Transcript Threats to Earth - World of Teaching

Threats to Earth
P2g part 1 & 2
Objectives
In this lesson we should learn:
• about the properties of asteroids
• how asteroids have affected Earth in the
past
Outcomes
Foundation Paper
You should now be able to..
• State that large asteroids have collided with the
Earth in the past and describe some of the
consequences and evidence of such collisions
• State that asteroids are rocks and describe that
asteroids are left over from the formation of the
Solar System and where they can be found.
Higher paper
• Explain why the asteroid belt is between Mars
and Jupiter: the large gravity of Jupiter disrupts
the formation of a planet
The asteroid
Gaspra, found
in the Asteroid
Belt between
Mars & Jupiter
Asteroid Ida with it’s moon
Dactyl
Asteroids
• Asteroids are large rocks left over from the formation of
the Solar System
They are mostly between the orbits of Mars and Jupiter
• Asteroids (large rocks) have collided
with the Earth in the past causing:
- craters,
- ejection of hot rocks,
- widespread fires,
- sunlight blocked by dust,
- climate change,
- species extinction
Collisions?
• The evidence for past collision on Earth
includes:
- craters
- layers of unusual elements in rocks
- sudden changes of fossil numbers
between adjacent layers of rock.
Rocks
Asteroids are small ______________
which orbit the
Sun
Mars
______________,
mainly between ______________
and
Jupiter
______________.
Occasionally, a long time ago,
______________
Asteroids are thought to have struck
craters
______________,
forming large ______________
and huge
Earth
water
amounts of ______________
and ______________
vapour.
dust
An enormous asteroid is believed to have hit
Earth
______________
65 ______________
years ago, leading to
million
the ______________
of the ______________.
extinction
dinosaurs
______________
could not penetrate the ______________
sunlight
atmosphere
temperatures fell, causing ______________
climate
so ______________
change.
Asteroids
craters
extinction
million
snowballs
water
atmosphere
dinosaurs
Jupiter
Neptune
Sun
climate
dust
Mars
rocks
sunlight
comets
Earth
meteors
Saturn
temperatures
Outcomes
Foundation Paper
You should now be able to..
State that large asteroids have collided with the
Earth in the past and describe some of the
consequences and evidence of such collisions
State that asteroids are rocks and describe that
asteroids are left over from the formation of the
Solar System and where they can be found.
Higher paper
Explain why the asteroid belt is between Mars
and Jupiter: the large gravity of Jupiter disrupts
the formation of a planet
Objectives
• In this lesson we should learn:
• about the properties of comets
• how astronomers are monitoring the
danger from near-Earth asteroids and
comets
Outcomes
Foundation Paper
You should now be able to..
• Describe that a comet is made from ice and dust, the tail
of a is a trail of debris and that comets have highly
elliptical orbits
• Describe that the speed of a comet increases as it
approaches a star
• Describe a near-Earth object (NEO) as an asteroid or
comet on a possible collision course with Earth and how
NEO may be seen with telescopes and that observations
can be used to determine their trajectories
Higher paper
• Explain why the speed of a comet increases as it
approaches a star: the strength of gravity increases
• Suggest and discuss possible actions which could be
taken to reduce the threat of NEOs
Halley’s Comet
Reappears every 76 years
Image from 1986
Hale-Bopp as seen from
Craig County, VA in 1997
Hale-Bopp
as seen
from
Alexandria,
VA in 1997
Hale-Bopp as seen from
Wyoming in 1997
Yerkes
Observatory
Comets
• Comets are balls of rock and ice, with trails of
debris blown outward by the Sun
• They have highly elliptical orbits and speed up
as they approach the sun
• The trajectories of observed objects
can be predicted accurately
• If an asteroid (or comet) on a collision course
with Earth is spotted early enough, it may be
possible to alter the trajectory of the asteroid
Threats to Earth
1. How can asteroids and comets be seen?
2. What is the difference between a comet
and an asteroid?
3. What can be done to protect us from
asteroid impacts?
Threats to Earth
Answers
1. How can asteroids and comets be seen?
With telescopes,
because they reflect light from the Sun.
2. What is the difference between a comet
and an asteroid?
Asteroids are large rocks usually in orbit
between Mars and Jupiter. Comets are ice
and rock found in very elliptical orbits.
3. What can be done to protect us from
asteroid impacts?
Detect them early
and then alter their course.
Outcomes
Foundation Paper
You should now be able to..
Describe that a comet is made from ice and dust, the tail
of a is a trail of debris and that comets have highly
elliptical orbits
Describe that the speed of a comet increases as it
approaches a star
Describe a near-Earth object (NEO) as an asteroid or
comet on a possible collision course with Earth and how
NEO may be seen with telescopes and that observations
can be used to determine their trajectories
Higher paper
Explain why the speed of a comet increases as it
approaches a star: the strength of gravity increases
Suggest and discuss possible actions which could be
taken to reduce the threat of NEOs
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