Sun is the source of light and radiant energy for all heavenly bodies of the Solar system.
The nine planets of the Solar System are named for Greek and Roman Gods and Goddesses.
The path along which each planet revolves round the Sun is called its ORBIT. 
Farthest planet from sun is Pluto (????) – distance about 5900 million km from the sun. (now it is considered as dwarf planet.)
- Without sun, there would be no solar system. The sun provides not only energy required for life, but also provides gravitational force to hold the planets in the orbit.
- The Sun is the most massive body in the Solar System, containing 98% of the mass of the Solar System. The Sun is more than 330,000 times more massive than the Earth. The Sun is also the Solar System's largest body, with a diameter of 1,391,900 kilometers, over 109 times that of Earth's.
- The Sun is layered, and can effectively be divided into three regions, the core, the radiative zone, and the convective zone. The "surface" of the Sun that we see is the photosphere, above which lies the chromosphere and the outlying corona.
THE SUN
The Sun is hot gaseous body. The Sun’s age is about 5 billion years. Its energy comes from nuclear fusion (where hydrogen is converted to helium) within its core. This energy is released from the Sun in the form of heat and light.
- Stars are the only solar bodies that generate their own light. Very bright planets, such as Venus and our moon, appear bright because they are reflecting sunlight.
- Remember: Stars produce light. Planets reflect light.
- Our sun is classified as a yellow main sequence star. A star’s temperature determines its “color.” The coldest stars are red. The hottest stars are blue.
- The sun is the biggest, brightest, and hottest object in the solar system. It has a radius of 5900 million km. The sun is an ordinary star. It is made of about 70% hydrogen and 28% helium. The surface temperature of Sun is 6000 degree C. The core of the sun has temperature of 2,00,00,000 degree C.
- It rotates on its axis every 27 days approximately.-Not uniform since it is a big ball of gas and not a solid.
- Sun exudes tremendous energy by a process similar to the explosion of a hydrogen bomb. Within the sun, this process is continuous.
- The Earth intercepts only a small faction of this energy- provides warmth, light and even rain required for life on earth.
SUN SPOTS 
Sunspots reside in the photosphere, and are large dark regions of strong local magnetism. The magnetic field of a sunspot prevents the escape of energy from below, and consequently sunspots have lower temperatures than the rest of the photosphere. However, sunspots only appear dark when viewed against the hotter, brighter surroundings. If you took
a sunspot off the Sun and placed it in the night sky, it would shine very brightly. Galileo first discovered the Sunspots and from them he deduced that Sun rotates on its axis.
Under Sun’s gravitational force each planet follows an elliptical orbit around the Sun.
All planets rotate in an anti-clockwise direction except Venus and Uranus.
Uranus and Venus rotate clockwise direction, i.e. east to west.
The8 Planets of the Solar System
Mercury, Venus,Earth, Mars, Jupiter, Saturn, Uranus and Neptune are 8 planets . Pluto is considered as dwarf planet.
INFERIOR AND SUPERIOR PLANETS:-
- Planets are classified on basis of their distances from the Sun.
- Mercury and Venus are called Inferior Planets, as their orbits lie within the orbit of the earth. Farther planets from Mars to Neptune, are called Superior Planets.
INNER AND OUTER PLANETS:-
Planets are also classified on the basis of their physical properties.
- Mercury, Venus, Earth & Mars – inner planets – small in size – made of rocky substances and have a high density – hotter than Outer planets – also called Terrestrial Planets.
DISTINGUISH BETWEEN INNER PLANETS AND OUTER PLANETS:-
INNER PLANETS onsist of Mercury, Venus, Earth, Mars and OUTER PLANETS consist of Jupiter, Saturn, Uranus, Neptune.Inner planets are closer to the Sun whereas outer planets are far away from the Sun.
Inner Planets have a solid surface made of dense metallic minerals. They are called rock-type planets. Outer Planets' surface is not solid but made up of hot gases, mainly hydrogen & helium. They are called gas-type planets.
Inner Plaets travel faster and have shorter period of revolution. Outer Planets travel more slowly and have a longer period of revolution.
Inner Planets are much smaller.Our earth which is the largest in size is a quarter of Neptune. Outer Planets are extremely large. Jupiter is the largest and others put together would not be equal to half its volume.
QUESTION 1: Name the Inferior and Superior Planets.
ANSWER :Mercury and Venus – Inferior
Mars to Pluto – SUPERIOR
ANSWER Jupiter, Saturn, Uranus, Neptune.
Mercury sweeps through its orbit at nearly 50km per second, faster than any other planet. It has a revolution period of 88 days. A revolution period is time it takes for a planet to complete one full orbit around the sun. This is also called a year. It has extreme temperature fluctuations, ranging from 800°F (daytime) to -270°F (nighttime). Even though it is the closest planet to the sun, recent radar info suggests there is ICE on Mercury! Scientists believe the ice is protected from the sun’s heat by crater shadows. It is covered with meteorite impacts and barely has a trace of an atmosphere.
.The surface of Mercury rough and pockmarked with craters.
VENUS
Named after goddess of love & beauty
•Known as morning star when high in eastern sky
•Evening star when visible in the western night sky
Venus is the brightest object in the sky after the sun and moon because its atmosphere reflects sunlight so well. People often mistake it for a star.
The atmosphere of Venus has a large amount of carbon dioxide gas. Carbon dioxide traps heat in Venus’s atmosphere, causing the surface temperatures to increase greatly. We call this effect the Greenhouse Effect. Venus’s Greenhouse Effect is so strong that its temperature about 470 degree C .
Venus has no moons. It has thick yellowish clouds composed of sulfuric acid driven by fast winds. Its surface is dry and dusty with craters, mountains, and volcanoes.
Venus is the sixth largest planet. It’s about three-fourths the size of earth.
The surface is rocky and very hot. The atmosphere completely hides the surface and traps the heat.
Located at a mean distance of 108 million km from the Sun.
It takes longest period -243 days to complete one rotation.
It rotates from east to west.
It completes one revolution around the Sun in a shorter period of only 223 days . So a day on Venus is longer than its year.
Unlike earth, it is covered with a very thick blanket of clouds which reflects 75% of the light reaching.
The clouds have never parted enough to allowa view of the surface through the telescope and so Venus presents an unchanging view-a white planet with no visible markings on it.
It is called as ‘Veiled Planet’.
JUPITER
Jupiter is the largest and most massive planet: it’s diameter is 11 times bigger than that of the Earth’s. Overall, Jupiter is about 318 times the size of Earth. Jupiter is composed almost entirely of hydrogen and helium.Because Jupiter rotates so quickly, it’s clouds form belts (low-lying, relatively warm cloud layers) and zones (bright, high-altitude, cooler cloud layers) that encircle the planet.
Jupiter’s characteristic Great Red Spot is an enormous storm, consisting of a spiraling column of clouds big enough to contain three Earths. The clouds are colder than the surrounding areas, and so the Great Red Spot sits about five miles above the upper cloud layer.
JUPITER'S RED SPOT:
The Great Red Spot, a huge storm of swirling gas that has lasted for hundreds of years.
Jupiter does not have a solid surface. The planet is a ball of liquid surrounded by gas.
Voyager 1 took this photo of the planet Jupiter on January 24, 1979 while still more than 40 million km away.
MOONS OF JUPITER
Jupiter has four large Galilean moons, twelve smaller named moons and twenty-three more recently discovered but not named moons.
We’ll take a look at the four large Galilean moons which were first observed by Galileo in 1610.
Saturn is the second largest planet and the sixth from the sun.
It is made of materials that are lighter than water. If you could fit Saturn in a lake, it would float!
It, like Jupiter, is composed almost entirely of hydrogen and helium. Saturn is the least dense of all the planets. In fact, Saturn’s density is less than that of water.
It has many rings composed primarily of ice with some ice-coated rocky particles. Saturn’s rings are very wide (they extend outward to about 260,000 miles from the surface) but very thin (less than 1 mile thick).
It has 18 known moons, some of which orbit inside the rings!
It's rings are not solid; they are composed of small countless particles.
The rings are very thin. Though they’re 250,000km or more in diameter, they’re less than one kilometer thick.
1,25,000 rings in saturn. Ring consists of Dust and gaseous particles.there are gaps between the rings. Has 32 natural satellites. Believed that there may be life in Titon, satellite of Saturn.
URANUS
It has 11 dark rings surrounding it. These rings contain some of the darkest matter in our solar system.
It has 15 known moons, and scientists suspect more lurk within its rings.
It is the third largest planet and the seventh from the sun.
It is one of the giant gas planets. Uranus is blue-green because of the methane in its atmosphere
NEPTUNE
Neptune has the fastest winds on the solar system: up to 2000 km/hr.
It is also blue in color due to methane gas in its atmosphere.
It has a Great Dark Spot in its atmosphere. The Great Dark Spot is a huge storm the size of Earth.
Neptune is the fourth largest planet and the eight from the sun.
Because of the orbits, from 1979 to 1999, Neptune was the ninth planet.Like Uranus, the methane gives Neptune its color.
PLUTO
Based on current data, scientists believe it is a small, rocky planet.It seems to lie on its side: its equator points straight up, and one of its poles points directly at the sun.It was located and named in 1930.
Pluto: The First Dwarf Planet-It is actually smaller than one of Neptune's moons, Triton is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun.
For many years, Pluto was thought of as the farthest known planet from the Sun.
It has a very unusual orbit. Once every 248 Earth years, Pluto swings inside the orbit of Neptune. It stays there for twenty years.
During those twenty years, Pluto is closer to the Sun than Neptune.
While it is closer to the Sun, Pluto has an atmosphere. The methane and nitrogen frozen at the poles thaw out, rise, and temporarily form an atmosphere.
As it moves toward its farthest point from the Sun, Pluto's atmosphere freezes and falls back on the surface of the planet.
Since the year 2000, astronomers realized that Pluto was not like the other eight planets but very much like a new group of objects found in the outer solar system. In 2006, astronomers re-classified Pluto to be a dwarf planet .
Pluto has three moons. It's largest moon, Charon, is half the size of Pluto.
In 2005, astronomers observed two more moons of Pluto. The moons were named Nix and Hydra.
Name Pluto was suggested by an 11 year old schoolgirl – Venetia BurneyGave name because the name of Roman God of the underworld was suitable for the planet so far from the Sun
Facts about Pluto
Average Solar Distance : 6 billion km
Revolution Period: 248 Earth years
Rotation Period: 6.4 Earth days
Equatorial diameter: 2400 km Earth
No comments:
Post a Comment