In sky we can countless stars, some are
bright some are not so bright.
Some of them twinkle, some are not
The object that do not twinkle are planets
Moon is the brightest object in the night
Moon, stars, planets and many other
objects in the sky are called celestial
Average Distance From Earth
238,857 miles (384,403 km)
2,160 miles (3,476 km)
(about ¼ of Earth’s diameter)
1/81 of Earth’s mass
About 29 ½ Earth days
Temperature Day and Night
Day: 261º F (127º C)
Night: -279º F (-173º C)
Multiply your weight by .17
The moon is Earth‘s only natural satellite.
The moon is a cold, dry orb whose
surface is studded with craters and strewn
with rocks and dust.
The moon has no atmosphere.
Recent lunar missions indicate that there
might be some frozen ice at the poles.
The moon rises in the east and sets in the
The day on which the whole disk of the
moon is visible is known as the full moon
On the fifteenth day after full moon day
moon is not visible. This is new moon day
Next day only a small portion of the moon
is appears on the sky, known as crescent
The various shapes of the bright part of the
moon as seen during a month are called
phases of the moon
Moon does not produce its own light. We
see the moon when sun light falling on it get
reflected towards us. So we see a part of the
moon that sun light reflected towards us.
The size of the illuminated part of the moon
visible from the earth increases day by day
after new moon and vice versa after full
The moon completes one rotation on its axis
as it completes one revolution around the
The revolution of the Moon around the Earth
makes the Moon appear as if it is changing
shape in the sky. From Earth we see the Moon
grow from a thin crescent to a full disk (or full
moon) and then shrink back to a thin crescent
again before vanishing for a few days.
What causes part of the Moon to be lit up?
The moon is illuminated because it reflects
the light from the sun. The part of the moon
facing the sun is lit up. The part facing away
from the sun is in darkness.
The Moon has almost no atmosphere, because of its
weak gravity. All types of gas will escape from its
surface.Without an atmosphere, there is no wind or
The surface temperature fluctuates from roughly
+300° F during the daytime to -270 F during the
night. This is because there is not enough
atmosphere to keep the Moon warm at night, nor
protect it from the Sun's rays in the daytime.
Surface are dusty and barren
There are many craters of different size
Large number of steep and high mountains
No water in moon
On July 21, 1969 (Indian time) the American astronaut
Neil Amstrong landed on the moon for the first time.
Followed by Edwin Aldrin
On Space craft APOLLO 11
Definition : A celestial body of hot gases that radiates
energy derived from thermonuclear reactions in the
The nearest star is 4.2 LY away (40 trillion km!)
The distance to stars may be computed using parallax
or apparent brightness
Stars appear as point sources in even the most
A star’s mass may be deduced from interactions with
Most stars are about 71% hydrogen and 27% helium
Most stars have enough fuel to burn for billions of
A star’s size is estimated by mass, brightness
Most other useful information (including
composition) is acquired through
Stars appear to move from east to west
That is rises in the east and sets in the west
It is due to the rotation of earth
Stars are gigantic gravity-induced fusion
The core temperatures of all stars are millions
The Sun is just one of 100 billion stars in our
galaxy, the Milky Way.
The Sun is 93 million miles (150 million
kilometers) from Earth
Only about a billionth of the total energy
emitted by the Sun reaches Earth.
The size is about 800,000 miles (more than
million kilometers)across – more than 100
Earths could fit across the Sun's face. (Some
stars are hundreds of times wider than the
Deep in the core*, the temperature is an amazing
27 million degrees Fahrenheit (15 million degrees
The surface of the Sun is almost 11,000 degrees
Fahrenheit (6000 degrees Celsius).
The Sun's outer atmosphere (the corona*) is even
hotter – about 2 million degrees Fahrenheit
The distance between sun and earth is expressed
(1million degrees Celsius).
in ‘light years’.
One light year is the distance travelled by light in
The speed of light is about 300,000 km /s.
Light from sun take about 8 minute
to reach earth
So the distance is 8 light minutes
The distance to alpha centaury is
about 4.3 light years
pole star is a visible star, preferably a
prominent one, that is approximately aligned
with the Earth's axis of rotation; that is, a star
whose apparent position is close to one of the
celestial poles, and which lies approximately
directly overhead when viewed from the
Earth's North Pole or South Pole (we feel it is
Constellations are groups of stars
that forms a recognizable shape
constellations were named by ancient peoples.
different cultures have identified and named
The Northern Hemisphere's constellations are
named from Greek and Roman mythology.
The Southern Hemisphere's constellations are
named from instruments, objects, and animals
that explorers encountered.
The constellations were named between 14001700 A.D.
Some of the well known constellations are
Ursa Major (Big Dipper, Great Bear, Saptharshi)
We can see during summer time in the
early part of the night
Contains seven prominent stars
Appears like a big ladle or a question mark,
three stars in the handle and four in its bowl
Moves from east to west around the pole
Not visible from some points in the
We can see during winter in the late evening
One of the most magnificent constellation in
Contains seven or eight bright stars
It also called Hunter
Three middle stars represent the belt of the
Four bright stars appear to be arranged in the
form of a quadrilateral
Brightest star in the sky
Located close to Orion
If we imagine a straight line from
middle stars of Orion towards east
we can locate the Sirius
In Northern sky
Visible in winter in the early part of the night
Looks like a distorted letter W or M
A constellation does not have only 5-10
stars. It has a large number of stars .
However we can see only the bright stars
with our naked eye.
All stars in a constellation is not same
distance, only same line of sight in the