Day and Night
Day and Night :
Earth's rotation on its axis causes day and night.
As Earth spins, sunlight only falls on one-half of the planet. This means it is daytime on that side of Earth. On the other side, it is night. This way we have Day and Night.
The apparent movement of the Sun across the sky is actually due to the rotation of our Earth. The Sun always appears to rise in the east and set in the west regardless of where you are on Earth.
When the Sun rises, that part of the Earth is turning to face the Sun. When the Sun sets, that part of the Earth is turning away from the Sun. The Sun itself doesn't actually rise or set. Each planet spins around or rotates on its axis.
Earth spins around at a speed of 1 600 km/h. Earth takes almost 24 hours to complete one rotation around the Sun. Because each rotation takes slightly less than 24 hours the calendar needed adjusting. Leap years add an extra day, the 29th February, to the calendar every four years so that the calendar aligns with Earth's motion around the Sun.
Moon Phases :
We see the Moon because sunlight is reflected from its surface. As the Moon orbits Earth and as Earth orbits the Sun, we see different amounts of the Moon's sunlit face. These are known as the phases of the Moon.
New Moon : The Moon in between Earth and The Sun and The Moon’s unlit side is facing Earth.
Waxing Moon : Less than one-half of the Moon is lit by direct sunlight.
First Quarter : One-half of the Moon is lit by direct sunlight.
Waxing Gibbous : More than one-half of the Moon is lit by direct sunlight.
Full Moon : Two weeks after the New Moon, the Moon os halfway through its orbit. The Moon’s sunlit side is looking Earth.
Waning Gibbous : More than one-half of the Moon is lit by direct sunlight.
Last Quarter : One-half of the Moon is lit by direct sunlight.
Waning Crescent : Less than one-half of the Moon is lit by direct sunlight.
AMAZING FACTS about Our Solar System :
The solar system includes the Sun, the nine planets and their 158 presently known moons. It also includes asteroids, meteoroids, comets and interplanetary dust. Come on a journey and travel through our solar system. Visit all nine planets and discover if NEOs are a threat to Earth. This way we have Day and Night.
The inner solar system is separated from the outer by the asteroid belt.
The solar system is port of the Milky Way galaxy which is a barred-spiral galaxy.
There were 9 planets in the Solar System until 2006 when the International Astronomical Union decided that Pluto could no longer be considered a planet due to its size being smaller than our moon.
If all the planets were joined together, the Sun would still be more than 700 times bigger. It contains over 99% of the solar system's mass.
It takes two million years for gamma rays produced in the core of the Sun to reach its surface.
The Sun is the largest object the solar system. It is about 332 950 times more massive than Earth.
The relationship between the Sun and the Earth drives the seasons, currents in the ocean, weather and climate.
The Sun has been burning for about five billion years and will bum for another five billion.
If you stood on Venus, the atmospheric pressure would be the same as if you were 900 metres underneath an ocean on Earth.
Much of the surface of Venus, including craters, has been covered in lava from previous eruptions.
Mercury and Venus are the only two planets in our solar system that don't have moons.
Mercury has the greatest variation in surface temperature of any planet in the solar system — can be over 600 degrees Celsius.
Because there is no wind or rain on the Moon, any footprints left by the astronauts should remain for millions of years.
It is thought that Earth was hit by a large object and the debris that was ejected into space joined together to form the Moon.
The official Latin name for planet Earth is Terra. It is named after the Roman goddess of fertility and growth - Terra Mater.
The Moon is the only other planet or satellite in the solar system that humans hove set foot upon.
The length of each Martian season is almost twice as long as a season on Earth.
Mars has the least hostile environment of all the other planets in the solar system.
The surface area of Mars is approximately equal to that of Earth's dry land as Mars does not have any oceans.
Mars has two small moons. They have uneven shapes and may originally have been asteroids.
After the Sun, the Moon and Venus, Jupiter is usually the fourth brightest object in the sky.
Saturn is almost exactly the same as Jupiter, just smaller. The only striking difference is the rings around Saturn.
Saturn's rings are thought to be particles of an old moon which was smashed to pieces in a collision million of years ago.
Jupiter is made of hydrogen and helium gases which also make up the Sun. If Jupiter had been any bigger, it could have become a star.
It takes 84 Earth years for Uranus to complete one full orbit around the Sun.
The Kuiper Belt contains many comets, asteroids and other small bodies made largely of ice.
As its orbit is so for from the sun, Neptune receives very little heat - in fact the uppermost regions of its atmosphere are -218 degrees Celsius.
A comet's tail can be millions of kilometres long.
Over 9 000 asteroids hove been located and named.
An asteroid, colled Ido, has its own moon called Dactyl.
Halley's comet lost visited Earth in 1986
Astronomers look in space for asteroids or meteorites that might be headed towards Earth.
Today, in the United States and Australia, we can still see craters that are the result of meteorites hitting Earth.
Huge asteroids like the one that caused the extinction of the dinosaurs collide with Earth about once every 100 million years. That asteroid was 15 km wide.
When small fragments of cosmic debris, often left over from a passing comet, enter Earth's atmosphere at high speed we get a meteor shower.
In some regions of the planet, like India, people refer to wet and dry seasons instead of the four seasons.
When it is summer in the Southern Hemisphere, it is winter in the Northern Hemisphere and vice versa.
When it is spring and autumn, neither hemisphere is tilted toward the Sun. This way we have Day and Night.
Nights on average are shorter than days. This is because even when then Sun has gone down, its light still reaches the ground, because of the way it passes through the atmosphere.
The Moon's surface doesn't give off any light. Rather it reflects the light of the Sun. This way we have Day and Night.
