Earth EARTH by techlove


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Earth is one the nine Planets in Milky way Galaxy.


Earth spins like a top on its axis. Earth’s axis is an imaginary line that goes through Earth
from the North Pole to the South Pole. Earth’s axis is slightly tipped, like a spinning top
leaning to one side.

Earth travels around the Sun at about 67,000 miles per hour (about 107,000 kilometers
per hour). One year is one trip around the Sun. Earth’s path around the Sun is slightly
oval-shaped. This oval shape causes Earth’s distance from the Sun to change during the


The Sun seems to rise in the morning, cross the sky during the day, and set at night.
However, the Sun does not actually move around Earth. Earth’s turning on its axis makes
it look as if the Sun is moving.

Earth makes a complete turn on its axis every 24 hours. As Earth turns, half of the planet
faces the Sun, and the other half faces away. It is daytime on the half facing the Sun. It is
night on the half facing away from the Sun.


Earth has seasons because of the tilt of its axis. For part of the year, the top half of Earth
is tipped toward the Sun. The top half of Earth is called the Northern Hemisphere. During
another part of the year, the bottom half of Earth is tipped toward the Sun. The bottom
half is called the Southern Hemisphere. It is summer in the half that is tipped toward the
Sun. It is winter in the half tipped away. When it is summer in the Northern Hemisphere,
it is winter in the Southern Hemisphere. During spring and fall the hemispheres are
tipped neither toward nor away from the Sun.

The equator is an imaginary line around Earth’s middle. The farther you are from the
equator, the greater the difference in temperature between seasons. The equator never tips
far from the Sun. Near the equator it is warm enough to go swimming all year long. The
average temperature barely changes from month to month. In Alaska, far from the
equator, the average temperature in January can be more than 60 degrees colder than it is
in July.


Earth is made of layers. The top layer is called the crust. It is made of hard rock and soil.
More than 70 percent of Earth’s crust is covered with water. Most of the water is salt
water in the ocean. Pieces of dry land called continents rise above the ocean. The part of
Earth’s crust under the ocean is called the seafloor.

Under the crust is a layer of partly melted rock called the mantle. Under the mantle is
Earth’s core. The core is mostly iron. The outer part of the core is liquid metal. The inside
of the core is solid metal. Scientists believe that the liquid metal makes Earth a giant
magnet and creates Earth’s magnetic field.

Earth’s crust is made of gigantic slabs of rock called plates that move over the mantle.
Plates crash together to make mountains. They pull apart and let red-hot rock ooze up
from inside Earth to make new crust.


Scientists think that Earth and the rest of the solar system formed from a spinning cloud
of gas and dust. Gravity pulled most of the gas and dust together to form the Sun. Some
leftover gas and dust formed Earth and the other planets. Scientists think that Earth and
the Moon formed about 4.6 billion years ago.

The Milky Way Galaxy belongs to a cluster of about 30 galaxies called the Local Group.
Within the Local Group, the Andromeda Galaxy is the galaxy closest to the Milky
Way. The Andromeda Galaxy is so far from Earth that it takes about two million years
for its light to reach us from there.
The Sun joins about 400 billion other stars to form a galaxy called the Milky Way. The
Milky Way Galaxy is shaped like a pinwheel, with curved arms that circle around the
center. The Sun and solar system are located in one of the pinwheel’s arms out toward the
edge of the galaxy.
After the Sun, the closest star to Earth is Proxima Centauri, more than 20 trillion miles
(30 trillion kilometers) away. While light from the Sun takes only about eight minutes to
reach Earth, other stars are so distant that their light takes billions of years to reach Earth.
Earth is one of nine planets that circle around the Sun to form a solar system. The Sun’s
gravity is so powerful that it can hold objects in orbit that are billions of miles away.

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