Solar System


The Sun is a star, without it nearby, Earth would be as cold and lifeless as Pluto. The heat of the Sun controls our weather. It puts power behind winds and evaporates water to make clouds and rain.

The Sun has been shining for 5000 million years. Its surface is 6000? C and looks like
it’s on fire. The Sun is like a nuclear-fusion bomb. Deep down inside its super-hot core, it smashes 600 million tones of hydrogen atoms together every second, turning them into heavier helium atoms. The energy released by this atom smashing, escapes into space as light and heat. The Sun is 1 392 000 km in diameter.


Mercury is the closest planet to the Sun, and rushes around it every 88 days. It
takes about two-thirds of that time just to spin around once on its axis. Due to
its long day and short year, sunrises on Mercury occur 176 days apart.
Temperatures on Mercury can soar to 430? C and can drop to ?180? C. Mercury is
4879 km in diameter, and is 58 million km from the sun.                  
At a constant temperature of 460? C (day and night), Venus is the hottest planet in the Solar System. Venus suffers from the greenhouse effect gone crazy. A thick layer of carbon dioxide traps solar energy and heats up Venus in the same way a blanket keeps you warm at night.
What’s even worse, is that acid rain falls from its clouds of sulphuric acid. Venus is 12104 km in diameter, and is 108 million km from the Sun.
Earth is the third planet from the Sun, and like all the planets, orbits the Sun.
It’s 12 756 km in diameter, an is 150 million km from the Sun. Also, Earth spins on its axis. Earth is unique because it is the only planet with the right conditions for life.

Planets closer to the Sun are too hot for living things. Those further away from the Sun are too cold. Some planets have an atmosphere too poisonous to breathe or no atmosphere at all. Some, like Saturn and Jupiter, have no surface to walk on. Earth is the only planet with the right conditions for life.

Earth is a rocky planet, like Mercury, Venus and Mars, but is much more active. Heat from deep down inside our planet forces volcanoes to erupt, earthquakes to shake the surface, and continents to slowly shift their position over time. Meanwhile, wind, ocean waves and rain gradually reshape the landscape.

The Moon is about one-quarter the size of Earth and has only one- sixth as much gravity. Due to the lack of gravity, you could jump six times higher than on Earth.

The Moon has absolutely no air. There is no oxygen to breathe, no liquid water, no pants and no life of any kind. In the sunshine, the
Moon’s surface can be as hot as 100? C, and at night, the temperatures can plunge to -150? C. Lunar nights last 2 weeks.

Since the Moon has no wind or rain, footprints will still be there millions of years from now.

The Moon was created about 4500 million years ago when a small planet crashed into the Earth. The impact ripped apart the intruder planet and blasted huge chunks of the
Earth’s upper layers into space. The rocky debris from the intruder planet and from Earth joined together and formed the Moon.

MARSMars is the planet most like Earth. A day on Mars is only 40 minutes longer than a day on Earth. It also has seasons of summer and winter. Millions of years ago, Mars was just like Earth. Rivers flowed across the land. An ocean might have covered half the Planet, and life could have flourished.

On Mars the temperature of a
summer’s day reaches only 0? C, but at night, it plunges to ?80? C, that’s as cold as Antarctica in winter. During the winter on Mars, there are bone-chilling temperatures, of about ?125? C. This is so cold that the air at the north and south poles of Mars freezes. Mars is 6794 km in diameter and is 228 million km from the Sun.

Mars has two small moons that rush around it. Deimos, the outer moon, is only 15 km long
that’s no bigger than a small city. Phobes, the inner moon, is a potato shaped moon 27 km long. Both moons could be asteroids captured into orbit by Mars? gravity millions of years ago.

JUPITERJupiter is the biggest of all the Planets and is made up of hydrogen and helium gases. These same gases make up the Sun, but Jupiter would have to contain 80 times more gas before it could shine like a star.

Regardless of its size, Jupiter spins faster than every other Planet ?
Jupiter’s day lasts only 10 hours. Due to its speedy spin, Jupiter can whip clouds into storms as big as a continent on Earth. Winds can rage up to 500 km per hour with huge bolts of lightning crackling in the thunderclouds. Jupiter has a diameter of 142 980 km and is 778 million km from the Sun.

Jupiter’s gravity is so strong that it controls a family of 16 moons. Twelve are the size of small asteroids. Four of
Jupiter’s moons are larger than Pluto.

SATURNSaturn is the second largest Planet and if you took its rings away, it would look just like Jupiter. Saturn is also made up of hydrogen and helium gases. It spins quickly, too, with its day lasting only 10 hours and 40 minutes.

Saturn’s clouds are less colorful than Jupiter’s because it is further away from the Sun ? and colder. Temperatures in
Saturn’s clouds of ammonia ice-crystals hover at -135? C. On Saturn winds can blow even stronger than on Jupiter. In some places,
Saturn’s winds roar at 1300 km per hour, that’s 11 times faster than a hurricane on Earth. Saturn has a diameter of 120 540 km and is 1 492 million km from the Sun.

The most impressive sight on Saturn would be the thousands of rings that circle it. These rings are a blizzard of snowballs. From a long distance, that rings look solid, but from close-up, they would look like millions of ice chunks the size of hailstones and snowballs. If you packed all the ring particles together, you could make a snowball about 100km across.

Saturn has 18 moons. The biggest moon is Titan, which is the 2nd largest moon in the Solar System. Titan is the only moon that has a thick atmosphere. You would not be able to see through
Titan’s dense, orange clouds.

URANUSUranus was discovered by William Herschel in 1781. It’s 51 120 km in diameter and is 2875 million km from the Sun. Neptune, the 8th Planet, was spotted in 1846 by Johonne Galle and Heinrich D Arrest.
It’s 49 530 km in diameter and is 4504 million km from the Sun.

Uranus and Neptune are in many ways twins. They are both four times bigger than Earth. Each is circled by dark, thin rings, and both have an atmosphere choked up with poisonous methane gas. Beneath this atmosphere lies a thick, slushy layer of ice and water.

NEPTUNENeptune has 8 moons with Triton being the largest. The temperature on Triton plunges to -235? C.
That’s as cold as any moon or Planet in the Solar System.
Uranus and Neptune do have some differences. If you kept going past
Neptune’s layer of slush, you might come to a hot core. Astronomers believe heat from this core rises, stirs up the cloud tops and lets rip strong winds and large storms. The weather in
Uranus’s atmosphere is clam in comparison. At the center of Uranus is most probably a cold core.

Compared to other Planets, Uranus is tilted over on its side. For much of
Uranus’s year, one of its two poles faces towards the Sun. One theory suggests that millions of years ago, an asteroid hit Uranus so hard that he Planet toppled over.


Pluto lies at the edge of the Solar System and is the smallest Planet. It?s 2300 km in diameter and is 5916 km from the Sun.

Pluto?s landscape is a patchwork of light, frost-covered regions and dark, frost-free regions. Made up of frozen nitrogen and methane, the frost covering is chilled to -238? C. The frost-free areas are a few degrees warmer. This difference in temperature whips up cold winds in the thin nitrogen-methane.

Astronomers once believed that a 10th Planet orbited beyond Pluto. New calculations show that this Planet probably
doesn’t exist. But thousands of small ice comets do orbit beyond Pluto, in an area named the Kuiper Belt. Instead of being the Solar
System’s smallest Planet, Pluto might belong to the Kuiper Belt and be the largest object in it.

All the other Planets in the Solar System orbit the Sun in the same flat plane, but tiny
Pluto’s orbit is tilted into a long oval shape. Pluto has a 248-year orbit, and for most of it is the outermost Planet, but sometimes it crosses over the orbit of Neptune, making Neptune the furthest Planet from the Sun.