The document discusses the unique properties of Earth that enable life. It describes how Earth's distance from the sun, atmosphere, size and mass, magnetic field, and presence of water all contribute to regulating temperature and protecting life from radiation. The atmosphere protects living things through mechanisms like photodissociation that break down ozone into elemental oxygen, converting harmful radiation to less harmful radiation. Earth's gravity also helps maintain its atmosphere and keep the moon in orbit. Understanding Earth's unique characteristics is significant for recognizing what enables life on the planet.

1. LESSON 1: UNIQUENESS
OF THE EARTH
recognize the uniqueness of the earth being the only planet in the solar
system with properties necessary to support life (S11/12ES-la-e-3)

4. Earth’s Location
 Earth is the third planet in the
solar system.
 is considered to be one of the
inner planets next to Venus.
 Its distance from the sun is
about 93 million miles and it
takes about 500 seconds for
sunlight to reach the earth’s
surface. This distance from the
sun is enough to support life.

5. Earth’s Atmosphere
 The atmosphere is the gaseous layer
that envelops the earth. It regulates
the planet’s surface temperature.
 However, due to its cooling
mechanisms, it protects the living
things to be directly affected with
harmful radiation.
 O3 → O2 + O
 Photodissociation is the process by
which ozone molecules (O3) in the
stratosphere is broken down
(decomposition reaction) into
elemental oxygen (O) and diatomic
oxygen (O2) as it absorbs high energy
solar radiation and then convert it into
low energy radiation. This way,
harmful high-energy radiation will not
go directly into the earth’s surface.

6. Earth’s Size and Mass
 The size of the earth also plays a
vital role in keeping its life
support system afloat.
 The size of a planet is directly
related to its gravitational pull.
The acceleration due to gravity
helps the planet maintain its
atmosphere.
 Earth interacts gravitationally
with the sun. Its gravity as a
result of its mass, also keeps the
moon along its orbit.
 The moon, as the only natural
satellite of Earth, plays a vital
role in the existence of all life
forms.

7. Earth’s Magnetic Field
 Its geographic north serves
as its magnetic south and
its geographic south serves
as its magnetic north.
 The inner core is the solid
layer of the earth and is
made predominantly of
iron.

9. Presence of Water
 Life as we know it, is impossible
without a biologically essential
compound called water (H2O).
 water exists as gas forming clouds,
as liquid in the form of oceans and
lakes and as solid in the form ice
caps.
 Water has a cooling effect due to its
heat capacity. It has the capacity to
absorb heat without raising its own
temperature. As a result, life on
earth will be benefited by the
cooling effect of water.

12. 1. What is the significance of
understanding the characteristics of
the earth?
2. Which of the aforementioned unique
characteristic of earth do you like the
most and why?

13. Rubrics 1 : for Essay/ Writing
Activity
Content & Development (70 %)
Organization & Structure(15 %)
Grammar, Punctuation & Spelling (15 %)