THE SPACE

CLASS : 4 UPM

TEACHER’S NAME : MRS.VICTORIA

SCHOOL : SJK(T) KAJANG

MOONIESHAH SRI RAVINDREN

CONTENTS

TOPIC PAGEThe Space 1The constituents of the space 2Planets in the Space 2Positions of the planets 3Sun and planet summery 4Natural satellite 5Asteroid 6Comets 7Meteors 8Mercury 9 – 10Venus 11 -13Earth 14-15Mars 16Jupiter 17 -19Saturn 20- 21Uranus 22- 23Neptune 24- 25Pluto 26 - 27Bibliography 28

5

The Space

1

SPACEOther ConstituentsAsteroids Meteoroids Comets MeteorsNatural SatellitesMove round the planetsPlanetsMercuryVenusEarthJupiterSaturnUranusNeptunePlutoThe Earth: Perfect placement in the Space to support life The SunProduces heat and lightA star: Centre of the Solar SystemMove round the Sun in their orbits

Moon: Earth’s natural satelite

THE CONSTITUENTS OF THE SPACE1. The Space consists of:

a) The Sunb) Planetsc) Natural Satellitesd) Asteroidse) Meteorsf) Comets

2. a) The Sun is the centre of the Space.

b) It is star because it gives out light and heat. It is the only star in the Space.

c) The Sun is the biggest body in the Space. It consists of a ball of hot gases.

PLANETS IN THE SPACE1) Planets are bodies in the Space that move round the Sun.

a) A planet does not give out its own light and heat. b) We can see other planets from Earth because they reflect light from the Sun.

2) There are nine planets in the Space:

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

3) Each planet moves in a large oval path called an orbit. It also rotates on its own axis.4) The time taken by the planets to make one complete movement round the Sun

depends on their distance from the Sun.

2

POSITIONS OF THE PLANETS

Planet Distance from the Sun(million km) Time taken to orbit the SunMercury 58 88 daysVenus 108 225 daysEarth 150 365 1/4 daysMars 230 687 daysJupiter 780 12 yearsSaturn 1 430 29.5 yearsUranus 2 870 84 yearsNeptune 4 500 165 yearsPluto 5 900 248 years

The table shows the relationship between the distance of planets from the Sun and the time taken by the planets to orbit the Sun.

3

Sun and Planet Summary

The following table lists statistical information for the Sun and planets:

Planet Distance(AU)

Radius(Earth's)

Mass(Earth's)

Rotation(Earth's)

Moons OrbitalInclinatio

n

OrbitalEccentricit

y

Obliquity Density(g/cm3)

Sun 0 109 332,800 25-36* 9 --- --- --- 1.410Mercury 0.39 0.38 0.05 58.8 0 7 0.2056 0.1° 5.43

Venus 0.72 0.95 0.89 244 0 3.394 0.0068 177.4° 5.25Earth 1.0 1.00 1.00 1.00 1 0.000 0.0167 23.45° 5.52Mars 1.5 0.53 0.11 1.029 2 1.850 0.0934 25.19° 3.95

Jupiter 5.2 11 318 0.411 16 1.308 0.0483 3.12° 1.33Saturn 9.5 9 95 0.428 18 2.488 0.0560 26.73° 0.69Uranus 19.2 4 17 0.748 15 0.774 0.0461 97.86° 1.29

Neptune 30.1 4 17 0.802 8 1.774 0.0097 29.56° 1.64Pluto 39.5 0.18 0.002 0.267 1 17.15 0.2482 119.6° 2.03

The Sun's period of rotation at the surface varies from approximately 25 days at the equator to 36 days at the poles. Deep down, below the convective zone, everything appears to rotate with a period of 27 days.

4

NATURAL SATELLITE The term moon (never capitalized) is used to mean any natural satellite of the

other planets. There are, at least, 100 moons within Earth's solar system, and presumably many others orbiting the planets of other stars. Typically the larger gas giants have extensive systems of moons. Mercuryand Venus have no moons at all, Earth has one large moon, Mars has two tiny moons, and Pluto a large companion called Charon (sometimes considered to be a double planet).

Most moons are assumed to have been formed out of the same collapsing region of protoplanetary disk that gave rise to its primary. However, there are many exceptions and variations to this standard model of moon formation that are known or theorized. Several moons are thought to be captured foreign objects, fragments of larger moons shattered by large impacts, or (in the case of Earth's moon) a portion of the planet itself blasted into orbit by a large impact. As most moons are known only through a few distant observations through probes or telescopes, most theories about them are still uncertain.

Most moons in the solar system are tidally locked to their primaries; an exception is Saturn's moon Hyperion, which rotates chaotically due to a variety of external influences. No moons have moons of their own; the tidal effects of their primaries make orbits around them unstable. However, several moons have companions in their Lagrangian points (eg, Saturn's moons Tethys and Dione).

The recent discovery of Ida's moon Dactyl confirms that some asteroids also have moons. The largest moons in the solar system (those bigger than about 3000 km across) are

Earth's Moon, Jupiter's Galilean moons Io, Europe, Ganymede, and Callisto, Saturn's moon Titan, and Neptune's captured moon Triton. For smaller moons see the appropriate planets.

5

ASTEROID An asteroid is a large rock in outer space. Some, like Ceres, can be very

large, while others are as small as a grain of sand. Due to their smaller size, asteroids do not have enough gravity to pull themselves into the shape of a ball.  Astronomers group asteroids into different categories based on the way they reflect sunlight.

The asteroid belt is divided into an inner belt and an outer belt. The inner belt which is made up of asteroids that are within 250 million miles of the Sun contains asteroids that are made of metals.

The outer belt, which includes asteroids 250 million miles beyond the Sun, consists of rocky asteroids. These asteroids appear darker than the asteroids of the inner belt, and are rich in carbon.

Asteroids are left over materials from the formation of the Solar System.  These materials were never incorporated into a planet because of their proximity to Jupiter's strong gravity.

26 very large asteroids have been discovered, which is probably most of the big ones. But there are still millions of smaller ones that we have yet to see because they are too tiny, only a mile or so across.

If we stuck all the asteroids together how big would the new planet be?If all the materials of all the asteroids were squashed up into one planet it would be smaller than our moon.

6

COMETS A comet is a small world which scientists sometimes call a planetesimal. They are made out

of dust, and ice. Kind of like a dirty snow ball.Comets come from two places:  The Kuiper Belt, and the Oort Cloud. 

Imagine a place far far away, at the very edge of the Solar System. A place where millions of comets can be seen swishing around in every direction. These Icy comets are orbiting the Sun in two different places, both of which are very distant.  One place is called the Oort cloud, and the other is called the Kuiper Belt. 

A comet will spend billions of years in the Kuiper Belt or Oort Cloud.  Sometimes two comets will come very close to each other, or even crash into one another.  When this happens the comets change directions.  Sometimes their new path will bring them into the Inner Solar System. 

This is when a comet begins to shine. Up until now the comet has been among millions of others exactly the same, but as they approach the warmer Inner Solar System they begin to melt leaving behind magnificent tails.

Unfortunately Comets don't live very long once they enter the warmer part of the Solar System. Just like a snowman melts in the summer, comets melt in the Inner Solar System.   Although it is the most glorious part of their lives, traveling through the Inner Solar System eventually kills them.  After several thousand years they melt down to a little bit of ice, and dust, not nearly enough to leave a tail. Some even melt away completely.

Unlike a recent blockbuster movie showing a space ship flying past giant rocks the size of houses, a comets tail is actually quite safe. The only thing that would hit your ship would be microscopic pieces of dust.

7

METEORS Meteors or meteorites are bits of rock (likegranite) and ice - usually a mixture of rock and

iron and nickel but sometimes just rock or justiron - from out in space that get sucked into the gravity of the Earth and fall through ouratmosphere to the ground.

Usually this is because a comet has passed close enough to the Earth for Earth's gravity to grab some of its material. A meteor is the same thing as a shooting star or a falling star - they're not really falling stars, but some people call them that.

Meteors look like stars as they fall because when they hit Earth's atmosphere the friction of the rock rubbing against the atmosphere causes heat and light, like a fire. This heat melts all the ice off the meteor.

Most meteors are tiny, the size of pebbles, and most of them fall into the ocean, because more of the Earth is ocean than there is land. Even if they fall on land, these tiny meteors don't do any harm. Sometimes, though, much larger meteors do fall to Earth. One really huge meteor, about eight miles across, smashed into the Earth about 65 million years ago, where it made a huge crater and sent thousands of tons of dust up into the air. As a result of this meteor, Earth got much cooler for a while, and most of the dinosaurs died

8

MERCURYMercury is the closest planet to the sun and hot, hot, hot. To get a feel for it, we need to look at facts on the Planet.

Mercury is unlike any other planet in the solar system. Its unique location, rotation and orbit around the sun make it behave differently than other planets. 

Mercury is the closest planet to the Sun. Mercury rotates the Sun in only 88 days. Mercury rotates very slowly on its axis with one day taking 58 Earth days. Mercury barely has any atmosphere, but does have glaciers. Mercury is named after the Roman messenger of the gods. On average, Mercury is 36 million miles from the Sun. During the day, the average temperature on Mercury is 800 degrees Fahrenheit. During the night, the average temperature is – 300 degrees. Mercury is 38 percent of the diameter of the Earth. Mercury has no moons. Small in diameter, Mercury is the second largest planet when measured by mass. Mercury is primarily comprised of iron, which accounts for its heavy mass. Mercury has the largest known impact crater of any planet, named Beethoven and 643 kilometers in

size. Mercury has an eccentric orbit around the Sun, meaning it is closer and farther from the Sun at

different points in time. At its closest orbit, Mercury is “only” 46 million kilometers from the sun.

9

During Mercury's distant past, its period of rotation may have been faster. Scientists speculate that its rotation could have been as rapid as 8 hours, but over millions of years it was slowly despun by solar tides. A model of this process shows that such a despinning would take 109 years and would have raised the interior temperature by 100 degrees Kelvin.

10

VENUS In astronomy mythology, Venus was the Roman goddess of love and beauty.

In Greek her name was Aphrodite.

Because Venus and the Earth are almost the exact same size, you would weigh almost exactly the same on either planet. If you weighed 70 pounds on Earth you would weigh 63 pounds on Venus. 

The Planet: The planet Venus has long been one of the most misunderstood of all the inner planets. Like the Earth, Venus has an atmosphere. However, this atmosphere is far thicker than that of the Earth, making it difficult for modern science to penetrate.

Because we cannot see the surface of the planet Venus visually, there is much we still do not know about how this planet looks, and what it is like. However, using special instruments and probes scientists have in recent years unlocked many of the secrets long hidden by this mysterious world.

The Earth Has A Sister Venus is in many ways Earth's sister planet. It is almost identical in size, and chemistry as the Earth. In other words Venus is made up of almost the exact same types of materials as the Earth, in about the same amounts.

However if they are twins, then Venus is the evil twin, she is the Earth gone wrong, very wrong. Venus is a deadly world, where the surface temperature is hot enough to cook a meal in mere minutes. There is no where to hide from this ever present furnace.

Global Warming

In the early days of Venus' 4 billion year long life, it would have appeared very

11

similar to the Earth. The two would have been almost identical. However over a period of a few million years forces on Venus caused it to take a very different course than the Earth.

Venus lies much closer to the Sun than does our planet. That single fact has caused an unstoppable chain of events that doomed Venus to its fiery existence. Owing to its closer proximity to the Sun, Venus' temperature should have been only slightly warmer than that of the Earth.

As the planet warmed, water which formed oceans, lakes, and rivers on the Earth, evaporated. This increase in water vapor began a cycle of global warming that could not be stopped. Water vapor is a very effective greenhouse gas. The increase in water vapor caused the temperature to rise further, which caused more water to evaporate, causing the temperature to climb still further.

Today it is likely that all of Venus' water has evaporated, into the atmosphere. This atmosphere effectively traps the Sun's energy causing the surface to burn much hotter than it naturally would.

Venus Is Dry The Earth has a protective layer known as the Ozone Layer. This important shield protects the Earth from the Sun's ultraviolet radiation. Venus does not have an ozone layer. As a result the ultraviolet radiation from the Sun finds its way directly into Venus' atmosphere. Over many billions of years this radiation has slowly broken down water molocules into hydrogen and oxygen. As a result there is today very little water left on Venus.

How Does Venus Cool? Like the planet Earth, Venus also has a liquid molten core. As the planet ages, this core slowly cools. On Earth this cooling takes the form of volcanic and tectonic activity. On the Earth, there are always hot spots somewhere, where heat can escape allowing the core to become more cool.

Venus does not cool itself in the same way. Instead many scientists believe that every so often much of the surface of Venus actually melts, letting of great amounts of heat as it cools. It is not clear why to similar planets would cool is such different ways, however it is believed that the oceans on Earth play a key role in helping promote volcanic and tectonic cooling.

12

Venus StatisticsMass (kg) 4.869e+24Mass (Earth = 1) .81476Equatorial radius (km) 6,051.8Equatorial radius (Earth = 1) .94886Mean density (gm/cm^3) 5.25Mean distance from the Sun (km) 108,200,000Mean distance from the Sun (Earth = 1) 0.7233Rotational period (days) -243.0187Orbital period (days) 224.701Mean orbital velocity (km/sec) 35.02Orbital eccentricity 0.0068Tilt of axis (degrees) 177.36Orbital inclination (degrees) 3.394Equatorial surface gravity (m/sec^2) 8.87Equatorial escape velocity (km/sec) 10.36Visual geometric albedo 0.65Magnitude (Vo) -4.4Mean surface temperature 482°CAtmospheric pressure (bars) 92Atmospheric compositionCarbon dioxideNitrogen

Trace amounts of: Sulfur dioxide, water vapor,carbon monoxide, argon, helium, neon,hydrogen chloride, and hydrogen fluoride.

96% 3+% 

13

EARTH In astronomy mythology, Her Greek name was Gaea. Earth was the

mother of the mountains, valleys, streams and all other land formations. She was married to Uranus.

How big is the Earth? The Earth is the biggest of all the terrestrial planets. A terrestrial planet is a dense planet found in the inner Solar System. 

The Planet: Our planet is an oasis of life in an otherwise desolate universe.  The Earth's temperature, weather, atmosphere and many other factors are just right to keep us alive. 

14

Earth StatisticsMass (kg) 5.976e+24Mass (Earth = 1) 1.0000e+00Equatorial radius (km) 6,378.14Equatorial radius (Earth = 1) 1.0000e+00Mean density (gm/cm^3) 5.515Mean distance from the Sun (km) 149,600,000Mean distance from the Sun (Earth = 1) 1.0000

Rotational period (days) 0.99727Rotational period (hours) 23.9345Orbital period (days) 365.256Mean orbital velocity (km/sec) 29.79Orbital eccentricity 0.0167Tilt of axis (degrees) 23.45Orbital inclination (degrees) 0.000Equatorial escape velocity (km/sec) 11.18Equatorial surface gravity (m/sec^2) 9.78Visual geometric albedo 0.37Mean surface temperature 15°CAtmospheric pressure (bars) 1.013Atmospheric compositionNitrogenOxygenOther

77%21%2%

15

MARS Mars is the fourth planet from the Sun and is commonly referred to as the

Red Planet. The rocks, soil and sky have a red or pink hue. The distinct red color was observed by stargazers throughout history. It was given its name by the Romans in honor of their god of war. Other civilizations have had similar names. The ancient Egyptians named the planet Her Descher meaning the red one.

Before space exploration, Mars was considered the best candidate for harboring extraterrestrial life. Astronomers thought they saw straight lines crisscrossing its surface. This led to the popular belief that irrigation canals on the planet had been constructed by intelligent beings. In 1938, when Orson Welles broadcasted a radio drama based on the science fiction classic War of the Worlds by H.G. Wells, enough people believed in the tale of invading Martians to cause a near panic.

Another reason for scientists to expect life on Mars had to do with the apparent seasonal color changes on the planet's surface. This phenomenon led to speculation that conditions might support a bloom of Martian vegetation during the warmer months and cause plant life to become dormant during colder periods.

In July of 1965, Mariner 4, transmitted 22 close-up pictures of Mars. All that was revealed was a surface containing many craters and naturally occurring channels but no evidence of artificial canals or flowing water. Finally, in July and September 1976, Viking Landers 1 and 2 touched down on the surface of Mars. The three biology experiments aboard the landers discovered unexpected and enigmatic chemical activity in the Martian soil, but provided no clear evidence for the presence of living microorganisms in the soil near the landing sites. According to mission biologists, Mars is self-sterilizing. They believe the combination of solar ultraviolet radiation that saturates the surface, the extreme dryness of the soil and the oxidizing nature of the soil chemistry prevent the formation of living organisms in the Martian soil. The question of life on Mars at some time in the distant past remains open.

Other instruments found no sign of organic chemistry at either landing site, but they did provide a precise and definitive analysis of the composition of the Martian atmosphere and found previously undetected trace elements.

16

JUPITER Jupiter is the fifth planet from the Sun and is the largest planet in the solar system.

If Jupiter were hollow, more than one thousand Earths could fit inside. It also contains two and a half times the mass of all the other planets combined. It has a mass of 1.9 x 1027 kg and is 142,800 kilometers (88,736 miles) across the equator. Jupiter possesses 62 known satellites. The four largest are Callisto, Europa, Ganymedeand Io, and were named after Galileo Galilei who observed them as long ago as 1610. The German astronomer Simon Marius claimed to have seen the moons around the same time, but he did not publish his observations and so Galileo is given the credit for their discovery.

Jupiter has a very faint ring system, but is totally invisible from the Earth. (The rings were discovered in 1979 by Voyager 1.) The atmosphere is very deep, perhaps comprising the whole planet, and is somewhat like the Sun. It is composed mainly of hydrogen and helium, with small amounts of methane, ammonia, water vapor and other compounds. At great depths within Jupiter, the pressure is so great that the hydrogen atoms are broken up and the electrons are freed so that the resulting atoms consist of bare protons. This produces a state in which the hydrogen becomes metallic.

Colorful latitudinal bands, atmospheric clouds and storms illustrate Jupiter's dynamic weather systems. The cloud patterns change within hours or days. The Great Red Spot is a complex storm moving in a counter-clockwise direction. At the outer edge, material appears to rotate in four to six days; near the center, motions are small and nearly random in direction. An array of other smaller storms and eddies can be found through out the banded clouds.

Aurora emissions, similar to Earth's northern lights, were observed in the polar regions of Jupiter. The auroral emissions appear to be related to material from Io that spirals along magnetic field lines to fall into Jupiter's atmosphere. Cloud-top lightning bolts, similar to superbolts in Earth's high atmosphere, were also observed.

17

Jupiter's Ring

Unlike Saturn's intricate and complex ring patterns, Jupiter has a simple ring system that is composed of an inner halo, a main ring and a Gossamer ring. To the Voyager spacecraft, the Gossamer ring appeared to be a single ring, but Galileo imagery provided the unexpected discovery that Gossamer is really two rings. One ring is embedded within the other. The rings are very tenuous and are composed of dust particles kicked up as interplanetary meteoroids smash into Jupiter's four small inner moons Metis, Adrastea, Thebe, and Amalthea. Many of the particles are microscopic in size.

The innermost halo ring is toroidal in shape and extends radially from about 92,000 kilometers (57,000 miles) to about 122,500 kilometers (76,000 miles) from Jupiter's center. It is formed as fine particles of dust from the main ring's inner boundary 'bloom' outward as they fall toward the planet. The main and brightest ring extends from the halo boundary out to about 128,940 kilometers (80,000 miles) or just inside the orbit of Adrastea. Close to the orbit of Metis, the main ring's brightness decreases.

The two faint Gossamer rings are fairly uniform in nature. The innermost Amalthea Gossamer ring extends from the orbit of Adrastea out to the orbit of Amalthea at 181,000 kilometers (112,000 miles) from Jupiter's center. The fainter Thebe Gossamer ring extends from Amalthea's orbit out to about Thebe's orbit at 221,000 kilometers (136,000 miles).

Jupiter's rings and moons exist within an intense radiation belt of electrons and ions trapped in the planet's magnetic field. These particles and fields comprise the jovian magnetosphere or magnetic environment, which extends 3 to 7 million kilometers (1.9 to 4.3 million miles) toward the Sun, and stretches in a windsock shape at least as far as Saturn's orbit - a distance of 750 million kilometers (466 million miles).

18

Jupiter StatisticsMass (kg) 1.900e+27Mass (Earth = 1) 3.1794e+02Equatorial radius (km) 71,492Equatorial radius (Earth = 1) 1.1209e+01Mean density (gm/cm^3) 1.33Mean distance from the Sun (km) 778,330,000Mean distance from the Sun (Earth = 1) 5.2028

Rotational period (days) 0.41354Orbital period (days) 4332.71Mean orbital velocity (km/sec) 13.07Orbital eccentricity 0.0483Tilt of axis (degrees) 3.13Orbital inclination (degrees) 1.308Equatorial surface gravity (m/sec^2) 22.88Equatorial escape velocity (km/sec) 59.56Visual geometric albedo 0.52Magnitude (Vo) -2.70Mean cloud temperature -121°CAtmospheric pressure (bars) 0.7Atmospheric compositionHydrogenHelium

90%10%

19

SATURN Saturn is the sixth planet from the Sun and is the second largest in the solar system with an

equatorial diameter of 119,300 kilometers (74,130 miles). Much of what is known about the planet is due to the Voyager explorations in 1980-81. Saturn is visibly flattened at the poles, a result of the very fast rotation of the planet on its axis. Its day is 10 hours, 39 minutes long, and it takes 29.5 Earth years to revolve about the Sun. The atmosphere is primarily composed of hydrogen with small amounts of helium and methane. Saturn is the only planet less dense than water (about 30 percent less). In the unlikely event that a large enough ocean could be found, Saturn would float in it. Saturn's hazy yellow hue is marked by broad atmospheric banding similar to, but fainter than, that found on Jupiter.

The wind blows at high speeds on Saturn. Near the equator, it reaches velocities of 500 meters a second (1,100 miles an hour). The wind blows mostly in an easterly direction. The strongest winds are found near the equator and velocity falls off uniformly at higher latitudes. At latitudes greater than 35 degrees, winds alternate east and west as latitude increases.

Saturn's ring system makes the planet one of the most beautiful objects in the solar system. The rings are split into a number of different parts, which include the bright A and B rings and a fainter C ring. The ring system has various gaps. The most notable gap is the Cassini [kah-SEE-nee] Division, which separates the A and B rings.Giovanni Cassini discovered this division in 1675. The Encke [EN-kee] Division, which splits the A Ring, is named after Johann Encke, who discovered it in 1837. Space probes have shown that the main rings are really made up of a large number of narrow ringlets. The origin of the rings is obscure. It is thought that the rings may have been formed from larger moons that were shattered by impacts of comets and meteoroids. The ring composition is not known for certain, but the rings do show a significant amount of water. They may be composed of icebergs and/or snowballs from a few centimeters to a few meters in size. Much of the elaborate structure of some of the rings is due to the gravitational effects of nearby satellites. This phenomenon is demonstrated by the relationship between the F-ring and two small moons that shepherd the ring material.

Radial, spoke-like features in the broad B-ring were also found by the Voyagers. The features are believed to be composed of fine, dust-size particles. The spokes were observed to form and dissipate in the time-lapse images taken by the Voyagers. While electrostatic charging may create spokes by levitating dust particles above the ring, the exact cause of the formation of the spokes is not well understood. Saturn has 30 named satellites and more continue to be discovered.

20

Saturn StatisticsMass (kg) 5.688e+26Mass (Earth = 1) 9.5181e+01Equatorial radius (km) 60,268Equatorial radius (Earth = 1) 9.4494e+00Mean density (gm/cm^3) 0.69Mean distance from the Sun (km) 1,429,400,000Mean distance from the Sun (Earth = 1) 9.5388Rotational period (hours) 10.233Orbital period (years) 29.458Mean orbital velocity (km/sec) 9.67Orbital eccentricity 0.0560Tilt of axis (degrees) 25.33Orbital inclination (degrees) 2.488Equatorial surface gravity (m/sec^2) 9.05Equatorial escape velocity (km/sec) 35.49Visual geometric albedo 0.47Magnitude (Vo) 0.67Mean cloud temperature -125°CAtmospheric pressure (bars) 1.4Atmospheric compositionHydrogenHelium

97%3%

21

URANUS Uranus is the seventh planet from the Sun and is the third largest in the solar system. It was

discovered by William Herschel in 1781. It has an equatorial diameter of 51,800 kilometers (32,190 miles) and orbits the Sun once every 84.01 Earth years. It has a mean distance from the Sun of 2.87 billion kilometers (1.78 billion miles). It rotates about its axis once every 17 hours 14 minutes. Uranus has at least 22 moons. The two largest moons, Titania and Oberon, were discovered by William Herschel in 1787.

The atmosphere of Uranus is composed of 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and other hydrocarbons. Methane in the upper atmosphere absorbs red light, giving Uranus its blue-green color. The atmosphere is arranged into clouds running at constant latitudes, similar to the orientation of the more vivid latitudinal bands seen on Jupiter and Saturn. Winds at mid-latitudes on Uranus blow in the direction of the planet's rotation. These winds blow at velocities of 40 to 160 meters per second (90 to 360 miles per hour). Radio science experiments found winds of about 100 meters per second blowing in the opposite direction at the equator.

Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the solar system's history. Voyager 2 found that one of the most striking influences of this sideways position is its effect on the tail of the magnetic field, which is itself tilted 60 degrees from the planet's axis of rotation. The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet. The magnetic field source is unknown; the electrically conductive, super-pressurized ocean of water and ammonia once thought to lie between the core and the atmosphere now appears to be nonexistent. The magnetic fields of Earth and other planets are believed to arise from electrical currents produced in their molten cores.

Uranus' Rings

In 1977, the first nine rings of Uranus were discovered. During the Voyager encounters, these rings were photographed and measured, as were two other new rings and ringlets. Uranus' rings are distinctly different from those at Jupiter and Saturn. The outermost epsilon ring is composed mostly of ice boulders several feet across. A very tenuous distribution of fine dust also seems to be spread throughout the ring system.

There may be a large number of narrow rings, or possibly incomplete rings or ring arcs, as small as 50 meters (160 feet) in width. The individual ring particles were found to be of low reflectivity. At least one ring, the epsilon, was found to be gray in color. The moons Cordelia and Ophelia act as shepherd satellites for the epsilon ring.

22

Uranus StatisticsDiscovered by William HerschelDate of discovery 1781Mass (kg) 8.686e+25Mass (Earth = 1) 1.4535e+01Equatorial radius (km) 25,559Equatorial radius (Earth = 1) 4.0074Mean density (gm/cm^3) 1.29Mean distance from the Sun (km) 2,870,990,000Mean distance from the Sun (Earth = 1) 19.1914

Rotational period (hours) -17.9Orbital period (years) 84.01Mean orbital velocity (km/sec) 6.81Orbital eccentricity 0.0461Tilt of axis (degrees) 97.86Orbital inclination (degrees) 0.774Equatorial surface gravity (m/sec^2) 7.77Equatorial escape velocity (km/sec) 21.30Visual geometric albedo 0.51Magnitude (Vo) 5.52Mean cloud temperature -193°CAtmospheric pressure (bars) 1.2Atmospheric compositionHydrogenHeliumMethane

83%15%

2%

23

NEPTUNE Neptune is the outermost planet of the gas giants. It has an equatorial diameter of

49,500 kilometers (30,760 miles). If Neptune were hollow, it could contain nearly 60 Earths. Neptune orbits the Sun every 165 years. It has eight moons, six of which were found by Voyager. A day on Neptune is 16 hours and 6.7 minutes. Neptune was discovered on September 23, 1846 byJohann Gottfried Galle, of the Berlin Observatory, and Louis d'Arrest, an astronomy student, through mathematical predictions made by Urbain Jean Joseph Le Verrier.

The first two thirds of Neptune is composed of a mixture of molten rock, water, liquid ammonia and methane. The outer third is a mixture of heated gases comprised of hydrogen, helium, water and methane. Methane gives Neptune its blue cloud color.

Neptune is a dynamic planet with several large, dark spots reminiscent of Jupiter's hurricane-like storms. The largest spot, known as the Great Dark Spot, is about the size of the earth and is similar to the Great Red Spoton Jupiter. Voyager revealed a small, irregularly shaped, eastward-moving cloud scooting around Neptune every 16 hours or so. This scooter as it has been dubbed could be a plume rising above a deeper cloud deck.

Long bright clouds, similar to cirrus clouds on Earth, were seen high in Neptune's atmosphere. At low northern latitudes, Voyager captured images of cloud streaks casting their shadows on cloud decks below.

The strongest winds on any planet were measured on Neptune. Most of the winds there blow westward, opposite to the rotation of the planet. Near the Great Dark Spot, winds blow up to 2,000 kilometers (1,200 miles) an hour.

Neptune has a set of four rings which are narrow and very faint. The rings are made up of dust particles thought to have been made by tiny meteorites smashing into Neptune's moons. From ground based telescopes the rings appear to be arcs but from Voyager 2 the arcs turned out to be bright spots or clumps in the ring system. The exact cause of the bright clumps is unknown.

The magnetic field of Neptune, like that of Uranus, is highly tilted at 47 degrees from the rotation axis and offset at least 0.55 radii (about 13,500 kilometers or 8,500 miles) from the physical center. Comparing the magnetic fields of the two planets, scientists think the extreme orientation may be characteristic of flows in the interior of the planet and not the result of that planet's sideways orientation or of any possible field reversals at either planet.

Neptune Statistics

24

Discovered by Johann Gotfried GalleDate of discovery September 23, 1846Mass (kg) 1.024e+26Mass (Earth = 1) 1.7135e+01Equatorial radius (km) 24,746Equatorial radius (Earth = 1) 3.8799e+00Mean density (gm/cm^3) 1.64Mean distance from the Sun (km) 4,504,300,000Mean distance from the Sun (Earth = 1) 30.0611

Rotational period (hours) 16.11Orbital period (years) 164.79Mean orbital velocity (km/sec) 5.45Orbital eccentricity 0.0097Tilt of axis (degrees) 29.56Orbital inclination (degrees) 1.774Equatorial surface gravity (m/sec^2) 11.0Equatorial escape velocity (km/sec) 23.50Visual geometric albedo 0.41Magnitude (Vo) 7.84Mean cloud temperature -193 to -153°CAtmospheric pressure (bars) 1-3Atmospheric compositionHydrogenHeliumMethane

85%13%

2%

25

PLUTO There are nine planets in our Solar System. Some of them are large, like Jupiter or

Saturn. Others are medium-sized, like our own Earth. And one planet is the smallest planet: Pluto. Here are some interesting facts about this lonely little planet on the edge of our Solar System.

Pluto is very far away. It averages about 3.5 billion miles from the Sun, and about 3.4 billion miles from Earth. Pluto is so far away that scientists here on Earth have trouble seeing it, even with our best telescopes--we didn’t even find it until 1930! If we tried to fly there, even our fastest spaceships would take more than 600 years to reach Pluto.

Even if we could reach Pluto, it might not be worth the trip. Pluto is small, cold, and lifeless. It is a giant ball of ice and rock floating so far from the Sun that almost none of the Sun’s heat reaches it. The surface of Pluto is made entirely of ice, and the surface temperature remains below -350 degrees Fahrenheit! That’s cold!

Pluto is also dark. Because it is so far from the Sun, it does not get all the light that we get here on Earth. Even during the day, the sky of Pluto is as dark as nighttime on Earth. From Pluto’s surface, the Sun looks like a very bright star.

While we may visit Pluto one day, it is unlikely that we will ever live there. Because of its size, Pluto has very low gravity and a very thin atmosphere. The atmosphere is full of nitrogen and carbon monoxide, gasses which we humans cannot breather. Without a good atmosphere, especially one with lots of oxygen, no Earth life could live on Pluto’s surface.

In addition, Pluto is so cold that we would need amazingly powerful heaters, not to mention a good supply of warm blankets, if we ever hoped to live there. Even Pluto’s warmest days are almost three times colder than the coldest days on Earth!

Pluto has one moon that we know of. It is called Charon, and it is half the size of Pluto. Charon is just as cold and lifeless as Pluto. Charon is so small that we could not even see it until 1978, when we developed better telescopes.

Sometimes. In fact, most of the time! But sometimes, Pluto and another planet, Neptune, cross paths, like two trains on crossed tracks. Once every 248 years, for about 20 years, Neptune is further away from the Sun than Pluto. Then the two planets cross paths again, and Pluto becomes the farthest planet once more. The last time this happened was in 1979, and it lasted until 1999. Pluto and Neptune won’t cross paths again until the year 2247, which is almost 250 years from now.

Pluto StatisticsDiscovered by Clyde W. Tombaugh

26

Date of discovery February 18, 1930Mass (kg) 1.27e+22Mass (Earth = 1) 2.125e-03Equatorial radius (km) 1,137Equatorial radius (Earth = 1) 0.1783Mean density (gm/cm^3) 2.05Mean distance from the Sun (km) 5,913,520,000Mean distance from the Sun (Earth = 1)) 39.5294Rotational period (days) -6.3872Orbital period (years) 248.54Mean orbital velocity (km/sec) 4.74Orbital eccentricity 0.2482Tilt of axis (degrees) 122.52Orbital inclination (degrees) 17.148Equatorial surface gravity (m/sec^2) 0.4Equatorial escape velocity (km/sec) 1.22Visual geometric albedo 0.3Magnitude (Vo) 15.12Atmospheric compositionMethaneNitrogen

0.3

BIBLIOGRAPHY27

1)Success Science UPSR – Oxford Fajar

2)Science Year 4 Text Book

3) Web – www.solar system.com.my

28

THE END

29