Our planet, called Earth, is a ball of rock traveling about 67,000 miles an hour through space. Earth is moving around a star, called the Sun. The pulling power, or gravity, of the Sun keeps the Earth on an elliptical (oval-shaped) course. The time it takes the Earth to make one complete orbit of the Sun is called a year.
PLANET EARTH FACT FILE
Age of the Earth: 4.5 billion years old;
Diameter at the Equator: 7,926 miles across;
Diameter at the Poles: 7,900 miles across;
Circumference at the Equator: 23,627 miles around;
Weight (mass) of the Earth: 6.6 sextillion tons;
Average surface temperature: 59°F;
Rotational speed at the Equator: 995 mph.
The Earth is a ball spinning on an axis, so places at the Equator spin much faster than at the North and South Poles.
MOON FACT FILE
A moon is a ball of rock that orbits a planet. Moons are sometimes called satellites. The Earth has one moon. Length of Moon’s orbit: The Moon orbits the Earth once every 27 days, 7 hours, and 43 minutes. It takes the same length of time to rotate once on its own axis. Orbiting speed: 2300 mph Distance from the Earth: The distance varies from 221,456-238,857 miles. Circumference of the Moon: 6,790 miles around the middle.
The exact time it takes for the Earth to make one complete orbit of the Sun is 365 days, 6 hours, 9 minutes and 10 seconds.
A leap year:
The Earth is one of nine planets that make up the Solar System.
Because it is more convenient to use a calendar of 365 whole days, every four years we have to add up the extra 6 hours, 9 minutes and 10 seconds to make an extra day. These 366-day years are called leap years.
As the Earth orbits the Sun it also rotates, or spins around. One complete rotation takes 23 hours, 56 minutes and 4 seconds. We round this period up to 24 hours and call it a day.
PLANET EARTH FROM SPACE
INSIDE PLANET EARTH
HOT AND COLD PLANET
As the Earth spins, some parts of the world are in sunlight while others are in darkness. That is why it is a different time in various places in the world. Therefore, the world has been divided up into 24 time zones. Because the Earth rotates through 360 degrees every 24 hours, each time zone covers 15 degrees of longitude on a map of the world. The zero point of longitude is at Greenwich in London. It is known as the Greenwich meridian. As you move east or west from Greenwich through each new time zone, you add or subtract an hour of time.
As Earth spins, it also tilts,
so its position in relation to
the Sun gradually changes
throughout the year.
When the northern hemisphere
is tilted toward the Sun, countries
in the north have summer.
Countries in the southern
hemisphere have winter.
SUMMER AND WINTER