Download The Planets in our Solar System Solar System Basics

The Planets in our Solar System
Solar System Basics
• Our solar system is not
only made of the Sun,
the nine planets and
their satellites, but also
asteroids and comets.
• All celestial bodies
revolve around the
sun.
Formation of the Planets
• The particles in space
surrounding the sun
contracted to form the
planets of the solar
system.
• *A planet is a celestial
body revolving around a
star.
• Our solar system has 9
planets revolving around
our star – the Sun.
• The characteristics of each planet were determined
by where each planet formed in relation to the Sun.
• The various temperatures created different elements.
• Heavier elements formed closer to the heat of the
Sun, lighter elements formed farther from the Sun.
More on planet formation . . .
• Temperature and distance from the Sun
influenced the condensation of various
substances within the evolving solar system.
• Eventually, the condensing material merged
to form large bodies hundreds of kilometers
in diameter.
• These bodies were
called planetesimals.
• The planets began to
form from the
collision of these
planetesimals.
Two Types of Planets
• The Inner Planets
– Terrestrial
– Made of heavy,
solid elements
– Mercury, Venus,
Earth, Mars
• *Gas Giant Planets:
– The Outer Planets
– Gaseous
• About 15 times larger than
Earth
• Composed of hydrogen and
helium
– Light, very low density
– Jupiter, Saturn, Uranus, Neptune
To be or not to be . . .
• Pluto is weird 
– Solid surface but low
density; the best of
both worlds!
• Planet:
– Yes, solid body
orbiting star.
– No, orbit too far off
and not regular.
• Decide for yourself!!
The Birth of the Sun
• The sun formed from
the dense concentration
of gas at the center of
the solar nebula.
• As the gas and dust
condensed, the
temperature and
pressure at the center
increased.
• The temperature and
pressure became so
great, nuclear fusion
began.
The Sun (. . . Continued)
• Nuclear fusion causes lighter atoms, like
hydrogen, to fuse and become heavier
atoms, like helium.
• This reaction releases tremendous amounts
of energy.
• The sun releases this energy in the form of
thermal energy and light.
Galaxies . . .
• The sun is the star of
our solar system, but it
is only one of millions
of stars in the Milky
Way Galaxy.
• A *galaxy is a system
containing millions of
stars held together by
gravity.
The Neighborhood . . .
• *A Local Group of
galaxies is a group of
30 galaxies, of which
the Milky Way is a
part.
• The local group is part
of a 10,000 unit
supercluster
Proxomity
• *Astronomical Unit (AU)
– The distance between the
Earth and the Sun
– ~ 93 million miles.
• A *light year is the
distance light travels in
one year.
~ 9.7 trillion km.
Other Objects in the Solar System
• Asteroids
– Small, rocky bodies that orbit the Sun.
• Comet
– A small body that revolves around the Sun in
an elliptical orbit.
– It is a body of ice with a rocky core
– When it nears the Sun, the ice melts and is
illuminated by the sun, forming the tail.
Meteoroids, Meteors, and
Meteorites!
• Meteoroids
– A fragment of an asteroid that enters Earth’s
atmosphere.
• Meteor
– A meteoroid that burns up as it enters Earth’s
atmosphere. (Shooting Star)
• Meteorite
– A meteor that hits the Earth
Time for lab . . .
Lab 8-5: The Solar System
Pages 331 - 334
General Solar System Info . . .
• (#1) The two largest
planets in our Solar
system are Jupiter and
Saturn ~ both gaseous
planets.
• (#2) Venus is the
planet closest in size
to the Earth.
• (#3) The inner,
terrestrial planets are
much smaller than the
outer, gaseous planets.
• (#4) According to the
ESRT, Jupiter’s
diameter is about 11
times greater than
Earth’s.
• (#5) The sun’s
diameter is 1,394,000
km. If we used the
scale 1 mm = 700 km,
the sun would be
almost 2000 mm (1.9
km)!
• (#6) The outer planets
are much farther apart
than the inner planets.
• (#7) The planets that
are closest to Earth
are Mars and Venus.
• (#8) Which planet has
the longest period of
revolution?
• Neptune at 165 years.
• Why?
• Check out the ESRT;
It’s the farthest planet
from the sun!
• (#9) Which planet has
the longest period of
rotation?
• Venus
– 243 days
– Earth rotates in 24
hours!
• (#10) How many
moons orbit around
Jupiter?
• 16, compared to 1 for
Earth, 18 for Saturn
and 21 for Uranus!
Conclusion . . .
• All of the planets, including Jupiter, are
dwarfed by the size of the sun
• The Earth is close to the sun in comparison
to other, “nearby” stars and galaxies.