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Transcript
Exploring Space
Looking from Earth
Telescopes are used to see objects that
are far away.
 The largest telescopes are up to 300m
wide
 There are 3 types

Reflecting
 Refracting
 Radio

Optical Telescopes


Refracting and
reflecting telescopes
are both types of
optical telescopes
They use lenses and
mirrors to produce
magnified images


Professional
astronomers house
the telescopes in
observatories
The Hubble Space
Telescope was
launched in 1990 in
order to get better
quality picture of the
universe.
Radio Telescopes

All stars radiate energy throughout the
electromagnetic spectrum

Light, x-rays, radio waves, microwaves, etc…
Radio telescopes study the radio waves
 A computer takes data about the radio
waves and makes a map
 The largest radio telescope in the world is
300m wide

Satellites
Space exploration began in 1957 with the
Soviet satellite Sputnik I
 Today thousands of artificial satellites orbit
the Earth
 Space probes carry instruments to gather
information and send it back to Earth.
 There have been several important probes
sent out by the National Aeronautics and
Space Administration (NASA)

Mariner 2



Launched in August
1962
First successful
planetary probe
Verified high
temperatures in
Venus’ atmosphere
Viking 1



Launched August
1975
Mapped Martian
surface
Searched for life on
the surface
Pioneer 10
Launched March 1972
 First probe to encounter Jupiter
 Sent back photographs and data

Voyager
2 probes were launched in 1977
Voyager 1



Voyager 2


Flew past Jupiter & Saturn
Flew past Jupiter, Saturn, Uranus, and
Neptune
Sent back information from all the planets
it visited
Galileo

Launched in 1989

Reached Jupiter in 1995
Sent a probe in to the atmosphere
 Returned data on composition,
temperature, and pressure
 Also studied Jupiter’s moon’s, rings, and
magnetic fields

Race to the moon
In 1961, President John F. Kennedy called
for the US to put a person on the moon
and began the space race.
 The race to the moon was undertaken in 3
projects

Project Mercury
 Project Gemini
 Project Apollo

Project Mercury
Goal: To orbit a piloted spacecraft around
the Earth and bring it back safely
 Significant Events

May 5, 1961 – Alan Sheppard became the
first US citizen in space
 1962 – John Glenn became the first US
citizen to orbit the Earth

Project Gemini
2 astronauts in the same Gemini
spacecraft orbited the Earth
 One team met and connected with another
space craft in orbit.
 Ranger & Surveyor – Proved we could
land on the moon

Project Apollo
Goal: to reach the moon
 July 20, 1969: Apollo 11 landed on the
lunar surface
 Neil Armstrong became the first man to set
foot on the moon.
 “One small step for man, one giant leap for
mankind.”

Beyond our Solar System

Characteristics of Stars
Color
 Temperature
 Brightness
 Mass

Color and Temperature
Color tells us temperature of a star
 Very hot stars = temperatures above
30,000 K are blue
 Stars between 5,000 K and 6,000 K
appear Yellow
 Cooler stars under 5,000 K appear Red

Stellar Mass
Binary stars- 2 stars pulled together in
orbit by the force of gravity
 They orbit each other around a center of
mass

If the center of mass is known than we can
calculate mass of the stars
 Example- if the stars have equal mass the
center of mass is exactly halfway between
them

Measuring Star Distance
Shifting of a nearby star due to the orbital
motion of Earth
 How is it done?

Photograph a nearby star
 Photograph the same star 6 months later
 Calculate distance from star by the amount
and angle of the shift

Light Years
Distances to stars are so large that we
need a special unit to measure them
 1 Light Year is the distance light travels in
one years time

9.5 X 1012 Kilometers
 Or 9.5 trillion Kilometers
 Proxima Centauri is 4.3 light years away
 (9.5 trillion kilometers X 4.3)

Stellar Brightness
Magnitude = measure of star’s brightness
 Apparent magnitude – how bright a star
appears from Earth
 Factors that effect apparent magnitude

How big it is
 How hot it is
 How far away it is

Absolute magnitude
Actual brightness of a star
 2 stars with the same absolute magnitude
may not necessarily have the same
apparent magnitude

Stellar Evolution
Stars start off as dark clouds of 92%
hydrogen, 7% helium, < 1% heavier
elements
 Gravity squeezes matter inward and the
interior heats up
 Protostar- early phase where star is
heating up (spans 1 million years)

Star Birth
When the core of the Protostar reaches 10
million K, pressure is so great that nuclear
fusion occurs- a star is born
 Heat from fusion of hydrogen is released
 When balance is maintained from inward
pressure (gravity) and outward pressure
(heat) the Main-Sequence stage is
reached

Main-Sequence Stage
Hydrogen fusion occurs for a few billion
years
 Stars age at different rates

Blue stars- burn so hot they deplete hydrogen
quickly (few million years)
 Red/Yellow stars- burn cooler so their
hydrogen lasts longer (our sun 10 billion
years)

Red Giant Stage
Hydrogen depleted in core leaving a
helium core
 Core loses outward heat pressure and
begins to collapse
 As core contracts it grows hotter by
converting gravitational energy into heat
energy- this energy starts to fuse
hydrogen in outer layers

Red Giant Stage
The heat energy expands stars outer layer
resulting in a giant body hundreds to
thousands of times larger than its main
sequence size
 Previous events are all well documentedwhat happens next is based on theory

Burnout and Death
Stars eventually run out of fuel and
collapse due to gravity
 Death of different size stars


Low-mass stars
 Remain
in main-sequence until fuel runs out and
than collapse into white dwarf
 White dwarf- extremely dense remains of stars
 Black dwarf- a white dwarf that has cooled down

Medium mass stars
Reach giant phase fusing hydrogen and
helium
 Then collapse from red giants to white dwarfs

 White

dwarfs are extremely dense remains of stars
Cast the outer layer creating an expanding
cloud of red gas (called planetary nebula)

Massive stars

Have short life spans and die out with a
brilliant explosion (supernova)
 During
a supernova the outer layer of the star is
ejected while the core collapses
 Star becomes a million times brighter than the
prenova phase
 If one of the nearest stars to Earth went into
supernova it would be brighter than our sun
Black Holes
During a supernova remnants of stars 3X
the size of the sun collapse into small
dense objects (Black Holes)
 These black holes have gravitational
energy so strong that even light cannot
escape their surface
 How do we find them?


Look for the heat emitted as matter is being
pulled in
Galaxies
Group of stars, dust, and gases held
together by gravity
 Billions of stars in our galaxy- The Milky
Way

100,000 light years across
 Spiral galaxy

Types of Galaxies



Spiral
 Great concentration of stars
near the center
 Large galaxies containing
billions of stars
Elliptical
 Round to oval in shape
 Smaller galaxies
Irregular
 Composed of mostly young
stars
Hubble’s Law

Red shifts- Hubble observed that most
galaxies have red shifts
Red shifts show that light waves are being
stretched
 This means that Earth and the source of the
light waves are being moved away from each
other
 Greater red shifts mean faster speeds

Hubble’s Law

Galaxies further away have greater red
shifts and therefore are moving faster


This discovery led to the Big Bang Theory


The Universe is Expanding!!!!
At one time the entire universe was confined
to a dense, hot, supermassive ball. 13.7
billion years ago a violent explosion occurred
hurling this material in all directions
Evidence- 1) red shifts 2) cosmic radiation
produced during the explosion
What is the fate of our
Universe?
Expansion lasting forever as stars die out
and the universe is filled with dense black
dwarfs and black holes
 The Big Crunch- will gravity pull everything
back into a high density, high energy mass
as it was before the big bang?
