Stars and the solar system
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Transcript of Stars and the solar system
Stars and the solar system
Stars and the solar system
Milky way galaxyMilky way galaxy
The milky way galaxy which is our own galaxy . It contains
about two hundred billion stars and other countless objects . The stars of this
galaxy spread from its centre like a spiral . It is therefore known as a spiral galaxy .
The StarsThe StarsStars are very hot and huge heavenly objects made up of very hot gases . They appear
like dots only because they are very very far
away from us . The nearest star to the
earth is the Sun itself . The next nearest star
is the alpha centuari or proxima centuari .
After the sun it is the star Sirius which is the
brightest star in the sky .
Pole StarPole StarThe pole star known as dhruv tara in hindi is a
special star present in the northern hemisphere . This star unlike the other stars, appears to be fixed at one
place . Because of this special feature, the star has
been very useful to travellers. The pole star
defines the north direction . The other directions can
then be defined with respect to this direction .
ConstellationsConstellationsA close and careful
observation of the stars on a clear night reveals that some of these stars
appear to form some kind of patterns that appear to resemble some familiar shapes. Such a group of
stars is known as a constellation . Some
prominent constellations are Orion, Ursa major,
Ursa minor and Cassiopeia .
The MoonThe MoonThe moon, our nearest
neighbour in space, is a natural satellite of the earth . It does not
have any light of its own . Its observed silvery glow is only due
to the light of the sun reflected by its surface . We all observe that the shape and size of the front or bright part of the moon appears to change gradually
everyday . It takes nearly 29.5 solar days for the moon to make one complete revolution around
the earth .
Phases of the MoonPhases of the MoonAlthough half of the moon is
always illuminated by the sun’s light, the lighted up portion of the moon appears to change
shape . This is due to change in relative position of the earth , sun and the moon . On a full moon day, the earth lies in
between the moon and the sun . On this day the full face of the
moon is visible . On a new moon day the moon is on the
other side of the earth hence we cannot see it . On the days
following the new moon day the illuminated part of the moon appears in crescent shape .
Moon’s surfaceMoon’s surface
On July 20, 1969 the American astronaut Neil Armstrong landed
on moon for the first time, followed by Edwin Aldrin . They
found moon’s surface to be dusty and barren . Crates, upto
hundreds of kilometers wide, cover its surface . It also has large no. of mountain ranges, valleys and lava plains . The moon does not possess any atmosphere and there is no
whether . The temperature on moon is ranging from 100’C to
173’C at night .
The Solar System The Solar System Our solar system consists of the sun and the eight
planets . The eight planets are mercury, Venus, earth,
mars, Jupiter, Saturn, Uranus, and Neptune . The solar system also
consists of minor planets or asteroids a hosts of
comets and meteors . The gravitational pull between the sun and these bodies
keeps them revolving them around it .
sunsunThe solar system is dominated by the sun, which accounts for almost 99.9% of the matter of the whole system . The sun is
also the source of almost energy in the solar system .
The sun is essentially a sphere of hot gases . The temperature of the bright disc is about 6000
K . The radius of the sun is almost 100 times of the earth and its mass is about a million times the mass of the earth .
MercuryMercuryMercury lies closer to the sun than
any other planet . It is a dry, hot and virtually airless planet . It has craters like the moon . Mercury is
much smaller in size than the earth . It is occasionally visible just before sunrise or immediately after sunset . Hence, it is often known as the morning or evening star . Being close to the sun, it takes only 88 earth days to go around
the sun once .
VenusVenusVenus is the brightest object in our after the sun and the moon . Its bright appearance is due to its cloudy atmosphere which reflects almost three-fourth of
the sunlight falling on it . Venus is almost the same size as the
earth but rotates relatively slowly around its axis . It rotates
from east to west . Venus is even hotter than mercury
because of CO2 in its atmosphere . This gas traps
most of the sun’s heat . Venus is also called evening or morning star because it is only visible
these times .
EarthEarthThe earth is a very unique and
special planet of our solar system . It has life on its surface
because of the presence of water, suitable atmosphere and
a blanket of ozone layer and right size and right distance
from the sun so that it has right temperature range and gravity .
The earth also has an ozone layer which absorbs the
ultraviolet radiation from the sun and protects us from its harmful
biological effects .
Mars Mars Mars usually appears reddish in colour hence, it is also often known as the red planet . Its
surface resembles a cold, high altitude desert . Its surface temperature and surface
pressure both are very low . The diameter of mars is only a little more than half of that of earth . Mars has two natural satellites or moons named Phobos and Deimos . Mars
has a low average density as compared to the earth .
Jupiter Jupiter
Jupiter is the largest of all planets . Its volume is 1300
times more than that of earth . Jupiter consists mainly of
hydrogen and helium in gaseous form . Its cloud cover
is made up of methane, in gaseous form, with some
ammonia in crystalline form . Jupiter has at least 63 known
moons. The largest four are called Io, Europa, Ganymede, and
Callisto.
SaturnSaturnSaturn is quite similar to Jupiter in size, mass and
composition . It is the second largest planet of the solar
family . It is distinguished by its very unique and special
system of rings . These rings give it a beautiful appearance .
These can only seen clearly with the help of a telescope . As of April 2014, there are 62 known satellites of Saturn .
URANUSURANUS
Uranus is also a very large planet . It in fact is the third largest planet of the solar
system . Hydrogen and methane have been detected in the atmosphere of this planet .
This planet is observed to have blue-green colours .
Uranus has 27 moons that we know of. Five of the moons are
large and the rest are much smaller. The five large moons
are called Miranda, Ariel, Umbriel, Titania, and Oberon.
NeptuneNeptune
Neptune is very far away f rom the sun and is
v is ib le only through a te lescope . I t has been named af ter the roman
sea god Neptune . Neptune has th i r teen
moons that we know of . The largest moon is
Tr i ton .
Minor bodies in the solar system
Minor bodies in the solar system
Apart from the sun and the planets there are some minor bodies in solar sys tem . They
are asteroids, meteors and comets .
ASTEROIDSASTEROIDS
Asteroids are very small planets or planetoids that are found mainly in a belt between the orbit of mars and Jupiter . Astronomers
have discovered more than 500 asteroids which are larger than 48 km in diameter . Ceres is the largest of the asteroids
discovered till now .
CometsCometsThe name comet means a
ha i ry s tar . Comets are re la t ive ly smal l and icy
ce lest ia l bodies revolv ing around the sun . Comets
are only v is ib le when they are near the sun, th is is
because the in tense so lar heat vapor izes par ts o f
the i r icy mat ter and creates the i r i l luminated
ta i l . The best known per iod ic comet is Hal ley 's
comet . I t appears a f ter every 76 years .
Meteors and meteoritesMeteors and meteoritesMeteors are re la t ive ly smal l bodies that a lso revolve round the sun.
some of them may enter in to the ear th ’s
a tmosphere f rom outer space . Th is makes them
shine br i l l i ant ly l ike f i rebal ls . We ca l l them
fa l l ing s tars . Some meteors that are so large
that a par t o f them is ab le to reach the sur face of ear th , they are ca l led
meteor i tes .
Artificial satellitesArtificial satellitesArtificial satellites are man-made
objects which can be made to revolve around the earth . Artificial satellites perform
various tasks, such as transmitting radio, telephone and television signals, sending back
information for weather forecasting, military surveillance
and for locating mineral resources . Satellites that are being put to the maximum use
are the geostationary satellites . A geostationary satellite appears to remain fixed with respect to a
particular point .
Group members Group members
RISHABH CHAUHAN
ISHANT CHAUHAN
VINAY KADYAN
MD. ARSH
HARSHIT CAHUAHAN
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