1) Comets, asteroids, and meteoroids are remnants from the formation of the solar system. Comets originate from the Oort Cloud or Kuiper Belt, while asteroids originate from the Main Asteroid Belt. 2) When meteoroids enter Earth's atmosphere, they heat up and glow, appearing as meteors or "shooting stars." Any fragments that reach the ground are called meteorites. Meteor showers occur when Earth passes through the orbit of a comet. 3) Earth has been hit by comets and asteroids in the past, with major impacts potentially causing mass extinctions. Small impacts from meteoroids are more frequent but less damaging. Large impacts capable of threatening life on Earth occur on time

1. COMETS, ASTEROIDS
AND METEORS
SCIENCE 8

2. Learning Objectives:
•Compare and contrast the comets, meteors,
and asteroids.
•Predict the appearance of comets based on
recorded data of previous.
•Explain the occurrence of meteor shower.

3. •Recent advances in space technology have
allowed scientists coming from different
background such as physics, chemistry,
biology, and geology to collaborate on
studying Near-Earth Objects (NEO) such as
comets and asteroids.

4. •With more powerful telescopes and space
probes, the study of comets and asteroids
provides more clues about the origins of our
solar system.

5. •Amateur and professional astronomers have
discovered several NEOs that came close to
Earth, the most recent asteroid being
Asteroid 2012 DA14.
•It made a very close approach to Earth as it
orbited the Sun on February 16, 2012
(Philippine Time).

6. •In the morning of the same day, an asteroid
entered Earth’s atmosphere and exploded
over Lake Chebarkul in Russia hurting about
1,000 people in the process.
•These two events triggered superstitions,
fears, and doomsday prophecies held by
different cultures.

7. •But do these things have scientific basis?

8. •Has Earth ever been hit by a comet or an
asteroid?
•If yes, how have such impacts affected
Earth?
•How often does a comet or an asteroid hit
Earth?

9. ACTIVITY
What happens when a comet or
an asteroid hits Earth?

10. •Comets and asteroids are referred to by
astronomers as Near-Earth Objects (NEO).
•Comets are icy bodies or objects while
asteroids are rocky fragments.
•They are remnants from the formation of
our solar system 4.6 billion years ago.

12. Shape
•Varied/ irregular

13. Size
1-100 ++ 1-10 (nucleus only)

14. Chemical Composition

15. •Asteroid and Comet both reflect light from
the Sun in varying amounts depending on
the size and composition.
•The presence of more silicates allows a
comet or asteroid to reflect light.

16. •Comets and asteroids both orbit the Sun
and move relatively slow when viewed from
Earth.

17. •Comets usually come from the Oort Cloud
which is beyond our Solar System, and a few
from Kuiper Belt which is just beyond
Neptune’s orbit.

18. •Long-period comets come from the Oort
Cloud, while short-period comets come
from the Kuiper Belt.

19. •Comet Halley, the most famous comet of
157 the 20th century is the only known
short-period comet.
•It takes 75-79 years for Comet Halley to
orbit the Sun

22. •Asteroids originate from the Main Asteroid
Belt between Mars and Jupiter.
•This belt is theorized by scientists to be
remnants of a planet that did not
completely form.

25. •The orbit of an asteroid is more rounded
and less elliptical than the orbit of a comet.

27. •In February 2013, Asteroid 2012 DA14 made
a very close approach to Earth as it orbited
the Sun.
•Distance in space is measured in light years
and this Asteroid was just 0.4 light year
away from Earth, the closest that any
asteroid has ever been to Earth.

29. Meteoroid, Meteor and Meteorite
•What is a METEOR?
also known as shooting star.
It is not a star.
It is a light phenomenon or a streak of light
that occurs when a meteoroid burns up as it
enters Earth’s atmosphere.

30. Meteoroid, Meteor and Meteorite
•What is a METEOROID?
broken up rock and dust
Came from celestial bodies like comet,
asteroid, the Moon, or from Mars.
can be as small as a grain of sand or as big as
a boulder

31. Meteoroid, Meteor and Meteorite
•What is a METEOROID?
When it enters Earth’s atmosphere, the air in
front of the meteoroid heats up, causing
materials to burn up.
these glowing materials appear as a streak of
light or a fast-moving bright object that
appears to have a tail just like a comet.

32. Meteoroid, Meteor and Meteorite
•What is a METEOROID?
usually all burns up when it enters Earth’s
atmosphere.

33. Meteoroid, Meteor and Meteorite
•What is a METEORITE?
when a fragment from the meteoroid
survives and makes it to the ground, this space
rock fragment is the meteorite.

34. Meteoroid, Meteor and Meteorite
•What is a METEOR SHOWER?
Comets orbit the Sun and leave fragments
along their orbit as they continue their
journey around the Sun. These fragments
continue to orbit the Sun just like their parent
comets.

35. Meteoroid, Meteor and Meteorite
•What is a METEOR SHOWER?
When Earth orbits the Sun and passes
through the orbit of a comet where these
comet fragments are found, we observe many
streaks of light from Earth which is called a
meteor shower.

36. Meteoroid, Meteor and Meteorite
•What is a METEOR SHOWER?
During a meteor shower, meteors seem to
originate from only one point in the sky
because the meteoroids are traveling in
parallel paths with the same velocity.

37. Meteoroid, Meteor and Meteorite
•What is a METEOR SHOWER?
The meteor shower is named after the
constellation where they seem to originate
from, but this does not mean that the
meteoroids come from the associated
constellation.

39. •Has Earth ever been hit by a comet or an
asteroid?
•If yes, how have such impacts affected
Earth?
•How often does a comet or an asteroid hit
Earth?