Science in English Grade 5

Assumption College Primary SectionSemester 2 / 2010

Unit 1 The Sun, Earth and

MoonBy Ms. Pathitta Tangporntirakul

The stars and the SunA star is a huge ball of hot glowing gases, mainly hydrogen and helium. It gives out heat and light. The Sun is also a star. It is the star nearest to us. That is why it appears so big as compared to the other stars. All stars other than the Sun appears as twinkling points of light in the night sky. They cannot be seen during the day because of the lights of the Sun.

Without the Sun’s heat and light, the Earth would have been very cold. There would have been no life on the Earth.The Sun weights about 300,000 times more than theEarth. Its surface temperature is about 6,000° c.The temperature at its centre is about 15,000,000 ° c.It is about 4.5 billion (4,500,000,000) years old.It will continue to give heat and light for another billion years. After that it will run out of hydrogen and die.

The planets and the solar system

A planet is a big ball of rocks. It does not give out itsown heat and light. Our Earth is also a planet.

The Earth and seven other planets move around the Sun. The planets appear bright because they reflect the light of the Sun. The eight planets, in order of increasing distances from the Sun are as follows.

MercuryVenusEarthMarsJupiterSaturnUranusNeptune

These planets move around the Sun in fixed paths called orbits. Six of these planets have smaller objects calledmoons that move around them.

Our Earth has only one moon. Mars has two moons.Jupiter, Saturn, Uranus and Neptune have many moons.Mercury and Venus do not have any moons.

The Sun, the planets and their moons belong to a family of objects called the solar system.

Sun - The Sun is a star at the center of our Solar System.

Mercury - Mercury is the planet closest to the Sun.

Venus - Venus is the second planet from the Sun. It is the hottest planet.

Earth - Earth is the third planet from the Sun and the planet we live on.

Mars - Mars is a red planet and the fourth planet from the Sun.

Jupiter - Jupiter is the fifth planet from the Sun. This gas giant is the largest planet.

Saturn - Saturn is the sixth planet from the Sun. This gas giant has large, beautiful rings.

Uranus - Uranus is a gas giant and is the seventh planet from the Sun.

Neptune - Neptune is a gas giant and is usually the eighth planet from the Sun.

MercuryMercuryOur Fastest Planet

• The closest Planet to the Sun.• Only a little larger than our

moon.• It is covered by dust, rocks,

and craters.• It takes 59 days for it to

rotate once around its axis.• Mercury can reach a high of

800 degrees and a low of about 300 degrees Fahrenheit.

VenusVenusOur Hottest Planet

• It takes longer to rotate once around its axis than to revolve once around the sun.

• On Venus a day is slightly more than a year.

• About the same size as Earth.• Has mountains, valleys, and

plains. • The heat is about 450 degrees

Celsius.• Has no water. • Life as we know it could not

survive here. Only rocks can handle the high temperature and crushing pressure.

EarthEarthOur Mother PlanetOur Mother Planet

• 70% of its surface is water& the other 30% is land.

• It’s tilt causes the seasons on the planet.

• Earth is the only planet in the universe which is known to support life.

• Earth is almost five billion years old.

• The center of the Earth, its core, is molten.

• Earth is the only planet in the Solar System known to be geologically active.

MarsMarsOur Angry Red PlanetOur Angry Red Planet

• The largest volcano in the Solar System is on Mars, called Olympus Mons.

• Mars has seasons like Earth. This is caused by the tilt of the planet's axis, at a similar angle to the tilt of Earth's axis

• Rocks from Mars have landed on Earth from meteorite impacts blasting debris through space.

• The average temperature on Mars is about -67 °F.

Jupiter Jupiter Our Largest PlanetOur Largest Planet

• Earth could fit into Jupiter over 1300 times!

• Jupiter is made up almost entirely of gas.

• Jupiter's famous Red Spot is a great storm that has raged for at least four hundred years.

• Jupiter has a thin set of rings, hardly visible from Earth.

• Jupiter has the strongest pull of gravity in the Solar System.

• If we were able to stand on the surface of Jupiter, we would weigh three times as much as we would on Earth.

SaturnSaturnRings of BeautyRings of Beauty

• Saturn is the second largest planet.• The many moons of Saturn are as

different as fire and ice. There are at least 24 of them.

• Saturn's rings are believed to be the particles of an old moon orbiting the planet, smashed apart in a collision about 50 million years ago. A year on Saturn would take almost thirty Earth years.

• Saturn is twice as far away from the Sun as Jupiter is.

UranusUranus

• It takes just over 84 years on Earth for Uranus to orbit the Sun.

• Uranus is the only planet in our solar system to rotate on its side.

• If we were able to see Uranus' moons orbiting the planet, they would go over and under the planet like lights on a ferris wheel.

• Uranus' pale blue color is caused by the methane in its atmosphere which filters out red light.

NeptuneNeptune• Neptune sometimes orbits the Sun

further away than Pluto making it the most distant planet in the Solar System.

• Since its discovery in 1846, Neptune has not yet completed a full orbit. In fact, it takes 165 years for the planet to go around the Sun.

• Neptune has the strongest winds in the Solar System, and a dark spot, similar to Jupiter's Great Red Spot.

The Earth is a huge sphere. Its surface is made up of rocks, soil and water. It is surrounded by a layer of air called atmosphere.

We live on the outer surface of the Earth, which is cool and has conditions suitable for life. This outer surface is called the crust. But the Earth is not the same deep inside. It is very hot inside. Below the crust is the mantle, which is made up of very hot molten rock. In the centre is the core. It is the hottest part of the earth. It consists of molten metals.

The Earth has a diameter of approximately 13,000 km. Its distance from the Sun is approximately 150 million km.

The Earth is unique because it is the only planet on which life exists. This is because the conditions on the Earth are favourable for life to exist.

Plants prepare food by photosynthesis usingmaterials from the soil, carbon dioxide from the air and sunlight.

All other living things directly or indirectly eat thisfood. The materials necessary for plants to make food are present on the Earth.

The Earth is at just the right distance from the Sun, for it to have the right temperature for life to survive. The average temperature on theEarth is 14° c, which is suitable for living things.If the Earth had been closer to the Sun, like Mercury or Venus, it would have been too hot for life to survive. If it had been far off, like Jupiter or Saturn,it would have been too cold.

The Earth is the only planet on which water is available in liquid form. As you know, water isessential for living things. In fact life first emerged on the Earth in water.

The Earth is the only planet with an atmospherecontaining oxygen, which is essential for life. Plants, human and other land animals get oxygen from air. Plants and animals living in water also need oxygen. They get it from oxygen dissolved in water.

The Earth rotates on its axis.Observe a rotating top. It appears to spin around a linepassing through its centre.

The Earth spins in a similar way, around a line passing through its centre. This imaginary line passes through the north and south pole of the Earth. It is called the axis of rotation. This spinning movement of the Earth is calledrotation.

The rotation of the Earth causes dayAnd night.

The side of the Earth which faces the Sun has day. The side which faces away has night. As the Earth rotates, day and night follow each other. It takes 24 hours for the Earth to complete one rotation. That is why one day and one night are of 24 hours.

The Earth moves around the Sun in a fixed path called orbit. This movement of the Earth is calledRevolution. The Earth revolves around the Sun once in about 365 days or 1 year. This revolution causes the changing of the seasons.

The Moon is a ball of rocks, about one quarter the size of the Earth. It is 384,400 km away from the Earth, and is our nearest neighbor in space. That it why it appears so big from the Earth. Although the Moon is the brightest object in the night sky, it does not give out light of its own.

It reflects the light of the Sun.

There is no life on the Moon. It does not have any water, and its surface is covered with alayer of dust. It has mountains and huge round pits called craters on its surface. The mountainsand craters can be seen from the Earth througha telescope. There is no atmosphere surrounding the Moon. So there are no winds,clouds and rain.

The Moon revolves around the Earth in the same way as the Earth revolves around theSun. It takes 28 days, or nearly a month, to make one complete revolution around the Earth. The Moon is the only natural satellite of the Earth. A satellite of a star or planet isan object that goes around the star or planet.Natural satellites of planets are known as moons.

The Moon, as seen from the Earth, appears tochange its shape everyday – from a thin crescentto the full moon. This is because we only see thepart of the Moon that reflects the light of the Sunto us. The rest of the Moon is dark. These different shapes of the Moon, as seen from the Earth, are called phases of the moon.

New Crescent Half Gibbous Full

• When the side of the Moon facing us gets no sunlight at all, we cannot see the Moon.We call this a New Moon(day1). • As the Moon moves along its orbit, a small portion of the side facing us gets sunlight, andwe can see the Crescent Moon (day3).• In a week we can see half of the Moon(day7).• After 3 more days we see three-quarters ofthe Moon. This is the Gibbous Moon(day10).• In two weeks the entire side facing us gets sunlight. We can then see the Full Moon(day14).• After this, the phases reverse.

Three Americans, Neil Armstrong, Edwin Aldrinand Michael Collins were the first to visit the Moon in a spacecraft called Apollo11. Neil Armstrong and Edwin Aldrin stepped onThe moon on 21 July 1969.

Humans have been successful in placing their own satellites around the Earth. These satellites are sent up in rockets.They revolve around the Earth, and are usedfor various purposes. They are know asartificial satellites.

One of the most important uses of satellitesis communication.Communication satellites are used to relaytelevision and radio programs. They are alsoused for sending telephone signals to far offplaces. Weather satellites are used to forecastthe weather.

Some satellites are used to photograph the Earth from above – this gives valuable information about natural resources. Other are used to study stars and planets. One such satellites is the Hubble Telescope, which is placed 500 km. above the surface of the Earth.

The first satellite sent up in space by Thailand was a communication satelliteThaicom1. 17 December 1993

GAMES