Universe PPT
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Transcript of Universe PPT
ORIGIN OF THE
SOLAR SYSTEM
ORIGIN OF THE SOLAR
SYSTEM
ORIGIN OF THE SOLAR SYSTEMOur solar system began forming about 5 billion years ago,
when a cloud of gas and dust between the stars in our Milky
Way Galaxy began contracting. A nearby supernova—an
exploding star—may have started the contraction, but most
astronomers believe a random change in density in the cloud
caused the contraction.
Once the cloud—known as the solar nebula—began to
contract, the contraction occurred faster and faster. The
gravitational energy caused by this contraction heated the
solar nebula.
This spin kept the nebula from forming a sphere; instead, it
settled into a disk of gas and dust.
HOW DID THE SOLAR SYSTEM FORMED?
Astronomers think that the solar system may have come from a swirling cloud of gas and dust. First a star, our Sun, formed from a clump in the cloud. It began as a spinning ball of gas at the center of the cloud. Then the planets, their moons, and the other objects in the solar system formed from the leftover gas and dust.
Formation of the Solar System
s
Evidence for Ongoing Planet
Formation
Many young stars in the Orion Nebula are
surrounded by dust disks:
Probably sites of planet formation
right now!
PLANETS AND ITS SATELLITES
Two Kinds of Planets
Terrestrial (earthlike) planets: Mercury, Venus,
Earth, Mars
Jovian (Jupiter-like) planets: Jupiter, Saturn,
Uranus, Neptune
Terrestrial Planets
Four inner planets of the solar system
Relatively small in size and mass (Earth is the
largest and most massive)
Rocky surface
Surface of Venus can not be seen directly from Earth because of its
dense cloud cover.
The Jovian PlanetsMuch larger in mass
and size than terrestrial planets
Much lower average density
All have rings (not only Saturn!)
Mostly gas; no solid surface
SUN
SUN
The Sun provides
Earth with huge
amounts of energy in the form of heat
and light. Without the Sun, life on Earth would
not be possible.
MERCURY
MERCURY
Mercury is the planet closest to the Sun. It
is dry, hot, and nearly airless.
VENUS
VENUS
Days on Venus seem endless. Venus is the
second planet from the Sun. One day on Venus is as long as 243 days
on Earth.
EARTH
EARTH
EARTH HAS 1satellite.
cc
MOON
MARS
MARSIts surface is
like a very cold desert. There is ice, but no liquid water.
Mars has reddish-brown rocks and soil. We often call Mars the red
planet because from Earth, it looks bright red in the night sky.
This animation traces a system of canyons on Mars.
The Pathfinder mission, which visited Mars in 1997, did many tests of the planet’s soil and rocks. It also sent back lots of photos,
like this one.
Scientists believe that Mars once had
water on its surface, based on evidence like the
channels shown in this photo.
Olympus Mons is not only the biggest mountain on Mars, it’s the biggest in the whole solar
system!
MARS HAS 2 satellites.
Deimos, lower left, and Phobos, lower right. An asteroid called Gaspra, top, is
shown for comparison.
JUPITER
JUPITER
Jupiter is the fifth planet from the Sun and the biggest planet in our solar system. More than 1,300 planets the size of Earth could fit inside Jupiter.
The impact of Comet Shoemaker-Levy. The comet was torn apart by Jupiter’s gravitational field as it approached the planet.
JUPITER HAS 69 satellites.
CALLISTO
Callisto is Jupiter’s second largest moon. Its surface is covered by many large
craters.
EUROPA
The surface of Jupiter’s
moon Europa is covered with ice.
Astronomers think the ice
may lie on top of huge
oceans of liquid or
slushy water.
GANYMEDE
Ganymede, Jupiter’s
largest moon, is also the
biggest moon in the solar
system!
Io
Jupiter’s moon Io has the
most active volcanoes in the solar
system.
SATURN
SATURN
Saturn’s rings are pretty
thin. In places they are only
16 feet (5 meters) thick. The rings are
made of dust, pieces
of rock, frozen gases,
and ice.
SATURN HAS 63
satellites.
TitanThe largest
moon of Saturn is
Titan. Titan is larger than the planets Pluto and Mercury. It
has an atmosphere
made of nitrogen gas.
RHEA
DIONE
MIMAS
TETHYS
JANUS
HYPERION
ENCELADUSSaturn's moon
Enceladus is the brightest moon
in the solar system. The cold, distant world reflects
over 90 percent of the sunlight it receives, giving
its surface about the same reflectivity as
new-fallen snow.
PHOEBE
IapetusSaturn's third largest
moon, Iapetus, has two sharply contrasting
types of terrain.
URANUS
uranus
Uranus is covered with
a kind of smog. Smog on Earth is
pollution that comes
mostly from cars that
burn gasoline. Sunlight changes
fumes from the cars to
smog.
URANUS HAS27
SATELLITES.
titania
Ariel
Astronomers think Ariel is made of ice and rock.
Oberon
umbriel
Miranda
NEPTUNE
Neptune
Neptune has the fastest
winds in the solar system.
Neptune wobbles as it
orbits the Sun.
NEPTUNE HAS 13 SATELLITES.
Triton
Triton is largest of Neptune’s moons. It has few
craters, but many
cracks in its surface.
Nereid
PLUTO
Pluto
PlutoScientists are not sure what Pluto is made of. They think it’s made of rock and ice. They know
that Pluto is very cold because
it is so far from the Sun.
Pluto has 3 SATELLITES.
Charon
Planetary Orbits
Plut
oNe
ptun
eUran
usSaturn
Jupi
terM
ars
Earth
VenusMercury
All planets in almost circular (elliptical)
orbits around the sun, in approx. the same
plane (ecliptic).
Sense of revolution: counter-clockwise
(Distances and times reproduced to scale)
HOW SMALL
AREWE ?
WATCHEARTH
SHRINK!
I THANK THEE.