stars, galaxies, and the universe - mrbrysonscience - … stars • the main characteristics used to...
Post on 25-Mar-2018
225 Views
Preview:
TRANSCRIPT
Stars, Galaxies, and the
Universe
Constellations
Constellations are patterns of stars in the
sky.
Electromagnetic Radiation • Visible light – the light we see with our eyes
• Light is a form of electromagnetic radiation, or energy that can travel directly through space in the form of waves.
• The electromagnetic spectrum includes the entire range of radio waves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.
Types of Telescopes • Most telescopes collect and focus different types of
electromagnetic radiation, including visible light.
• A refracting telescope uses convex lenses to focus light.
• A convex lens is a piece of transparent glass, curved so that the middle is thicker than the edges.
• A reflecting telescope has a curved mirror in place of an objective lens.
• A radio telescope is a device used to detect radio waves from objects in space.
Four Views of the Crab Nebula - Telescopes
• Different type of telescopes collect
electromagnetic radiation at different
wavelengths. Astronomers are able to
learn a great deal about the Crab Nebula
by examining these different images. The
images are shown at different scales.
Building Vocabulary Read the definition and sentence of each term.
Then write a definition of each term in your own words.
- Telescopes
Key Terms: Examples:
telescope A telescope helps to make faraway objects look
closer. It is a very valuable tool in astronomy.
electromagnetic
radiation
Electromagnetic radiation is a type of energy that
travels as waves through space. It includes visible
light.
visible light Scientists call the light you can see visible light.
wavelength The distance between the crest of one wave and the
crest of the next wave is called wavelength.
spectrum If you shine white light through a prism, the light
spreads out to make a range of different colors with
different wavelengths, called a spectrum.
Key Terms: Examples:
optical telescope
refracting telescope
convex lens
reflecting telescope
radio telescope
observatory
A telescope that uses lenses or mirrors to collect and
focus visible light is called an optical telescope.
A refracting telescope uses convex lenses to gather
and focus light.
A convex lens is a piece of transparent glass, curved
so that the middle is thicker than the edges.
A reflecting telescope uses a curved mirror to collect
and focus light.
Devices used to detect radio waves from objects in
space are called radio telescopes.
An observatory is a building that contains one or
more telescopes.
Observatories • Observatory – a building that contains one or more
telescopes
• Often times, scientists will place telescopes onto
satellites.
• Example - The Hubble Telescope
• Spectrograph – breaks the light from an object into
colors and photographs the resulting spectrum
• Astronomers use spectrographs to get information
about stars, including their chemical compositions
and temperatures.
CHARACTERISTICS OF
STARS • Galaxy – contains hundreds of
billions of stars
• Universe – all of space and
everything in it (contains billions
of galaxies)
• Light-year – the distance that
light travels in one year
Measuring Distances to Stars - Characteristics of Stars
• Astronomers often use parallax to
measure distances to nearby stars.
Parallax
- Characteristics of Stars
• Parallax is the apparent change in position
of an object when you look at it from
different places.
CLASSIFYING STARS • The main characteristics used to classify stars are:
1. Size 1. Neutron star (smallest star)
2. White dwarf star
3. Medium-sized star
4. Giant star
5. Supergiant star (largest star)
2. Temperature • A star’s color reveals its temperature
3. Brightness • Apparent magnitude – a star’s brightness as seen from
Earth.
• Absolute magnitude – the brightness a star would have if it were at a standard distance from Earth
Star Size - Characteristics of Stars
• Stars vary greatly in size. Giant stars are
very large stars; typically 10 to 100 times
larger than the sun and more than 1,000
times the size of a white dwarf.
The Hertzsprung-Russell
Diagram • Astronomers use H-R diagrams to classify stars and
to understand how stars change over time. Most of the stars in the H-R diagram form a diagonal line called the main sequence.
LIVES OF STARS
• Pulsars – Pulsating Radio Sources (Neutron stars)
• Nebula – large amount of gas and dust spread out in an immense volume
• Protostar – the earliest stage of a star’s life
• A star is born when the contracting gas and dust become so hot that nuclear fusion starts.
The Lives of Stars - Lives of Stars
• A star’s life history depends on its mass. After a star runs
out of fuel, it becomes a white dwarf, a neutron star, or a
black hole.
DEATHS OF STARS • White dwarf – the blue-white hot core of the star that is
left behind
• Supernova – a dying giant or supergiant star can suddenly explode, leaving the star to blaze millions of times brighter until the star dies --- the explosion is called a supernova
• Neutron stars – material that forms after a supernova --- they are much smaller and denser than white dwarfs
• Quasars – distant bright objects
Black Holes - Lives of Stars
• The remains of the most massive stars
collapse into black holes. Here, a black
hole is shown pulling matter from a
companion star.
Life Cycle of a Sun-Like Star As you read, make a flowchart that shows the stages in
the life of a star like the sun. Write each step of the process in a separate box in the flowchart in the order that it occurs.
Protostar forms from a nebula.
A star is born as fusion begins.
The star stays on the main sequence for billions of years.
The star begins to run out of fuel.
The star becomes a supernova, then a white dwarf, then a black dwarf.
STAR SYSTEMS AND
PLANETS • Star systems – stars are members of
groups of two or more stars called star
systems
• Binary stars – star systems with two
stars
• Eclipsing binary – a system in which
one star blocks the light from another
GALAXIES
• Galaxies are classified into three main categories:
• Spiral galaxies
– Has the shape of twin spirals
• Elliptical galaxies
– Looks like flattened balls
• Irregular galaxies
– No regular shape
Structure of the Milky Way
- Star Systems and Galaxies
• Our solar system is
located in a spiral
galaxy called the
Milky Way. From the
side, the Milky Way
appears to be a
narrow disk with a
bulge in the middle.
The galaxy’s spiral
structure is visible
only from above or
below.
Scientific Notation • The bright star Deneb is about 3,230 light years
from Earth. To express this number in scientific
notation, first insert a decimal point in the original
number so that you have a number between one
and ten. In this case, the number
is 3.23.
• To determine the power of 10, count the number
of places that the decimal point moved. Here the
decimal point moved three places.
• 3,230 light-years = 3.23 X 103 light-years
• According to the Big Bang Theory, the
universe formed in an enormous explosion
about 10 to 15 billion years ago.
Theory
Evidence
Big Bang
Moving galaxies: All
galaxies are moving away
from us and from one other.
Cosmic background radiation: This glow comes
from thermal energy left over from the big bang.
- The Expanding Universe BIG BANG THEORY
Formation of the Solar System
- The Expanding Universe
The solar system formed from a collapsing
cloud
of gas and dust.
Retreating Galaxies - The Expanding Universe
All distant galaxies are moving rapidly away
from our galaxy and from each other.
Moving Galaxies
- The Expanding Universe
• The galaxies in the universe are like the
raisins in rising bread dough.
top related