The Solar System

Author:Jyotit KaushalClass VII - E

The Universe

The UNIVERSE consits of everything that we know : stars, planets , rocks , people and so on.

It even includes empty spaceAll the visible matter in the

Universe is contained in galaxies.

Stars STARS are giant

spinning balls of hot gases .

They vary enormously in size (Betelgeuse in the constellation of Orion is 800 times the size of the Sun),and by the amount of light they give.

SUNThe Sun is a star, just one

of billions stars in the Milky Way Galaxy.

1, 400, 000 Earths could fit inside it, it is below the size of the star.

The Sun consists almost of hydrogen and helium.

Temperature is about 15, 00, 00, 000 degree C.

Mercury is the second smallest planet in the Solar System and the closest planet to the Sun.

It is difficult to spot from Earth: it is low on the horizon in the dawn or twilight sky.

MERCURY

Mercury Datafile

Diameter: 4878 KmAverage density:5.4 Surface gravity: 0. 38Atmosphere: traces of

heliumNumber of moons: none

VENUSVenus is the most

inhospitable of the inner planets.

It has a constant surface temperature hotter than the melting point of lead

The air pressure is about 90 times than the Earth

The thick clouds that surround it are made of deadly sulphuric acid.

Venus datafile

Diameter: 12,105Average density: 5.2Surface gravity: 0.9Number of moons:

none

EARTHEarth is the only world in

the Solar System which has liquid water on its surface, essential for life to exist

Earth’s distance from the Sun produces exactly the right temperature range.

Its atmosphere traps enough warmth to avoid extremes.

Earth datafile

Diameter: 12, 756Density: 5.5Number of moons: 1

MARSMars is the fourth planet

from the Sun. It is known as the Red

Planet because of the reddish color of Planet the dust that covers it, although sometimes dark areas of rock show up when storms blow away the dust

Dry river beds and old seashores prove that water once flowed at Mars.

Mars Datafile

Diameter: 6797 Average density: 3.9Number of moons:

none

JupiterJupiter is the largest of all the

planets. It is big enough to contain all

the planets in it together. Known as a “gas giant” because of it thick gassy outer layer, Jupiter has many moons and some of faint rings made of dark grains of dust.

The colourful bands of red, white, brown and yellow on its surface are actually clouds in Jupiter’s swirling, stormy atmosphere.

Jupiter’s datafile

Diameter: 142, 884 km

Average density: 1.3Surface gravity:2.64Number of moons: 63

Jupiter’s first and second largest moons

Ganymede Callisto

Jupiter’s third and fourth largest moons

Lo Europa

SaturnSaturn is the second largest

planet. All four gas giants have ring

systems, but whereas those of Jupiter, Uranus and Neptune are faint and narrow, Saturn’s are bright and wide.

The rings reach out 247, 000 km across space, a distance almost equals to that between Earth and Moon, or five times the radius of Saturn.

Saturn’s datafile

Diameter: 120, 536 kmDensity: 0.7Surface gravity: 1.16Number of moons: 49

Saturn’s major moonsTitan Mimas

Uranus Uranus in 1781 by German

astronomer William Herschel.

It was the first planet to be discovered using the telescope. We know that Uranus is titled at 98degree, meaning that it orbits the Sun almost on its side.

Each pole has some 42 years of continuous daylight, followed by 42 years of darkness.

Uranus datafile

Diameter: 51, 118Density: 1.3Surface gravity: 1.17Number of moons: 27

Uranus’s brightest moon “Ariel”

NeptuneLittle Was Known about

Neptune since its discovery in 1846 by astronomers John Couch Adams and Urbain Le Verrier, until Voyager 2 paid it a visit in 1989.

We know that Neptune is a featureless globe, streaked fast-moving clouds and the occasional storm. It also has four extremely faint, dark, icy rings.

Neptune’s datafile

Diameter: 50,538Density: 1.77Surface gravity: 1.2Number of moons: 13

Neptune’s largest moon Triton

AsteroidsThousands of small,

irregular shaped objects, called asteroids, orbit the Sun between Mars and Jupiter. More than 4000 have been discovered and named.

The largest, Ceres, measuring about 1000 across, has now been reclassified as a dwarf planet.

CometsComets are lumps of ice and

rock, only a few kilometers across, that orbit the Sun.

As they near the Sun, their tails start to grow, eventually extending millions of kilometers into space.

They always point away from the Sun. There is a straight gas tail and a broader, curved dust tail.