• Terrestrial or Rocky planets – Solid surfaces – Composed primarily of rock – Have relatively high densities– Slow rotation– No rings – Few satellites

• Examples:– Mercury, Venus, Earth, and

Mars

By

Com

posit

ion

• Jovian or Gas planets – Composed primarily of hydrogen

and helium – Generally have low densities– Rapid rotation– Rings – Lots of satellites

• Examples:– Jupiter, Saturn, Uranus, and

Neptune

• Small planets– Have diameters less than 13000 km

• Example:– Mercury, Venus, Earth, Mars

• Big planets– Have diameters greater than 48000

km

• Example:– Jupiter, Saturn, Uranus and Neptune

By S

ize

• The asteroid belt between Mars and Jupiter forms the boundary between the inner solar system and the outer solar system

• Inner Planets: – Mercury, Venus, Earth, Mars

• Outer planets: – Jupiter, Saturn, Uranus, Neptune

By R

ela

tive

Posit

ion

fro

m S

un

Asteroid Belt

Dwarf Planet

Properties of Dwarf Planet

• Must orbit the Sun

• Does not emit light

• Must be smaller than 3031 miles in diameter

• Large enough so that its own gravity pulls it into the shape of sphere

• Due to weaker gravity, it is unable to clear out its orbit

List of Dwarf Planets

Following is the list of dwarf planets:

1. Eris2. Pluto3. Makemake4. Haumea5. Ceres

Eris

• Largest known dwarf planet

• The most distant member of our solar system– 3 times farther out than Pluto

• Moon 1

Eri

s

Pluto

• The god of the dead and underworld – Because it is dark and desolate

• Formerly the smallest of the nine "traditional" planets

• But in 2006, it was demoted to dwarf planet status

• Second largest dwarf planet

Plu

to

• Moon 3– Largest moon is called Charon,

which is half the size of Pluto

• Unusual orbit– Once every 248 Earth years,

Pluto swings inside the orbit of Neptune

– It stays there for twenty years– During those twenty years, Pluto

is closer to the Sun than Neptune

Makemake

• Pronounced mah-kee-mah-kee

• Located in the Kuiper Belt

• Third largest dwarf planet

• Appears reddish in color

• Moon None Makem

ake

Kuiper Belt

Haumea

• Found in the Kuiper Belt

• Has an ellipsoidal; not a sphere– Its ellipsoidal shape is thought to

result from its rapid rotation• In much the same way that a water

balloon stretches out when tossed with a spin, and not from a lack of sufficient gravity to overcome the compressive strength of its material

Hau

mea

Ceres

• Located in the asteroid belt between Mars and Jupiter

• When Ceres was first discovered – It was called a comet– Then called a planet– Then called an asteroid– Since 2006, it has been called a

dwarf planet

Cere

s

Moon

Moon

Definition:– A celestial body that makes an orbit around a

planet, including the eight major planets, dwarf planets, and minor planets

• Also referred as planet’s natural satellite

• More than 170 known natural satellites

• Moon is much smaller than its planet

Other Celestial Bodies

Solar System

Chapter - 17

Other Celestial Bodies

• Discuss the following celestial bodies:– Comet– Asteroid–Meteoroid– Black Hole

Comet

Definition– A celestial object consisting of a

nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun

• Orbits around the sun

• Comets have a coma or a tail

• They are composed of dirt and ices

Com

et

• A small, active celestial body

• Comets are characterized by dust and gas tails when in proximity to the Sun

• However, far from the Sun it is difficult to distinguish an asteroid from a comet

Hale Bop Comet

Asteroid

Definition– A relatively small, inactive

body, composed of rock, carbon or metal, which is orbiting the Sun.

• Asteroids are rocky

• Most of them exist in the asteroid belt located between Jupiter and Mars

Aste

roid

Meteoroid

Definition: – A small particle from an asteroid

or comet orbiting the Sun

Mete

oro

id

Meteor

Definition– Literal meaning The flash of

light you see– A meteoroid that is observed as

it burns up in the Earth's atmosphere - a shooting star

• They are asteroids that have succumbed to earths gravity

Mete

or

Meteorite

Definition: – A meteoroid that survives its

passage through the Earth's atmosphere and impacts the Earth's surface

• Its size can vary from big boulders to tiny rocksMete

ori

te

Meteorite Crater

Black Hole

• Definition:– It is an area in space where gravity is

so strong that even light cannot escape from it. Since light cannot escape from a black hole, it appears black

• A black hole is not really a hole and it is not empty

• It is filled with a lot of material crammed into an extremely small space

Bla

ck H

ole

• The term black hole is used because these objects look like black holes in space - since they put out no light

• How do black holes form? – When a large star runs out of fuel it can

no longer support its heavy weight.– The pressure from the star's massive

layers of hydrogen press down forcing the star to get smaller and smaller and smaller. 

– Eventually the star will get even smaller than an atom.

– Imagine that for a moment, an entire star squashed up into less space than a tiny atom

• If you make something smaller by squishing it, its gravity becomes much stronger. Imagine then, if you squish a star into the size of an atom how powerful its gravity would become

• A black hole's gravity becomes so powerful that anything, including light that gets too close, gets pulled in

Galaxy

Definition:– A group of millions of stars that

are relatively near each other

• Most stars seem to be in one or another galaxy

• Example:– Earth's own star, the Sun, is in

the Milky Way galaxy

Gala

xy

Light Year

Light Year

Definition– A light year is the distance between two

points in space that it would take light to travel when the distance between the two points in time are one year

• Light travels at 186,000 miles every second

• How big is this number?–Write 1 number/second for 8hrs a

day without stopping Would take 6 & 1/2 days to get to that number

– If you go back and fourth across the U.S. 66 times with an average speed of 60miles/hour Would take 1 year and 3weeks

• 1 year = 365 days• 1 day = 24 hours• 1 hour = 60 minutes• 1 minute = 60 seconds

No. of seconds in 1 year

= 60 x 60 x 24 x 365= 31,536,000 sec

Number of miles light travels in one year

= 186,000 x 31,536,000= 5,865,696,000,000 miles

• The closest star is 4 light years away= 4 x 5,865,696,000,000= 23,462,784,000,000 miles

• Edge of universe is 15 billion light years away

• How far is it?