Monday, November 12, 2012


An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer. An eclipse is a type of syzygy.
The term eclipse is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth-Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon.


A solar eclipse occurs when the Moon passes in front of the Sun and obscures it totally or partially. This configuration can only exist at New Moon, when Sun, Moon and Earth are on a single line with the Moon in the middle.

There are four types of solar eclipses:
  • total eclipse occurs when the dark silhouette of the Moon completely obscures the intensely bright light of the Sun, allowing the much fainter solar corona to be visible. During any one eclipse, totality occurs at best only in a narrow track on the surface of Earth.
  • An annular (ring-formed) eclipse occurs when the Moon's center passes in front of Sun's center while the Moon is near apogee. The Moon's angular diameter is then smaller than that of the Sun so that a ring of the Sun can still be seen around the Moon. This is similar to a penumbral eclipse.
  • hybrid eclipse (also called annular/total eclipse) shifts between a total and annular eclipse. At certain points on the surface of Earth it appears as a total eclipse, whereas at other points it appears as annular. Hybrid eclipses are comparatively rare.
  • partial eclipse occurs when the Sun is only partially overlapped by the Moon.



Lunar eclipses occur when the Moon passes through the Earth's shadow. Since this occurs only when the Moon is on the far side of the Earth from the Sun, lunar eclipses only occur when there is a full moon. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse also lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour. There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's umbra; and total, when the Moon crosses entirely into the Earth's umbra.







Wednesday, November 7, 2012



The EarthDuring the day earth receives light from The Sun directly and at night the light of the sun is directed towards The Earth through The Moon.  Earth interacts with other objects in space, especially the Sun and the Moon. During one orbit around the sun, the Earth rotates about its own axis 366.26 times, creating 365.26 solar days, or one sidereal year. The Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days).


The MoonWe see the Moon because of sunlight that is reflected by it.  It is the brightest object in the sky after the Sun, although its surface is actually very dark. The Moon's current orbital distance, about thirty times the diameter of the Earth, causes it to appear almost the same size in the sky as the Sun.


The Sun.   It  has “burned” for more than 4.5 billion years. It warms our planet every day and provides the light by which we see all the beautiful things around us. Sunlight is necessary for life on Earth.  The Sun is currently traveling through the Local Interstellar Cloud in the Local Bubble zone, within the inner rim of the Orion Arm of the Milky Way galaxy. The Sun orbits the center of the Milky Way at a distance of approximately 24000-26000 light-years from the galactic center, completing one clockwise orbit, as viewed from the galactic north pole, in about 225–250 million years.




  • The New moon is when the moon is all dark. None of the moon that we can see is lit up during the new moon.
  • Crescent moon is when the moon is between the new and quarter moon stages. It looks like a "C" shape.
  • The Quarter moon is when half of the moon is visible. If the moon is waxing, it is called the first quarter, if the moon is waning, it is the last quarter
  • Gibbous moon is between the quarter and full moon stages. More than half of the moon can be seen, but not all of it.
  • The Full moon is when the moon is all lit up. All of the moon that we can see is lit up by the Sun during the full moon.
  • A second full moon in one calendar month is usually called a blue moon. The saying "Once in a blue moon" refers to something that does not happen often - like a blue moon.





Constellations are named patterns of stars. All societies created them. The classical -- "ancient" -- constellations that populate our sky began in the lands of the middle east thousands of years ago, their origins largely lost to time. They passed through the hands of the ancient Greeks, who overlaid them with their legends and codified them in story and verse. During Roman times they were assigned Latin names. 

The 48 ancient constellations single out only the bright patterns. From around 1600 to 1800, post-Copernican astronomers invented hosts of "modern" constellations from the faint stars that lie between the classical figures, from pieces of ancient constellations, and from the stars that occupy the part of the southern sky that could not be seen from classical lands. Later astronomers broke the ship Argo into three parts, yielding 50 ancient constellations. 


Crux is the smallest of the 88 modern constellations, but is one of the most distinctive. Its name is Latin for cross, and it is dominated by a cross-shaped asterism that is commonly known as the Southern Cross. Southern cross can be seen as a brilliant cross in the southern sky and it show the South Pole.


The Big Dipper, also known as the Plough or the Saptarishi (after the seven rishis), is an asterism of seven stars that has been recognized as a distinct grouping in many cultures from time immemorial. Big Dipper is a group of seven bright stars that forms a pattern of a handle and a bowl. The component stars are the seven brightest of the formal constellation Ursa Major


Scorpion, sometimes known as Scorpio and Scorpius, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is (Unicode). It lies between Libra to the west and Sagittarius to the east. It is a large constellation located in the southern hemisphere. Scorpion can be seen clearly with its head, long body, tail and stinger between June and August.


Orion sometimes subtitled The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognizable constellations in the night sky.Its name refers to Orion, a hunter in Greek mythology. Orion can be seen clearly as a hunter with a belt and sword between December and February. You can see Orion the best in the winter.


Tuesday, November 6, 2012


What is the Solar System? Solar system is Sun and everything that travels around it. The Solar System is elliptical in shape. That means it is shaped like an egg. The Sun is in the center of the Solar System and always in motion. The Solar System consists of the Sun and its planetary system of eight planets, their moons, and other non-stellar objects. It formed approximately 4.6 billion years ago from the collapse of a giant molecular cloud.


The smaller inner planets, MercuryVenusEarth and Mars, also called the terrestrial planets, are primarily composed of rock and metal. The four outer planets, called the gas giant, are substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are composed mainly of hydrogen and helium; the two outermost planets, UranusNeptune and Pluto are composed largely of ices, such as water, ammonia and methane, and are often reffered to separately as "ice giants".


Mercury (0.4 AU from the Sun) is the closest planet to the Sun and the smallest planet in the Solar System (0.055 Earth masses). Mercury has no natural satellites, and its only known geological features besides impacts craters are lobed ridge or rupes, probably produced by a period of contraction early in its history. Mercury is too close to the Sun and its temperature is too hot to support life.


Venus (0.7 AU from the Sun) is close in size to Earth (0.815 Earth masses), and has a thick silicate mantle around an iron core, a substantial atmosphere and evidence of internal geological activity. However, it is much drier than Earth. Venus has no natural satellites, and is the hottest planet with over 400°C because a great amount of heat from the Sun is trapped in its atmosphere.


Earth (1 AU from the Sun) is the largest and densest of the inner planets, known as an ocean planet, is the only one known to have current geological activity and is the only place in the Solar System where life is known to exist. Earth's atmosphere is radically different from those of the other planets, have been altered by the presence of the life to contain 21% free oxygen.


Mars (1.5 AU from the Sun) is smaller than Earth and Venus (0.017 Earth masses). Mars is a cold desert world. It is half the diameter of Earth and has the Same amount of dry land, like Earth. Mars has seasons, polar ice caps, volcanoes, canyons and weather, but its atmosphere is too thin for liquid water to exist for long on the surface.


Jupiter (5.2 AU from the Sun), at 318 Earth masses,  is 2.5 times the mass of all the other planets put together. It is composed largely of hydrogen and helium. Jupiter has 67 known satellites. The four largest, Ganymede, Callisto, Io and Europa, show similarities to the terrestrial planets, such as volcanism and internal heating.


Saturn (9.5 AU from the Sun), distinguished by its extensive ring system, has several similarities to Jupiter, such as its atmospheric composition and magnetosphere. Although Saturn has 60% of Jupiter's volume, it is less than a third massive, at 95 Earth masses, making it the least dense planet in the Solar System. The rings of Saturn are made up of small ice and rock particles. Saturn has 62 confirmed satellites; two of which, Titan and Enceladus, show signs of geological activity, through they are largely made of ice.


Uranus (19.6 AU from the Sun), at 14 Earth masses, is the lightest of the outer planets. Uniquely among the planets, it orbits the Sun on its side; its axial tilt is over ninety degrees to the ecliptic. It has much colder core than the other gas giants, and radiates very little heat into space. Uranus has 27 known satellites, the largest ones being Titania, Oberon, Umbriel, Ariel, and Miranda.


Neptune ( 30AU from the Sun ), through slightly smaller than Uranus, is more massive (equivalent to 17 Earth masses) and therefore more dense. It radiates more internal heat, but not as much as Jupiter or Saturn. Neptune has 13 Known satellites. The largest, Triton, is geologically active, with Geysers of liquid nitrogen. Neptune is covered with blue ocean of the liquid methane.


Pluto (32.1 AU from the Sun ) is the second-most-massive known dwarf planet in the solar system (after Eris) and the tenth-massive body observed directly orbiting the Sun. Originally classified as the ninth planet from the Sun. Pluto is very cold because it is far from the Sun.