What do the following have in common?

Why Bother???

• Exciting subject filled with new discoveries!

• Affects our every day lives!

• Mind blowing ideas that challenge our way of

thinking!

• The wave of the future!

Preview Chapter

The Cosmic Landscape

A Few Definitions

• moon or satellite: a body orbiting a planet.

A Few Definitions

• planet: a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit.

A Few Definitions

• star: a massive gaseous body held together by

gravity and generally emitting light by nuclear

reactions.

A Few Definitions

• solar-system: A collection of celestial objects (e.g. planets, comets, asteroids) orbiting around a common star.

A Few Definitions• galaxy: A collection of stars, gas, dust, and

dark matter held together by their mutual gravity.

A Few Definitions

• Universe: Consists of everything around us

IncludesEverything!

Concept Question

Which one of the following is listed in thecorrect order from smallest to largest in size?

A) star, planet, solar-system, galaxy, UniverseB) planet, star, solar-system, Universe, galaxyC) star, planet, galaxy, solar-system, Universe D) planet, star, solar-system, galaxy, Universe

Scientific Method

• observe

• hypothesize

• test

• modify,reject,or theorize

Mystery Image

Science and PseudoScience

Science and PseudoScience

Science and PseudoScience

Science and PseudoScience

Astrology or Astronomy?• Uses the positions of planets to predict human behavior• Is a branch of Physics• Uses the scientific method to interpret observations• Is considered a pseudoscience• A detailed study of all the celestial bodies in the

Universe, including planets, moons, stars, galaxies, etc.• Associates the signs of the zodiac with personality traits

Timeline of the Universe

Scientific Notation

• express very small or very large numbers in powers of ten• Format: . X 10

1.0= 1.0 X 100 (100)100.0= 1.0 X 102 (102)

1,000.0= 1.0 X 103 (103)10,000.0= 1.0 X 104 (104)

100,000.00= 1.0 X 105 (1005)

0.1= 1.0 X 10-1 (10-1)0.01= 1.0 X 10-2 (10-2)

0.001= 1.0 X 10-3 (10-3)0.0001= 1.0 X 10-4 (10-4)

0.00001= 1.0 X 10-5 (10-5)

Scientific NotationExamples:

Average Distance from the Earth to the Sun:

149,600,000.0 km 1.496 X 108 km

Mass of ant:

0.004 g 4 X10-3 g

Concept Question

Write -0.00000315 in scientific notation

A) 3.15 X 10-6

B) 3.15 X 106

C) -3.15 X106

D) -3.15 X 10-6

Concept Question

Write 7.89 X 10-6 in regular format

A) 000007.89 B) 0.00000789

C) 7890000 D) 0.0000789

Astronomical Units

1 A.U. = 1.5 X 108 km

Average Distance from the Earth to the Sun Astronomical Unit

Distance that light travels in a year Light Year

speed of light in a vacuum: c = 3 x105 km/s (186,000 mi/s)so one light second: 3x105 km

and one light year: 9.46x1012 km more practical to use

Looking Backwards in Time

on a planet orbittinga distant star

70 years old

here on Earth

70 years old

55 light years away

15 years old

68 light years away

2 years old

Because of the finite speed of light, we are able to look backwards in time!!!

Astronomical Distance Scales are Astronomical!

Alpha Centauri: 4.2 light years away

Andromeda Galaxy: 2.4 million light years away

Galaxies in the Hubble Deep Field: as far as billions of light years away

The Sun: 8.3 light minutes away

The finite speed of light gives us a fossil record of the history of the Universe!!!!

The Moon: 1.3 light seconds away

Astronomical Distance

Scales are Astronomical!