Pedro Castle, Tuesday, June 15th. 7.30 p.m. 2010

The constellation Corona Borealis is found nearly midway between Arcturus and Vega; a little closer to the first of these stars. It is characterized by a half-moon shaped line of stars, among which Gemma is conspicuous, similar to a precious stone on the crown (this star is also known with the name of Alphecca), which is a 2.2 magnitude star 75 light years away.

Although faint, the constellation is quite easy to make out.

The loop of nine stars from Pi to Rho Coronae Borealis was known in China as Guansuo, the prison for working-class miscreants; the prison for the upper classes was more auspiciously placed farther north, in Ursa Major.

Corona Borealis was sometimes considered to represent a crown that was given by Dionysus to Ariadne, the daughter of Minos of Crete. At other points it was considered to belong, in a sense, to Boötes, the herdsman. The Cheyenne nation of Native Americans called it the "Camp Circle" as they arranged their camps in a semicircle. In Welsh mythology, the Northern Crown was called Caer Arianrhod, ‘the Castle of the Silver Circle,’ and was the heavenly abode of the Lady Arianrhod.

Venus, Mars and Saturn are still bright in the sky.

Pedro Castle, Sunday, 16th May 2010, 7.30 p.m.

The sky is brilliant in the early evenings this month with three planets and bright stars along the line of the ecliptic.
The ecliptic is the apparent path that the Sun traces out in the sky during the year, appearing to move eastwards on an imaginary spherical surface, the celestial sphere, relative to the (almost) fixed stars.
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the celestial equator and the celestial poles.
Most planets go in orbits around the sun, which are almost in the same plane as the Earth's orbital plane, differing by a few degrees at most. As such they always appear close to the ecliptic when seen in the sky.
The name ecliptic arises because eclipses occur when the full or new Moon is very close to this path of the Sun.

On the 16th, Venus will be close to the crescent Moon in the west. Moving eastwards along the ecliptic, the Twins of Gemini, Castor and Pollux, come before Mars.
Saturn is roughly halfway between Regulus, in the constellation Leo, and Spica, α Virginis.
The distinctive constellation of Ursa Major is high in the north, and Crux, the Southern Cross is in the south.

Pedro Castle,April 18th, 7.00 p.m. 2010

Canis Minor, as shown above on the sky chart, is a small constellation which was included in the 2nd century astronomer Ptolemy's 48 constellations, and is still included among the 88 modern constellations. Its name is Latin for "smaller dog" in contrast to Canis Major, the larger dog, and it is commonly represented as one of the dogs following the constellation of Orion the hunter

Canis Minor contains only two bright stars, Procyon, which means "before the dog" in Greek, as it rises an hour before the 'Dog Star', Sirius, of Canis Major, and Gomeisa.

Procyon is the brighter of the two. To the naked eye, it appears to be a single star, the eighth brightest in the night sky with a visual apparent magnitude of 0.34. It is actually a binary star system, consisting of a white main sequence star, named Procyon A, and a faint white dwarf companion of spectral type DA, named Procyon B. The reason for its brightness is not its intrinsic luminosity but its closeness to the Sun; at a distance of 3.5 pc or 11.41 light years, Procyon is one of our near neighbours.

Procyon forms one of the three vertices of the Winter Triangle, along with Sirius and Betelgeuse.

Procyon A is a white star of spectral type F5; it is 1.4 times the mass, twice the diameter, and 7.5 times more luminous than the Sun. It is bright for its spectral class, suggesting that it is a subgiant that has completely fused its core hydrogen into helium, and begun to expand as "burning" moves outside the core. As it continues to expand, the star will eventually swell to about 80 to 150 times its current diameter and become a red or orange color. This will probably happen within 10 to 100 million years. It is expected that the Sun will also go through this process when hydrogen fusion ceases at its core.

The chart also shows the four planets visible. Mercury might be a little hard to see on Sunday, but it has been visible for the last two weeks.

This is a list of the 20 brightest stars as seen from the Earth (not including the Sun). The stars are numbered from 1 to 20 in sequence.

	Common Name	Constellation	Apparent Magnitude	Spectral Type	Luminosity (Sun = 1)	Distance (Light Years)	Radial Velocity (km / sec)
1	Sirius	Canis Major	-1.46	A1	26	8.7	-8
2	Canopus	Carina	-0.72	F0	15,000	310	+21
3	Alpha Centauri	Centaurus	-0.04	G2	1.7	4.3	-22
4	Arcturus	Boötis	0.00	K2	115	36	-5
5	Vega	Lyra	0.03	A0	52	25	-14
6	Capella	Auriga	0.08	G8 F0	90 70	43	+30
7	Rigel	Orion	0.12	B8	60,000	910	+21
8	Procyon	Canis Minor	0.38	F5	7	11.4	-3
9	Achernar	Eridanus	0.46	B5	400	85	+19
10	Betelgeux	Orion	0.0 - 0.9	M2	105,000 v	640	+21
11	Agena	Centaurus	0.61	B1	10,000	460	-11
12	Altair	Aquila	0.77	A7	10	16.6	-26
13	Acrux	Crux Australis	0.83	B1	3,200	360	-11
14	Aldebaran	Taurus	0.85	K5	120	68	+54
15	Antares	Scorpius	0.96	M1	7,500	330	-3
16	Spica	Virgo	0.98	B1	2,100	260	+1
17	Pollux	Gemini	1.14	K0	60	36	+3
18	Fomalhaut	Piscis Australis	1.16	A3	13	22	+7
19	Deneb	Cygnus	1.25	A2	70,000	1,800	-5
20	Becrux	Crux Australis	1.25	B0	8,200	425	+20

Pedro Castle, Thursday, 18th March 2010, 7.00 p.m.

Almost overhead as darkness falls, bright Mars shines close to the heads of the twins illustrated above, the constellation Gemini.
The two brightest stars in the constellation, marking the heads of the twins, are named Castor and Pollux. Astronomers have found that Castor is actually a complex system of six stars linked by gravity, although to the eye they appear as one. Pollux is an orange giant star. Unlike the twins that they represent, the stars Castor and Pollux are not related since they lie at different distances from us. Eta Geminorum is called Propus, meaning ‘forward foot’ in Greek, a name that first appears with Eratosthenes.
Gemini represents the twins Castor and Polydeuces (Pollux is the Latin form of his name); they were known to the Greeks as the Dioscuri, literally meaning ‘sons of Zeus’. However, mythologists disputed whether both really were sons of Zeus, because of the unusual circumstances of their birth. Their mother was Leda, Queen of Sparta, whom Zeus visited one day in the form of a swan (now represented by the constellation Cygnus). That same night she also slept with her husband, King Tyndareus. Both unions were fruitful, for Leda subsequently gave birth to four children. In the most commonly accepted version, Polydeuces and Helen (later to become famous as Helen of Troy) were children of Zeus, and hence immortal, while Castor and Clytemnestra were fathered by Tyndareus, and hence were mortal.
Castor and Polydeuces grew up the closest of friends, never quarrelling or acting without consulting each other. They were said to look alike and even to dress alike, as identical twins often do. Castor was a famed horseman and warrior who taught Heracles to fence, while Polydeuces was a champion boxer.

Near the three ‘foot’ stars lies M35, an open cluster. It was discovered by Philippe Loys de Chéseaux in 1745 and independently discovered by John Bevis before 1750. The cluster is scattered over an area of the sky almost the size of the full moon and is located 850 parsecs (2,800 light-years) from Earth.
It consists of several hundred stars scattered over an area the size of that covered by the full Moon. Even the naked eye finds this cluster easily under fairly good observing conditions. The slightest optical instrument will resolve the brighter stars and make it a splendid view at low magnifications, a nearly circular cluster with rather uniform stellar distribution. In telescopes, low powers and wide-field eye pieces show M35 at its best.
Of the other planets, Venus is visible in the west in the dusk, and Saturn is rising in the east.

Pedro Castle,Tuesday, 16th February, 7.00. p.m.

The prominent Winter constellations are now high overhead in the early evening, one of best known of which is Orion, the Hunter.
Orion includes the prominent asterism known as the Belt of Orion: three bright stars in a row. Surrounding the belt at roughly similar distances are four bright stars, which are considered to represent the outline of the hunter's body. Apparently descending from the 'belt' is a smaller line of three stars (the middle of which is in fact not a star but the Orion Nebula), known as the hunter's 'sword'.
The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light years across. Older texts frequently referred to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula.
The Nebula is in fact part of a much larger nebula that is known as the Orion Molecular Cloud Complex. The Orion Molecular Cloud Complex extends throughout the constellation of Orion and includes Barnard's Loop, the Horsehead Nebula, M43, M78 and the Flame Nebula. Stars are forming throughout the Orion Nebula, and due to this heat-intensive process the region is particularly prominent in the infrared.
The nebula is visible with the naked eye even from areas affected by some light pollution. It is seen as the middle "star" in the sword of Orion, which are the three stars located south of Orion's Belt. The star appears fuzzy to sharp-eyed observers, and the nebulosity is obvious through binoculars or a small telescope.
The Orion Nebula contains a very young open cluster, known as the Trapezium due to the asterism of its primary four stars. Two of these can be resolved into their component binary systems on nights with good seeing, giving a total of six stars. The stars of the Trapezium, along with many other stars, are still in their early years.

The Orion Nebula is an example of a stellar nursery where new stars are being born. Observations of the nebula have revealed approximately 700 stars in various stages of formation within the nebula.
Recent observations with the Hubble Space Telescope have yielded the major discovery of protoplanetary disks within the Orion Nebula, which have been dubbed proplyds, illustrated above. HST has revealed more than 150 of these within the nebula, and they are considered to be systems in the earliest stages of solar system formation. The sheer numbers of them have been used as evidence that the formation of star systems is fairly common in our universe.
Stars form when clumps of hydrogen and other gases in an H II region contract under their own gravity. As the gas collapses, the central clump grows stronger and the gas heats to extreme temperatures by converting gravitational potential energy to thermal energy. If the temperature gets high enough, nuclear fusion will ignite and form a protostar. The protostar is 'born' when it begins to emit enough radiative energy to balance out its gravity and halt gravitational collapse.
Typically, a cloud of material remains a substantial distance from the star before the fusion reaction ignites. This remnant cloud is the protostar's protoplanetary disk, where planets may form. Recent infrared observations show that dust grains in these protoplanetary disks are growing, beginning on the path towards forming planetesimals.
Once the protostar enters into its main sequence phase, it is classified as a star. Even though most planetary disks can form planets, observations show that intense stellar radiation should have destroyed any proplyds that formed near the Trapezium group, if the group is as old as the low mass stars in the cluster. Since proplyds are found very close to the Trapezium group, it can be argued that those stars are much younger than the rest of the cluster members.
Interstellar clouds like the Orion Nebula are found throughout galaxies such as the Milky Way. They begin as gravitationally bound blobs of cold, neutral hydrogen, intermixed with traces of other elements. The cloud can contain hundreds of thousands of solar masses and extend for hundreds of light years. The tiny force of gravity that could compel the cloud to collapse is counter-balanced by the very faint pressure of the gas in the cloud.
Whether due to collisions with a spiral arm, or through the shock wave emitted from supernovae, the atoms are precipitated into heavier molecules and the result is a molecular cloud. This presages the formation of stars within the cloud, usually thought to be within a period of 10-30 million years, as regions pass the Jeans mass and the destabilized volumes collapse into disks. The disk concentrates at the core to form a star, which may be surrounded by a protoplanetary disk. This is the current stage of evolution of the nebula, with additional stars still forming from the collapsing molecular cloud. The youngest and brightest stars we now see in the Orion Nebula are thought to be less than 300,000 years old, and the brightest may be only 10,000 years in age.
Some of these collapsing stars can be particularly massive, and can emit large quantities of ionizing ultraviolet radiation. An example of this is seen with the Trapezium cluster. Over time the ultraviolet light from the massive stars at the center of the nebula will push away the surrounding gas and dust in a process called photo evaporation. This process is responsible for creating the interior cavity of the nebula, allowing the stars at the core to be viewed from Earth. The largest of these stars have short life spans and will evolve to become supernovae.
Within about 100,000 years, most of the gas and dust will be ejected. The remains will form a young open cluster, a cluster of bright, young stars surrounded by wispy filaments from the former cloud. The Pleiades is a famous example of such a cluster.

Pedro Castle, Sunday, 17th January 2010, 6.30 p.m.

Every evening this month, Mars rises earlier until by the end of January it will be visible around sunset, staying up until dawn. The planet will come into Opposition on January 29, 2010 in the constellation Cancer. Two days before, on January 27, 2010, the planet will have come to its closest approach to Earth during this apparition: 99.33 million km (0.66399 AU). This is not very close, as Mars will be quite close to its aphelion at the time of this opposition; the aphelion is passed on March 31, 2010. This opposition will occur during Northern Spring and Southern Autumn on Mars, so primarily observable will be the Northern hemisphere of Mars.
This time, the usual opportunity to launch spacecraft to Mars will pass unused, for the first time since 1994: The two missions originally scheduled for this occasion have both been shifted to 2011/2012, Nasa's Mars Science Laboratory (MSL, also named Curiosity) as well as the Russian Space Agency's Phobos-Grunt spacecraft, a mission scheduled to return samples from Mars' moon Phobos.
Mars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. Unlike the Earth, Mars is now a geologically inactive planet with no known tectonic activity. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. The smooth Borealis basin in the northern hemisphere may be a giant impact feature covering 40% of the planet. Mars’ rotational period and seasonal cycles are likewise similar to those of Earth.
The exploration of Mars has been an important part of the space exploration programs of the Soviet Union, the United States, Europe, and Japan. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s. These missions were aimed at gathering data about current conditions and answering questions about the history of Mars as well as a preparation for a possible manned mission to Mars. The questions raised by the scientific community are expected to not only give a better appreciation of the red planet but also yield further insight into the past, and possible future, of Earth.
The exploration of Mars has come at a considerable financial cost with roughly two-thirds of all spacecraft destined for Mars failing before completing their missions, with some failing before they even begin. Such a high failure rate can be attributed to the complexity and large number of variables involved in an interplanetary journey, and has led researchers to jokingly speak of The Great Galactic Ghoul which subsists on a diet of Mars probes.
Mars is currently host to three functional orbiting spacecraft: Mars Odyssey, Mars Express, and the Mars Reconnaissance Orbiter. On the surface are the two Mars Exploration Rovers (Spirit and Opportunity, which took the photograph above) and several inert landers and rovers, both successful and unsuccessful. The Phoenix lander completed its mission on the surface in 2008. Observations by NASA's now-defunct Mars Global Surveyor show evidence that parts of the southern polar ice cap have been receding.