Earth is a planet that formed around 4.6 billion years ago from a cloud of gas and dust. It is the only planet known to support life. Earth is spherical in shape but slightly oblate, meaning it bulges at the equator. It rotates on its axis once every 24 hours and revolves around the sun once every 365 days. Earth has four major interior layers - crust, mantle, outer core, and inner core. NASA studies Earth using satellites to monitor changes to its land, oceans, atmosphere, and climate in order to better understand and predict environmental changes.

1. THE PLANET EARTH

2. EARTH
 Earth is the only planet to be
named in English. The word
‘Earth’ is Old English word for
“land“
 Earth belongs to the Milky Way
Galaxy
 Earth is the only planet to
sustain life

3. SHAPE OF THE EARTH
 The study of size and shape of earth is called
geodesy.
 Before 500 BC, people thought that earth was
flat. But thanks to scientists like Aristotle and
Pythagoras, people know that the shape of the
earth is spherical. However Sir Isaac Newton
showed that the earth was not a perfect sphere,
but a compressed spheroid.

4. SHAPE OF THE EARTH
 The true shape of the Earth is
called an Oblate Spheroid. – The
term "Oblate" refers to its
slightly oblong appearance. –
The term "Spheroid" means that
it is almost a sphere, but not
quite. – The Earths shape is only
very slightly oblate.

5. EARTH'S FORMATION AND
EVOLUTION
 Scientists think Earth was formed at roughly
the same time as the sun and other planets
some 4.6 billion years ago, when the solar
system came from a giant, rotating cloud of gas
and dust known as the solar nebula. As the
nebula collapsed because of its gravity, it spun
faster and flattened into a disk. Most of the
material was pulled toward the center to form
the sun. Other particles within the disk collided
and stuck together to form ever-larger bodies,
including Earth.

6.  Scientists think Earth started off as
a waterless mass of rock. Radioactive
materials in the rock and increasing
pressure deep within the Earth
generated enough heat to melt Earth's
interior, causing some chemicals to rise
to the surface and form water, while
others became the gases of the
atmosphere. Recent evidence suggests
that Earth's crust and oceans may have
formed within about 200 million years
after the planet had taken shape.
EARTH'S FORMATION AND
EVOLUTION

7.  The history of Earth is divided into
four eons — starting with the
earliest, these are the Hadean,
Archean, Proterozoic and
Phanerozoic. The first three eons,
which together lasted nearly 4
billion years, are together known as
the Precambrian. Evidence for life
has been found in the Archaean
about 3.8 billion years ago, but life
did not become abundant until the
Phanerozoic.
EARTH'S FORMATION AND
EVOLUTION

8.  The Phanerozoic is divided into three eras —
starting with the earliest, these are the
Paleozoic, Mesozoic, and Cenozoic.
 The Paleozoic Era saw the development of
many kinds of animals and plants in the seas
and on land.
 The Mesozoic Era was the age of dinosaurs
 The Cenozoic Era we are in currently is the age
of mammals.
EARTH'S FORMATION AND
EVOLUTION

11. STRUCTURE OF THE
EARTH’S INTERIOR
The structure of earth (also
referred as cross–section) is
divided into mainly four
layers namely Crust, Mantle,
Inner Core and Outer Core .

12.  Outermost layer of the Earth. It is also
the surface of the Earth.
 This comprises the continents and ocean
basins and therefore it has been classified
into continental crust and oceanic crust.
 Continental crust averages some 25 miles
(40 km) thick, although it can be thinner
or thicker in some areas. Oceanic crust is
usually only about 5 miles (8 km) thick.
CRUST

13.  About 1,800 miles (2,900 km) thick.
 Earth's crust floats on the mantle much as
a wood floats on water, and the slow
motion of rock in the mantle shuffles
continents around and causes
earthquakes, volcanoes, and the
formation of mountain ranges.
 The division between the crust and the
mantle is called the Mohorovicic
discontinuity, or simply the Moho.
MANTLE

14.  Earth's core is about 4,400 miles (7,100
km) wide
 Outer core- hot and liquid layer
comprising mainly of Nickel and Iron
(liquid).
 The transition space between outer core
and mantle is called Gutenberg
discontinuity
CORE

15.  Inner core- mostly made of solid iron and
has little amounts of nickel.
 believed to have the extreme
temperature and pressure conditions.
 The transition region between outer core
and inner core is called Lehmann
discontinuity
CORE

16. ORBITAL
CHARACTERISTICS
 Earth spins on an imaginary line
called an axis that runs from the
North Pole to the South Pole,
while also orbiting the sun. It
takes Earth 23.439 hours to
complete a rotation on its axis,
and roughly 365.26 days to
complete an orbit around the sun.

17.  Earth's orbit is not a perfect circle, but
is rather an oval-shaped ellipse, like
that of the orbits of all the other
planets.
ORBITAL
CHARACTERISTICS

18. ORBIT & ROTATION
Some statistics about Earth, according to NASA:
 Average distance from the sun: 92,956,050 miles (149,598,262 km)
 Perihelion (closest approach to the sun): 91,402,640 miles (147,098,291
km)
 Aphelion (farthest distance from the sun): 94,509,460 miles (152,098,233
km)
 Length of solar day (single rotation on its axis): 23.934 hours
 Length of year (single revolution around the sun): 365.26 days
 Equatorial inclination to orbit: 23.4393 degrees

19. MOTIONS OF THE EARTH
 Rotation- rotation of the planet Earth around its own axis
 The earth rotates on its axis from west to east or counter clockwise.
 The rotation of the earth results in the alternation of day and night.
 Areas facing toward the sun experience daytime. Areas facing away
from the sun experience nighttime.

20. MOTIONS OF THE EARTH
 Revolution- earth’s movement around
the sun
 The earth revolves or goes around the
sun in elliptical or oval orbit, from west
to east.
 It takes 365 days, 5 hours, 48 mins., and
46 seconds (365 and ¼ days).
 A year with 366 days is called a leap
year.

21.  Why Does Earth Have Seasons?
Earth has seasons because its axis is tilted.
Thus, the sun's rays hit different parts of the
planet more directly depending on the time of
year.
 Summer is warmer than winter (in each
hemisphere) because the Sun's rays hit the
Earth at a more direct angle during summer
than during winter and also because the days
are much longer than the nights during the
summer. During the winter, the Sun's rays hit
the Earth at an extreme angle, and the days
are very short. These effects are due to the
tilt of the Earth's axis.

22.  Solstices
The solstices are days when the Sun reaches its
farthest northern and southern declinations. The
winter solstice occurs on December 21 or 22 and
marks the beginning of winter (this is the shortest
day of the year). The summer solstice occurs on
June 21 and marks the beginning of summer (this is
the longest day of the year)
 Equinoxes
Equinoxes are days in which day and night are of
equal duration. The two yearly equinoxes occur
when the Sun crosses the celestial equator.The
vernal equinox occurs in late March (this is the
beginning of spring in the Northern Hemisphere and
the beginning of fall in the Southern Hemisphere);
the autumnal equinox occurs in late September
(this is the beginning of fall in the Northern
Hemisphere and the beginning of spring in the
Southern Hemisphere).

23. STANDARD TIME
 For millennia, people have measured
time based on the position of the sun; it
was noon when the sun was highest in
the sky. Sundials were used well into
the Middle Ages, at which time
mechanical clocks began to appear.
Cities would set their town clock by
measuring the position of the sun, but
every city would be on a slightly
different time.

24. PHILIPPINE STANDARD TIME
 was instituted through Batas Pambansa Blg. 8 (that defined
the metric system), approved on 2 December 1978 and implemented
on 1 January 1983. The Philippines is one of the few countries to
officially and almost exclusively use the 12-hour clock in non-
military situations.

25. LOCATING PLACES ON EARTH
 The vertical lines originating from
the north pole and end with the
south pole are called meridians of
longitude.
 Parallels of latitude are marked
horizontally on maps or globes,
starting at the equator. These
imaginary lines run east to west.

26.  Why and How Does NASA Study Earth?
NASA studies Earth to learn about how the planet changes. Earth's parts -
land, air, water and life - are always changing. Some of the changes are
natural and some are caused by humans. Scientists want to understand how
Earth has changed in the past and how it is changing now. This information
helps them predict how Earth might change in the future.
 NASA studies Earth using satellites. Satellites look toward Earth from space.
They take pictures of, and collect information about, all of Earth's parts.
NASA satellites are especially good for observing clouds, oceans, land and ice.
They also measure gases in the atmosphere, such as ozone and carbon
dioxide. They measure how much energy enters and leaves Earth's
atmosphere. And they monitor wildfires, volcanoes and their smoke.
 Information gathered by NASA satellites helps scientists predict weather and
climate. It also helps public health officials track disease and famine. It helps
farmers decide when to plant crops and what kinds to plant. And it helps
emergency workers respond to natural disasters.
 The more people know about Earth and its current and predicted changes,
the better decisions they can make.

27. AMAZINF FACTS ABOUT
THE PLANET EARTH

28.  Earth was originally born as a twin to the
planet Theia, which was about half as wide as
Earth and roughly the size of Mars. The two
planets shared an orbit for several million
years until they collided. Earth absorbed
Theia, and the remaining debris eventually
coagulated into Earth’s moon. The mass
donated by Theia gave Earth the gravity
necessary to sustain a substantial atmosphere.

29.  The world's largest desert is the Sahara, it
covers about one third of Africa!

30.  Stretching out to an impressive length of
6696 kilometres (4160 miles) long, the Nile
River is the longest river on earth.

31.  Mt. Everest is the highest mountain on
earth, its peak reaches 8,848 metres (29029
feet) above sea level.

32. Hot Spot
 The fiery award for Earth's hottest spot goes
to El Azizia, Libya, where temperature
records from weather stations reveal it hit
136 degrees Fahrenheit (57.8 degrees Celsius)
on Setp. 13, 1922, according to NASA Earth
Observatory.

33. Coldest Spot
 It may come as no surprise that the coldest place on Earth can be
found in Antarctica, but the chill factor is somewhat unbelievable.
Winter temperatures there can drop below minus 100 degrees F
(minus 73 degrees C). The lowest temperature ever recorded on Earth
came from Russia's Vostok Station, where records show the air plunged
to a bone-chilling minus 128.6 degrees F (minus 89.2 degrees C) on
July 21,1983, according to the USGS.