Download Exploration of Space

Chapter 16- What is Astronomy?
EXPLORATION OF SPACE
Ancient Astronomy
 People have wondered about the skies for
thousands of years
 Astronomy- the study of space and all the
objects in it
 Predicting eclipses of the Sun date back to
First Century B.C. (figure 16.2)
Ancient Astronomy
 Mercury, Venus, Mars, Jupiter, and Saturn
were known 5,000 years ago
 No new planets were found until 1781
Uses of Astronomy
 Most societies depended on the changing of
seasons
 Farmers had to know when to plant crops
 Sailors used positions of stars to navigate the
sea
Modern Astronomy
 1609- Galileo Galilei used simple telescope to
look at Moon and other objects
 Today astronomers use telescopes, satellites,
space probes to see millions of miles
Modern Astronomy
 What do modern astronomers study?
 Universe- everything that exists
 Solar system- includes the Sun and all the
bodies in space that orbit it
 Cosmologists study how the universe began
and how it will end
Early Beliefs about Earth
 2000 B.C.- Calendar based on movements of
the Sun and Moon
 Earth believed to be flat
 Aristotle- claimed Earth was at the center of
the universe
 Copernicus- claimed Sun was center of
universe
(Brahe, Kepler, Galileo, Newton supported)
How the Universe Formed
 Scientists believe the universe began 13
billion years ago called the Big Bang
 Galaxy- huge collection of stars, gas, and
dust
 Most distant galaxies formed soon after the
Big Bang
Answers from Space
 1957- Launch of Russian satellite Sputnik
 United States launched Explorer 1 one year
later
 Hope to answer more questions about the
universe.
How did the solar system form?
Is there intelligent life elsewhere in the
universe?
Hubble Space Telescope
 Launched into space in 1990
 Named after Edwin Hubble- American
astronomer
 Has taken many pictures of distant planets
and galaxies impossible to see from Earth
Hubble Space Telescope
http://hubblesite.org/
Astronomical Units
 Distance between Earth and sun is 149,597,
870 km or 150 million k,
 Astronomical unit (AU)- 1 AU is equal to 150
million km
 Used to measure distances in space,
especially between planets
Light-Years
 Light-year- is equal to the distance light
travels in one year
 Light travels through space at a speed of
300,000 km per second
 Light-year= 10 trillion km
 Light from Sun reaches Earth in about 8 min.
 Light from North Star reaches Earth in about
431 years!
Parallax
 Parallax- is the apparent change in the
position of a distant object when seen from
two different places
 By measuring how much the nearby star
appears to move, astronomers calculate how
far away the star actually is
 Nearby stars have a larger angle of parallax
than distant stars
Parallax
Artificial Satellites
 Satellite- is any object, natural or artificial
that follows a curved path around another
object in space
 Orbit- curved path of the object
 Most satellites are launched into 4 main
orbits
 Circular orbits- 250 km above Earth
 Polar orbits- 800 km above Earth
 Figure 16-28 page 400
Uses of Satellites
 Thousands of artificial satellites have been
placed in orbit around Earth
 Global Positioning System (GPS) has 24 satellites
in circular orbit
 Meteorologists are able to measure temperature
 Allows geologists to understand climate changes
Space Probes
 Explore much of space without carrying people
 Can go places that would be too far or too
dangerous for astronauts to travel
 Galileo space probe sent to Jupiter- entered
atmosphere in 1995
 Cassini- launched in 1997, reached Saturn in
2004
Space Probes
Galileo Space Probe-1995
Sent to Jupiter
Cassini Space Probe-1997
Sent to Saturn
International Space Station
 Launched in 1998 by the United States and
Russia
 Many parts have been carried into orbit by
space shuttles or other rockets
 Contains laboratories, living quarters,
docking bays for shuttles, and solar panels for
energy