset. The comet should be visible next month too but will be very much fainter.

The name of the comet is interesting. Only a few years ago, comets were discovered by keen amateur astronomers with no more than a pair of good binoculars. More recently – unless the discovery has been a lone non-professional astronomer, the discovery has been named after the telescope, or even more recently by networks of robotic telescopes. Pann-STARRS is such an array based in Hawaii designed to detect near-Earth objects, its funding is mainly from the US Air Force but also includes academic institutions world-wide including the UK and Germany.

 Interestingly we have another bright comet later this year – Comet ISON is named after another International network of telescopes – this one is predominantly Russian Federation (is there such a thing?) in funding but with input from other countries such as Switzerland and Spain (ok ,ESA) . Comet ISON will either be spectacle or a damp squib, who remembers Kohoutek?!!

Meanwhile there’s now a third comet which may reach naked eye visibly in April – although much less bright compared to the two already mentioned, it is photographically a very pretty (green) comet. Needless to say comet Lemmon is named after a telescope rather than a person.  However as traditionally comets were the bringers’ of doom and bad news, we should expect some media fall-out soon. For me I’ll quote the old bard Shakespeare himself

“When beggars die there are no comets seen;
  the heavens themselves blaze forth the death of princes."

Fingers crossed everybody.

Meanwhile let’s have a quick look at the night sky for around 15^th February 8 PM EST as seen from Spotts Beach, Grand Cayman. The chart below comes with the permission of Chris Peat who runs the excellent Heavens’ Above website (http://www.heavens-above.com) it’s also very good for predicting satellite crossings.

The chart shows Jupiter still high in the sky close to Aldebaran in Taurus the Bull. Orion is still easily visible too.  Look out for Leo (The Lion) rising in the East. Some three hours later at around 11 PM Leo will now be nearly overhead, and at this time it will be majestic Saturn rising in the East.

Society News can happen quickly so also check http://caymanastronews.blogspot.com/ and our Facebook page – although I’ve been so busy writing up the course notes for the Astronomy Class I’ve been neglecting things of late

Clear Skies Everyone Chris (925 7657) or cpcooke@aol.com

News Letter February 2013

The next meeting of the Astronomical Society will be at Pedro’s Castle starting at 7:00 PM onwards on Friday 15th February. All are welcome and there is no charge for occasional visitors. Ring or email me if the weather looks bad and you are still intending on coming. Meetings are cancelled if there is more than 50 percent cloud cover.




The Society has also been invited to a special event at this years’ Cay Fest called “Red Sky at Night” on Saturday 23 February. This is a paid event but there is free entry for anyone who wants to help the Society out. First come first served. We have a good dark spot and will be there from 8 PM till 10 PM, Let’s hope for clear skies!!



At The UCCI Observatory the Telescope making course run by Bill Hrudey on Monday Evenings is progressing well – in a month or so there could be seven 6 inch Dobsonian Telescopes ready for action. After much arm twisting (mine) the Introduction to Astronomy course on Tuesday Evening is proving to be a huge hit and was heavily oversubscribed. A follow up course at Easter has been promised.



The big news that will be in the press this month is of the close approach of an asteroid called 2012 DA14, at 2 PM EST on Feb 15th. This lump of rock is about 150 ft wide and about 130,000 metric tons in weight. At its closest approach will only be 17,000 miles from the Earth’s surface. If that seems along way “up” to you then consider that geostationary satellites that provide our satellite TV orbit at a height of 22,200 miles – so this takes the record for the closest known approach, for an object this size, though we are told by NASA we are quite safe (!) and that the chances of an object like this hitting the Earth are on average a mere once every 1,200 years.



The Star Chart below is taken from Chris Peats excellent website Heaven’s Above –. http://www.heavens-above.com. The site enables the user to produce a chart for the exact latitude of the observer. Many of the charts in Astronomical magazines and books – although of high quality and very readable aim for the latitudes where most of their readers live, certainly not for the Tropics. Here in Cayman we are privileged to be able to see many of the Southern Hemisphere stars which cannot be seen at higher latitudes.



The chart is for 8:30 PM on Friday 15th February as seen from George Town

Overhead along with a 5 day old moon there will also be seen a very bright “star” which is in fact the planet Jupiter. The imaginary line shown on the chart is called the ecliptic and the Sun, Moon and all the planets with the exception of Pluto follow this path. As is now well known Pluto was demoted few years ago to a “dwarf planet”. One of the several reasons for this is simply because it does not orbit the Sun in the same plane as the other planets.



When observing the sky at our latitude of 19 degrees North there are occasions when the ecliptic – and hence the planets are almost overhead. In other countries – for example those in Northern Europe the ecliptic can be so low in the sky the planets can only be glimpsed between buildings and trees.



The planets Mars and Mercury are hard to find in our evening sky just after sun set- although on February 12th the Moon will not be too far away. Look at the horizon below the Moon and in the darkening sky between you should if lucky just see two star-like objects. The higher of the two will be Mercury.

Wishing You Clear Skies

January News

I’m sure some of you have been thinking what happened to our January meeting at Pedro’s Castle and Nick’s monthly newsletter


Unfortunately 2013 brings changes to the Astronomical Society as Nick has taken a back seat in the Society for the time being due to Ill health

So apart from calling for volunteers’ and a current respite from collecting membership fees we will hopefully have our next meeting at Pedro’s Castle in mid February, I’ll try to avoid the 14!
Remember are meetings at Pedros are free of charge






Other Events
==========
We have been planing for sometime to offer to the General Public an Introductory course on Astronomy. This will be held at the UCCI Observatory and will cover both classroom and practical sessions. The course is non technical and open to all . The course will be taught by myself, Bill Hrudey and Richard McCloud and is an offical course  offrred by the UCCI. Because of this The cost of the course is CI $125 (plus an addition registration fee – either $10 or $25)


The course is for 7 weeks and will be held on Tuesday Evenings at 7:30 PM, starting 29th Jan
Registration for the course should be made by Friday 18th at the Admin Office on campus. However as this is a bit short notice and how to register at the college is somewhat of a grey area if you are unfamiliar with the procedure we have organized a free evening to sign up .
This will be held at the UCCI Observatory on Tuesday 22nd at 7:30 PM.

If enough people have registered then the course will commence the following Wednesday 27th January at 7:30 PM

For those wishing to register directly with the UCCI Admin Office by Friday – it is best located by asking the security guard on entering the campus.



Best Wishes to All in 2013 , and Clear Skies

 

Pedro Castle, December 16, 2012, 6.30

              In last months newsletter I noted that the bright star Alpheratz, shown above, is shared between the constellations Pegasus and Andromeda.
         Andromeda is famous for containing the Andromeda galaxy, shown as the red oval marked M31 above, within its boundaries.
    This spiral galaxy is the nearest to our Milky Way galaxy, but not the closest galaxy overall. At an apparent magnitude of 3.4, the Andromeda Galaxy is notable for being one of the brightest Messier objects, making it visible to the naked eye on moonless nights even when viewed from areas with moderate light pollution, approximately 2.5 million light-years (2.4×1019 km) from Earth
       The Andromeda Galaxy is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, the Andromeda Galaxy may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and could be the most massive in the grouping. The 2006 observations by the Spitzer Space Telescope revealed that M31 contains one trillion (1012) stars: at least twice the number of stars in the Milky Way galaxy, which is estimated to be 200–400 billion.
      The Andromeda Galaxy is approaching the Milky Way at about 100 to 140 kilometres per second (62 to 87 mi/s) which is about 1.96 billion to 2.74 billion miles per year, making it one of the few blueshifted galaxies. The Andromeda Galaxy and the Milky Way are thus expected to collide in about 4.5 billion years, although the details are uncertain since Andromeda's tangential velocity with respect to the Milky Way is known to only within about a factor of two.
      Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda's transverse velocity. Based on current calculations they predict a 50% chance that in a merged galaxy the solar system will be swept out three times farther from the galactic core than it is currently located. They also predict a 12% chance that the Solar System will be ejected from the new galaxy some time during the collision. Such an event would have no adverse effect on the system and chances of any sort of disturbance to the Sun or planets themselves may be remote.
       Without intervention, by the time that the two galaxies collide, the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life, which is currently estimated to occur in about 1.4 billion years due to gradually increasing luminosity of the Sun.
        Jupiter is bright in the eastern sky at viewing time, close to the bright star Aldebaran, Alpha Tauri, in the ascending constellation of Taurus.

Pedro Castle, November 16, 2012

      High in the sky as darkness falls is the constellation Pegasus. 
      Four stars of nearly equal brightness make up the asterism known as the “Great Square of Pegasus”, Scheat, Alpheratz, Markab and Algenib.
      The "Great Square" forms the body of the Winged Horse. To connect the rest of Pegasus, you'll need to use the right side of the "square." Pegasus is flying upside down across the sky. From Markab (lower right corner) extends the head of the Winged Horse.  
   The two front legs of Pegasus can be found off the star Scheat (upper right corner).  
   The star Alpheratz is shared by two constellations, Pegasus and Andromeda. The star is actually considered to be a star of Andromeda.

The Babylonian constellation IKU  had four stars of which three were later part of the Greek constellation Hippos (Pegasus). Pegasus, in Greek mythology, was a winged horse with magical powers. One myth regarding his powers says that his hooves dug out a spring, Hippocrene, which blessed those who drank its water with the ability to write poetry. Pegasus was the one who delivered Medusa's head to Polydectes, after which he travelled to Mount Olympus in order to be the bearer of thunder and lightning for Zeus. Eventually, he became the horse to Bellerophon, who was asked to kill the Chimera and succeeded with the help of Athena and Pegasus. Despite this success, after thedeath of his children, Bellerophon asked Pegasus to take him to Mount Olympus. Though Pegasusagreed, he plummeted back to Earth after Zeus either threw a thunderbolt to buck him off.
     In ancient Persia, Pegasus was depicted by al-Sufi as a complete horse facing east, unlike most other uranographers, who had depicted Pegasus as half of a horse, rising out of the ocean.
    In Hindu astronomy, the Great Square of Pegasus contained the 26th and 27th lunar mansions. More specifically, it represented a bedstead that was a resting place for the Moon.
   Warrau and Arawak peoples in Guyana used the stars in the Great Square to represent a grill on stilts.
     51 Pegasi, a star in this constellation, is the first Sun-like star known to have an extrasolar planet. IK Pegasi is the nearest supernova candidate.
    Messier 15 or M15 (shown on the illustration above) is a globular cluster in the constellation Pegasus. It was discovered by Jean-Dominique Maraldi in 1746 and included in Charles Messier's catalogue of comet-like objects in 1764. At an estimated 12.0 billion years old, it is one of the oldest known globular clusters.
      M15 is about 33,600 light-years from Earth, and 175 light years in diameter. It has an absolute magnitude of -9.2, which translates to a total luminosity of 360,000 times that of the Sun. Messier 15 is one of the most densely packed globulars known in the Milky Way galaxy. Its core has undergone a contraction known as 'core collapse' and it has a central density cusp with an enormous number of stars surrounding what may be a central black hole.                                                                                                                        
      Home to over 100,000 stars, the cluster is notable for containing a large number of variable stars (112) and pulsars (8), including one double neutron star system, M15 C. M15 also contains Pease 1, the first planetary nebula discovered within a globular cluster in 1928. Just three others have been found in globular clusters since then.
     Pegasus is also noted for its more unusual galaxies and exotic objects. Einstein's Cross is a quasar that has been lensed by a foreground galaxy. The elliptical galaxy is 400 million light-years away with a redshift of 0.0394, but the quasar is 8 billion light-years away. The lensed quasar resembles a cross because the gravitational force of the foreground galaxy on its light creates four images of the quasar.
      A quasi-stellar radio source ("quasar") is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies. While the nature of these objects was controversial until as recently as the early 1980s, there is now a scientific consensus that a quasar is a compact region in the center of a massive galaxy surrounding its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole. The quasar is powered by an accretion disc around the black hole.
        Stephan's Quintet is another unique object located in Pegasus. It is a cluster of five galaxies at a distance of 300 million light-years and a redshift of 0.0215. First discovered by Édouard Stephan, a Frenchman, in 1877, the Quintet is unique for its interacting galaxies. Two of the galaxies in the middle of the group have clearly begun to collide, sparking massive bursts of star formation and drawing off long "tails" of stars. Astronomers have predicted that all five galaxies may eventually merge into one large elliptical galaxy.

                   ASTRONOMICAL SOCIETY: OCTOBER 2012
                
       Weather permitting; we will meet on Thursday, 18th October, 6.30 p.m. at Pedro Castle.
If the sky is more than 50% cloud covered, we cancel. This can be, as you will appreciate, a sometimes difficult decision.
    Almost directly overhead at viewing time is the constellation Aquila.  Aquila lies just a few degrees north of the celestial equator and is located along the Milky Way. Because of this location along the line of our galaxy, many clusters and nebulae are found within its borders, but they are dim and there are few galaxies.
    Astronomers observed two major novae in Aquila, the first one being in 389 BC. It was recorded as brighter than the planet Venus. The second one was observed in the year 1918 (Nova Aquilae). It was brighter than Altair. A nova should not be confused with a supernova. A nova is an old star that brightens temporarily, and a supernova (dying star) is a massive star exploding.                                                      NASA’s Pioneer 11 mission will pass near one of constellation Aquila’s stars in about four million years.                                                                                                                                                  Altair (Alpha Aquila), the brightest star of the constellation, is a multiple star system. It is about eight times brighter than the sun and the twelfth brightest star in the night sky. It is an A-type main sequence star with an apparent visual magnitude of 0.77. Class A stars are among the more common naked eye stars, and are white or bluish-white. Other examples include Sirius, Deneb, Vega and Fomalhaut.  Altair is located 16.7 light-years (5.13 parsecs) from Earth and is one of the closest stars visible to the naked eye. Altair is a type-A main sequence star with approximately 1.8 times the mass of the Sun and 11 times its luminosity. Altair possesses an extremely rapid rate of rotation; it has a rotational period of approximately 9 hours. For comparison, the equator of the Sun requires just over 25 days for a complete

                  CAYMAN ISLANDS ASTRONOMICAL SOCIETY
                         NEWSLETTER; OCTOBER 2012
       Weather permitting; we will meet on Thursday, 18th October, 6.30 p.m. at Pedro Castle.
If the sky is more than 50% cloud covered, we cancel. This can be, as you will appreciate, a sometimes difficult decision.
    Almost directly overhead at viewing time is the constellation Aquila.  Aquila lies just a few degrees north of the celestial equator and is located along the Milky Way. Because of this location along the line of our galaxy, many clusters and nebulae are found within its borders, but they are dim and there are few galaxies.
    Astronomers observed two major novae in Aquila, the first one being in 389 BC. It was recorded as brighter than the planet Venus. The second one was observed in the year 1918 (Nova Aquilae). It was brighter than Altair. A nova should not be confused with a supernova. A nova is an old star that brightens temporarily, and a supernova (dying star) is a massive star exploding.                                                     
    NASA’s Pioneer 11 mission will pass near one of constellation Aquila’s stars in about four  million years.
                                                                                                                                                   Altair (Alpha Aquila), the brightest star of the constellation, is a multiple star system. It is about eight times brighter than the sun and the twelfth brightest star in the night sky. It is an A-type main sequence star with an apparent visual magnitude of 0.77. Class A stars are among the more common naked eye stars, and are white or bluish-white. Other examples include Sirius, Deneb, Vega and Fomalhaut.  Altair is located 16.7 light-years (5.13 parsecs) from Earth and is one of the closest stars visible to the naked eye. Altair is a type-A main sequence star with approximately 1.8 times the mass of the Sun and 11 times its luminosity. Altair possesses an extremely rapid rate of rotation; it has a rotational period of approximately 9 hours. For comparison, the equator of the Sun requires just over 25 days for a complete

The name Altair comes from the Arabic al-nasr al-ta’ir, meaning ‘flying eagle’ or ‘vulture’. Ptolemy called this star Aetus, the eagle, the same as the constellation. The German scholar Paul Kunitzsch notes that the Babylonians and Sumerians referred to Altair as the eagle star, testimony to an even more ancient origin of the name. Altair’s neighbouring stars Beta and Gamma Aquilae lie in the eagle’s neck and in its left shoulder respectively, according to Ptolemy’s description. These two stars have their own names, Alshain and Tarazed, which come from a Persian translation of an old Arabic word meaning ‘the balance’.
           In China, Altair and its two flanking stars, Beta and Gamma Aquilae, were known as Hegu, a large battle drum – beating the drum was a signal for the army to attack. The line to the south formed by Theta, 62, 58 and Eta Aquilae was Tianfu, the drumstick. Delta Aquilae and surrounding stars including Mu, Sigma and Iota were Youqi, a banner flying on the right side of the drum, while the stars of Sagitta to the north were a banner on the left of the drum.
    Altair and its attendant stars also had two other identifications. In one they were known as the Three Generals, the commanding officer in the centre flanked by two subordinates.

Aquila represents an eagle, the thunderbird of the Greeks. There are several explanations for the presence of this eagle in the sky. In Greek and Roman mythology, the eagle was the bird of Zeus, carrying (and retrieving) the thunderbolts which the wrathful god hurled at his enemies. But the eagle was involved in love as well as war.
   According to one story, Aquila is the eagle that snatched up the beautiful Trojan boy Ganymede, son of King Tros, to become the cup-bearer of the gods on Olympus. Authorities such as the Roman poet Ovid say that Zeus turned himself into an eagle, whereas others say that the eagle was simply sent by Zeus. Ganymede himself is represented by the neighbouring constellation of Aquarius, and star charts show Aquila swooping down towards Aquarius. Germanicus Caesar says that the eagle is guarding the arrow of Eros (neighbouring Sagitta) which made Zeus love-struck.