Mars - eGurukul

cockedhatpocketInternet και Εφαρμογές Web

11 Δεκ 2013 (πριν από 3 χρόνια και 7 μήνες)

78 εμφανίσεις

THE UNIVERSE

9
th

Grade


Physics

9th
-

Physics

INTRODUCTION


What

do
you

see

in the
sky
?


What

comprises of the
solar

system?


The Sun


The Moon


T
he
planets



Mercury


Venus


Mars


Jupiter


Saturn


Fainter

planets


Uranus


Neptune


Asteroids


Ancients

observed


Positions of
celestial

bodies


Attempted

to
describe

the motion of
celestial

bodies


9
th

-

Physics

Constellations


Ancients

grouped

stars

into

patterns


Named

the

patterns

based

on

the

imagined

familiar

objects

and

mythical

characters


By

Ptolmey’s

time

48

constellations

have

been

known
.


By

Gallileo

Gallilei’s

time

60

constellations

were

known
.


Today

the

sky

is

divided

into

88

constellations


Of

these

the

12

constellations

lying

in

the

ecliptic

are

the

zodiacal

constellations


Constellations

were

used

to

define

the

positions

of

celestial

objects


Motion

of

planets

is

confined

to

a

narrow

belt

of

the

zodiacal

constellations


Planetary

motion

is

along

the

ecliptic

plane
.

9th
-

Physics

Constellations


Observing

Moon

and

planets

over

a

period

of

one

week

night

after

night,

Moon

displaced

more

towards

East
.

When

the

planets

do

not

even

seem

to

shift

at

all
.


This

is

because

Moon

is

very

near

to

us,

when

compared

to

planets
.


Similar

effect

is

seen

when

we

observe

an

aero

plane

flying

high
.

Aero

plane

appears

to

fly

slower

when

compared

to

the

birds
.


The

nearer

planets

like

Mercury

and

Venus

show

greater

displacement

than

the

farther

planets

Jupiter

and

Saturn
.


On

the

New

moon

day,

Moon

sets

at

the

same

time

as

the

Sun,

15

days

later

Moon

rises

in

the

East,

while

the

sun

sets

in

the

West
.


All

these

facts

can

be

drawn

by

studying

the

positions

against

the

backdrop

of

zodiacal

constellations
.



9th
-

Physics

Constellations


Constellations

served

as

a

fixed

background

against

which

the

motion

of

the

planets

can

be

observed
.


Mars

is

in

the

constellation

of

scorpius

or

in

Saggitarius


indicates

that

Mars

is

in

the

direction

of

the

particular

constellation


Mars

is

just

located

in

that

direction


Planets

are

more

nearer

to

Earth

when

compared

to

the

distance

of

the

stars

of

the

constellations


Moon,

Mars

and

rest

of

the

planets

move

in

the

eastward

direction
.

This

eastward

direction

is

called

Direct

Motion
.


Direct

motion

of

Earth

is

due

to

the

rotation

of

the

Earth
.


One

can

infer

the

motion

as

well

as

the

direction

of

motion

of

celestial

bodies,

with

the

aid

of

constellations
.


9th
-

Physics

Models

of

Solar

system


Early

Greek

astronomers

assumed

that

each

planet

went

around

the

Earth

in

a

small

circle

called

Epicycle
.

The

centre

of

the

Epicycle

also

followed

a

circular

path

around

the

fixed

Earth


The

model

in

which

Earth

remained

fixed,

and

all

the

celestial

bodies

revolved

around

it

is

called

Geocentric

model

of

Ptolemy


Planets

Mercury

and

Venus

are

not

visible

throughout

the

night
.

Mercury

can

be

seen

for

a

maximum

duration

of

two

hours
.

Venus

can

be

seen

for

about

three

hours
.


Geocentric

theory

explained

this

phenomenon

by

assuming

that

the

planets

Mercury

and

Venus

went

around

the

Earth

in

an

orbit

less

than

that

of

the

Sun
.




9th
-

Physics

Helio

Centric

Theory


Nicholas

Copernicus

(
1473
-
1543
)

proposed

a

model

in

which

the

Sun

was

at

the

Centre

while

all

the

planets

including

the

Earth

moved

around

it
.


This

theory

is

called

Helio
-
centric

(sun

centred
)

theory
.


Whatever

motion

that

appears

in

the

sky

is

due

to

the

motion

of

the

Earth

itself
.


Heliocentric

theory

easily

explained

why

Mercury

and

Venus

did

not

appear

throughout

the

night
.




9
th

-

Physics

Distance

Measurement

-

AU


When

Mercury

is

at

the

largest

separation

from

Sun,

it

makes

28


ͦ

between

the

lines

joining

the

Sun
-
Earth

and

Sun
-
Mercury
.


Sun
-
Mercury

can

be

expressed

in

terms

of

Sun
-
Earth

distance

called

Astronomical

Unit(AU)
.


1
AU

~

150

Million

Km
.


AU

is

often

employed

as

the

basic

unit

of

distance

among

solar

system

objects


Deductions

of

Copernicus

on

distance

measurement

match

very

well

with

the

current

calculations
.


Distance

measurement

is

one

of

the

key

contributions

of

Helio

centric

theory
.



9th
-

Physics

Planet

Distance

Copernican

Modern

Mercury

0.39

0.39

Venus

0.72

0.72

Earth

1.00

1.00

Mars

1.52

1.52

Jupiter

5.22

5.20

Saturn

9.07

9.54

Laws

of

Planetary

Motion


Johannes

kepler

(
1571
-
1630
)

perfected

the

Heliocentric

theory

and

described

the

motion

as

well

as

orbit

of

planets
.


The

orbit

of

Mars

was

unusually

difficult
.



Kepler

used

the

accurate

observations

of

the

positions

made

by

Tyco

Brahe
.


Kepler

studied

the

motion

of

planets

and

stated

three

laws

known

as

Kepler’s

laws

of

planetary

motion
.


First

law

states

that

the

orbit

of

planets

are

elliptical
.


Second

law

refers

to

the

period

of

the

planet
.


Third

law

refers

to

the

speed

of

the

planet

at

different

positions
.




9th
-

Physics

Mercury


Not

much

was

known

about

Mercury

until

space

probes

were

launched

in

1974


Mercury

is

small

in

size

and

is

very

close

to

the

sun


Its

surface

temperature

varies

greatly


It

sets

within

two

hours

of

the

sun

setting

or

rises

within

two

hours

of

the

sun

rising
.


Like

Earth,

Mercury

has

a

rocky

surface


It

has

no

atmosphere


A

striking

feature

of

the

planet

Mercury

is

craters


Mercury

revolves

fastest

around

the

Earth


By

the

time

Sun

moves

from

one

high

noon

position

to

the

next

with

respect

to

Mercury,

six

months

would

have

elapsed

on

the

Earth

9th
-

Physics

Venus


Venus

is

the

brightest

object

in

the

sky

next

to

the

Moon


Its

orbit

is

twice

as

large

as

Mercury’s
.


The

planet

is

visible

for

a

longer

time

than

Mercury



as

much

as

three

hours
.


Venus

and

the

Earth

have

almost

the

same

size

and

mass
.


Temperature

on

Venus

remains

a

constant

at

750
K
.


A

thick

atmosphere

of

Carbon
-
di
-
oxide

along

with

the

Sulphuric

acid

vapour

envelopes

the

planet


This

produces

enormous

pressure

at

the

surface

about

90

times

on

the

surface

of

the

Earth


The

thick

cloud

reflects

nearly

75
%

of

the

light

falling

on

it
.


This

is

the

cause

of

brightness

of

Venus

9
th

-

Physics

Green house
effect:

Carbon di oxide is opaque to heat. That is all the
heat generated within the planet is trapped. This
causes the temperature of Venus to steadily
increase.
This phenomenon is known as Green
house effect. A warning for what is in store for us
if global warming continues.


Mars


Mars

lies

in

an

orbit

larger

than

the

Earth


Seen

all

through

the

night

as

a

brilliant

red

object
.


The

axis

of

rotation

is

inclined

at

an

angle

of

about

24


to

its

orbit
.


It

experiences

Seasons

as

Earth

does
.


It

has

a

very

thin

atmosphere

mostly

composed

of

Carbon
-
di
-
oxide


It

has

two

tiny

moons

called

Phobos
,


meaning

fear

and

Deimos

meaning

panic,

that

swiftly

around

Mars
.


9th
-

Physics

Asteroids



Region

between

the

orbits

of

Mars

and

Jupiter

is

composed

of

planetsimals

that

did

not

combine

to

form

larger

bodies

like

planets
.


They

are

small

chunks

of

rocks

and

metal

that

orbit

the

Sun
.


Largest

asteroid

is

known

as

Ceres

which

has

a

diameter

of

about

950

km
.


Asteroids

are

found

to

be

between

2

and

3
.
5

AU

from

the

Sun
.


This

region

is

called

Asteroid

belt
.



9th
-

Physics

Jupiter


Most

massive

Gaseous

planet

with

a

mass

equal

to

that

of

318

Earths


The

volume

is

nearly

1400

times

that

of

the

Earth’s
.


It

accounts

for

2
/
3

rds

of

all

material

outside

the

Sun

in

the

solar

system
.


Inspite

of

huge

mass

and

volume,

it

rotates

fastest

among

all

the

planets
.


Jupiter

is

chiefly

composed

of

Helium

and

Hydrogen

gases,



Conditions

in

the

interior

of

Jupiter

make

it

less

likely

to

harbour

life
.


The

inner

temperature

may

be

13000
K

and

35000
K
.


The

pressure

is

million

times

that

on

the

Earth


Gallileo

discovered

4

moons

of

Jupiter



Lo,

Callisto
,

Ganymede

and

Europa
.

Called

as

Gallilean

Satellites
.


Gallilean

satellites

are

the

first

celestial

objects

discovered

through

telescope
.


9th
-

Physics

Saturn


Known

for

its

beautiful

rings


Huge

Gaseous

planet


Mainly

made

up

of

Hydrogen

and

Helium


Its

atmosphere

is

mostly

made

up

of

Methane,

ammonia

and

water

vapour


Density

of

Saturn

is

less

than

that

of

water


Since

the

planet

is

far

away

from

the

sun,

it

is

very

cold


Saturn’s

rings

are

composed

of

small,

unconnected

pieces

of

rock

and

dust
.


This

nature

of

rings

was

predicted

four

decades

before

it

was

discovered
.

9
th
-

Physics

The rings are tilted at an angle to
the orbit of
saturn
. The orientation,
therefore appears to change as
seen from the Earth over one
revolution of Saturn.

Uranus


First

planet

invisible

to

naked

eye

and

first

planet

to

be

discovered

by

telescope
.


Discovered

by

William

Herschel

in

1781


Doubled

the

range

of

known

solar

system,

Saturn

is

at

the

same

distance

from

Sun

as

Uranus

is

from

Saturn
.


It

receives

only

1
/
400
th

of

the

solar

energy

we

receive

on

the

Earth,

But

Its

temperature

is

not

very

low
.


Spacecraft

Voyager

does

not

reveal

any

evidence

of

life
.


By

19
th

century,

astronomers

could

precisely

predict

the

position

of

Uranus



This

prediction

was

possible

through

Kepler’s

laws

of

motion

along

with

Newton’s

law

of

Gravitation
.



The

laws

are

applicable

well

beyond

the

Earth

,

they

are

truly

universal

laws
.


9th
-

Physics

Rings of Uranus was
discovered by Prof.
J.C

Bhattacharya and
Kuppusamy

of Indian
Institute of Astrophysics

Neptune & Great Pluto War


Discovery

of

Neptune

was

entirely

due

to

the

application

of

Newton’s

laws

of

motion

and

gravitation
.


The

fact

that

the

laws

govern

the

motion

of

bodies

on

the

Earth

could

be

extended

to

motion

of

bodies

elsewhere

in

the

solar

system

is

a

big

leap

in

understanding

the

universe
.


Methane

and

Ammonia

form

the

bulk

of

Neptune’s

composition
.


This

is

another

very

cold

planet
.



9
th
-

Physics

From the time of its discovery from 1930 until 2006, Pluto was considered as the ninth planet.
Many objects similar to Pluto were discovered in the outer parts of solar system in late 20th and
21st centuries. The scattered disc like Eris is 20% more massive than Pluto. On August 24, 2006,
the
IAU

defined planet for the first time. This definition excluded Pluto from
planet hood
and
reclassified it under the new category of dwarf planet along with Eris and Ceres.


Comets


Comets

are

chiefly

composed

of

water,

carbon

monoxide,

carbon

di

oxide,

methane,

ammonia

and

hydrogen

cyanide

all

in

frozen

state


When

comets

are

well

beyond

the

orbit

of

Jupiter,

they

are

visible

as

dim

objects

only

through

powerful

telescopes
.


As

they

come

closer

to

Sun,

they

grow

brighter
.

All

comets

do

not

become

bright

enough

to

be

visible

to

naked

eyes
.

Some

comets

like

Comet

Halley

is

very

bright
.


As

comets

approach

Sun,

their

frozen

gases

gradually

vaporize
.

The

energetic

particles

produced

by

the

Sun,

pushes

the

gas

away

from

the

Sun,

leading

to

the

formation

of

tail
.


The

length

of

the

tail

increases

as

the

comet

approaches

the

sun
.

And

decreases

as

the

comet

goes

away

from

the

sun
.


The

amount

of

Sun’s

heat

reaching

the

comet

as

well

as

the

mass

of

the

gaseous

material

in

it

decide

the

length

of

the

tail
.


Kepler’s

laws

are

used

to

predict

the

positions

of

a

comet

during

its

journey
.

Using

this

it

can

even

be

concluded

that

the

comet

is

being

observed

for

the

first

time

or

it

had

been

observed

in

the

past
.



9th
-

Physics

Planetary data

9th
-

Physics

Planet

Mean

dist

(AU)

Diameter

(m)

Mass

(Kg)

Range of
Surface
Temp(K)

Mercury

0.39

4.8

x10
6


3.3

x10
23


100 to 623

Venus

0.72

1.21

x10
7

4.9

x10
24

750

Earth

1.00

1.27

x10
7

6

x10
24

183 x 333

Mars

1.52

6.8

x10
6

6.4

x10
23

133 to

293

Jupiter

5.20

1.43

x10
8

1.9

x10
27

163

Saturn

9.54

1.2

x10
8

5.9

x10
26

93

Uranus

19.19

5

x10
7

8.7

x10
25

57

Neptune

30.06

4.9

x10
7

1

x10
26

57

Structure

of Earth

The earth’s structure is classified as
below



Crust


Mantle


Core


Outer Core


Inner core



Structure

of

Earth

-

Crust


The part of earth where we stand is
called
Crust


It is about
30
-
40 km in thickness

and is the outermost layer


It is composed of rocks and is also
known as
Lithosphere


(
Lithos

means rocks)


The
rocks

are made of chemical
compounds such

as oxygen and
silicon


It contains needed nutrients for the
growth and development of plants


The crust provides food and shelter
to thousands of organism like
earthworm, ants, termites..


Finally as you know,
it holds up lot
of water

that comes down as rain
which is important as far as life on
earth is concerned



Al


Aluminum

Fe


Iron

Ca



Calcium

Na


Sodium

Mg


Magnesium

K


Potassium

T


Titanium

H
-

Hydrogen

Structure of Earth
-

Mantle



Mantle is the portion of the earth
below the crust


It is about
2900 km in thickness


It is composed of
silicates of iron
and magnesium


As crust is not deep, study of
features like composition,
temperature and pressure is
possible using measuring
instruments, while
study of mantle
needs to be done by indirect means
as it is too deep


Hence study of mantle is done by
studying the vibrations caused by
earth




Fact file



Spiders are scientists tool


Spiders weave a web and wait for
their prey


As soon as they fly gets stuck, the
spider feels the vibrations


The vibrations reach the
s
pider from
various directions


Spider analyzes the strength of
vibration to find the position and
possibly the size of prey


Hence, vibrations can be used to
detect objects and also to infer the
nature of the object


The same principle is used by
humans to understand the mantle
through earth quake vibrations





Structure of

Earth

-

Core



Core is the portion of the earth below
the mantle


Its
radius is about 3470 km
, about half
the size of earth


Temperature

of core is about
4000
kelvin

while the pressure is very high


Magnetic compass always aligns in
north
-
south direction


any idea why is
it so?


Until 1600 AD this was believed to be
caused by a pole star, but Sir William
Gilbert explained that the alignment
was due to earth behaving as giant
magnetic field


Now, how does the earth behave as
giant magnetic field?


The magnetic field is due to the
motion of molten iron at the core and
this motion is caused by
-



Rotation of the earth as well as the
convection currents due to heat of
molten iron




Atmosphere



Atmosphere stretches of about few
hundred kilometers. For living process,
up to a height 50 km is essential


Atmosphere composition:


Major components includes
nitrogen
and oxygen


Nitrogen is key ingredient of amino
acids


Nitrogen is also essential for plants


But, plants cannot take nitrogen
directly, so


Bacteria on earths crust helps plants
to take nitrogen. They are known as
nitrogen
-
fixing bacteria


Water vapor

in the atmosphere is the
third component in the atmosphere
important for weather conditions




Layers

of Atmosphere

-

Troposphere



Atmosphere is classified into
different layers based on
temperature and composition


TROPOSPHERE
(
tropos

means heat)


The layer nearest to the crust is the
troposphere


It
extends to a height of 11 km


75% of air molecules
that make up
the atmosphere are found in
troposphere


Oxygen and nitrogen

the key
elements of living organisms survival
float around in troposphere


Troposphere
is also important in
deciding the weather conditions,
i.e

fog, haze, rain…




Layers of

Atmosphere

-

Stratosphere



The layer above the troposphere is
the stratosphere


It
extends to a height of 40 km from
troposphere


It contains Ozone (an allotrope of
oxygen).


Molecule of Oxygen is made of two
atoms of oxygen but ozone contains
three atoms of oxygen (
O3
)


Concentration of ozone is very less ~
one molecule in four million


Ozone
plays an important role is
absorbing the harmful ultra
-
violet
(UV) rays present in sunlight


Life on earth survives as
Ozone
acts
as a shield from UV radiation




Layers

of
Atmosphere

-

Hydrosphere



2/3
rd

of earths surface is water


Water is the only liquid that exists in three state of matter on earth


As frozen ice caps, in ocean and as water vapor in atmosphere


Living organisms in oceans gradually increased the content of oxygen in the
atmosphere by biological process known as
photo synthesis


With the production of oxygen came ozone and hence the emergence of life on
earth


So, even hydrosphere influences the composition of the atmosphere and in turn
the life on land

Layers

of Atmosphere



Weather


(Convection

Current)



A
known fact
-

Earth receives heat and
light from Sun


Air molecules on earth gets heated up
when the come in contact with heated
land surface


Hot air is less dense than cold air


So hot air rises up and gradually gets
cooled


Meanwhile, the cold air that displaces
the hot air gets heated up


Now this heated up air rises up.


This phenomenon, where hot air rises
up and cold air coming down set up
the
convection current


Fact File


This is the same principle
seen in boiling of water


Hence, as heat energy is transported
using the air in atmosphere, the
atmosphere acts as a
heat distribution
system

Layers

of Atmosphere



Weather

(Water

Cycle)



Water in the earth also plays an
important role in heat energy distribution


As we already know, water covers 2/3
rd

of earths surface


Water in lakes, seas and ocean vaporize
slowly due to the sun’s heat


But, as water has a high specific heat,
hence, lot of heat energy is needed for
water to vaporize


The water vapor that rises in the
atmosphere, stays there in the
atmosphere and forms clouds with dust
particles


When the clouds condense and cool,
water vapor changes to liquid form and
comes down as
rain. This is how we get
rainfall on earth


This phenomenon is called the Water
Cylce


The processes Convection Current and
the Water cycle ensures pleasant
weather conditions on earth

Layers

of Atmosphere



Weather




The processes Convection Current and the Water cycle help matter to move in
vertical direction only


This would not be much help in distributing heat energy across the globe


The earths rotation ensures that the moving air is deflected from its vertical path


As the air rises up vertically, it is subjected to a sideward force due to earths rotation


Hence, the air rises up and moves side wards resulting in distribution of heat energy
over larger surface area of the earth

Fact

File

-

Water



Water is a wonderful and much needed compound to sustain life on earth


Nearly
70% of the cell is water


Water dissolves a number of compounds like Carbon di
-
oxide and oxygen and salts in the
body


Water is essential for blood circulation


Force of attraction among molecules of water aids capillary action, this helps plants to
reach leaves


Carbon di
-
oxide and water combine to produce carbohydrate


As water freezes, its volume increases, and because of this ice floats on water


This unique property helps the cells on seas and oceans to survive


Earth as a

dynamic

system


Earth

appears

static,

But

the

truth

is

that

Earth

is

working

actively

all

the

time
.



It

receives

energy

from

the

Sun,

drives

convection

current

in

the

atmosphere,

sets

up

water

cycle

process

all

the

time
.


It

rotates

continuously

and

distributes

the

water

and

air

molecules

and

energy

all

over

the

planet
.


Earth

is

very

much

like

a

living

system
.


A

living

system

has

several

individual

parts
.

The

individual

parts

cannot

exclusively

constitute

a

system
.


The

basic

factor

is

co
-
ordination
.


Earth

co
-
ordinates

among

all

its

individual

components

-

living

as

well

as

non
-
living
.



9th
-

Physics