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Transcript
Studying Space
Section 1: Viewing the Universe
Preview
• Key Ideas
• The Value of Astronomy
• Characteristics of the Universe
• Observing Space
• Telescopes
• Space-Based Astronomy
Section 1
Studying Space
Section 1
Key Ideas
• Describe characteristics of the universe in terms of time,
distance, and organization.
• Identify the visible and nonvisible parts of the
electromagnetic spectrum.
• Compare refracting telescopes and reflecting
telescopes.
• Explain how telescopes for nonvisible electromagnetic
radiation differ from light telescopes.
Studying Space
Section 1
The Value of Astronomy
• Astronomy: the scientific study of the universe
(Observation)
• Scientists who study the universe are called
astronomers.
• In the process of observing the universe, astronomers
have made exciting discoveries, such as new planets,
stars, black holes, and nebulas.
• By studying these objects, astronomers have been able
to learn more about the origin of Earth and the
processes involved in the formation of our solar system.
Studying Space
Section 1
The Value of Astronomy, continued
• Astronomy & Cosmology are extremely similar in nature.
Here is the distinction:
• Astronomy is the act of observation and discovery
through observation.
• Cosmology: is to understand broader questions about
the Universe, such as its origin, underlying physical laws
etc. Cosmology requires astronomy and astrophysics in
order to get data to compare to cosmological models
Studying Space
Section 1
Characteristics of the Universe, continued
Measuring Distances in the Universe
• astronomical unit the average distance between the Earth
and the sun; approximately 150 million kilometers (symbol,
AU)
• Astronomers also use the speed of light to measure distance.
• Light travels at 300,000 km/s. In one year, light travels 9.46 x
1012 km. This distance is known as a light-year.
• Aside from the sun, the closest star to Earth is 4.22 light-years
away.
Studying Space
Section 1
Observing Space
Electromagnetic Spectrum
• electromagnetic spectrum all of the frequencies or
wavelengths of electromagnetic radiation.
• Light, radio waves, and X rays are all examples of
electromagnetic radiation.
• Electromagnetic radiation is composed of traveling
waves of electric and magnetic fields that have fixed
wavelengths and therefore fixed frequencies.
Studying Space
Section 1
Observing Space, continued
Visible Electromagnetic Radiation
• The human eye can see only radiation of wavelengths in the
visible light range of the spectrum.
• The shortest visible wavelength of light are blue and violet,
while the longest visible wavelength of light are red.
• Electromagnetic radiation shorter than wavelengths of violet or
longer than wavelengths of red light cannot be seen by
humans.
• These invisible wavelengths include infrared waves,
microwaves, radio waves (at longer wavelengths than red), as
well as ultraviolet waves, X rays, and gamma rays (at shorter
wavelengths than blue).
Studying Space
Section 1
Reading check
Which type of electromagnetic radiation can be seen by
humans?
The only kind of electromagnetic radiation the human eye
can detect is visible light.
Studying Space
Section 1
Observing Space, continued
Invisible Electromagnetic Radiation
• In 1800, the scientist William Herschel discovered
infrared, which means “below the red.”
• Infrared is electromagnetic radiation that has waves
longer than those of visible light.
• The ultraviolet wavelengths, which are invisible to
humans, are shorter than the wavelengths of violet light.
• Ultraviolet means “beyond the violet.”
• The X-ray wavelengths are shorter than the ultraviolet
wavelengths. The shortest wavelengths are the gammaray wavelengths and the longest are radio waves.
Studying Space
Section 1
Telescopes
• In 1609, an Italian scientist, Galileo, built a device that
used two lenses to make distant objects appear closer
and turned it toward the sky.
• telescope an instrument that collects electromagnetic
radiation from the sky and concentrates it for better
observation
• optical telescopes : Telescopes that collect only visible
light .
• The two types of optical telescopes are refracting
telescopes and reflecting telescopes.
Studying Space
1
Observing the Universe
Section 1
Optical Telescopes
There are two basic types of optical
telescopes.
One type uses only lenses to study light and
the other uses lenses and mirrors.
What is
missing from
the
illustratons??
Studying Space
1
Observing the Universe
Section 1
Optical Telescopes
You can find the magnifying power (Mp) of a
telescope by dividing the focal length of the
objective (fo) by the focal length of the
eyepiece (fe).
Studying Space
Section 1
1 – What is the difference between astronomy &
cosmology
2 – An optical telescope can only see in the
visible light range – T or F
3 – Name the 2 types of Optical telescopes
4 – Is light a form of electromagnetic energy?
Studying Space
Section 1
Telescopes, continued
Refracting Telescopes
• refracting telescope a telescope that uses a set of lenses to
gather and focus light from distant objects
• The bending of light is called refraction.
• Refracting telescopes have an objective lens(big one) and an
eyepiece(small one).
• One problem with refracting telescopes is that the lens
focuses different colors of light at different distances causing
the image to distort.
• It is difficult to make very large lenses because they sag
distorting the image.
Studying Space
Section 1
Telescopes, continued
Reflecting Telescopes
• reflecting telescopes a telescope that uses a curved
mirror to gather and focus light from distant objects
• When light enters a reflecting telescope, the light is
reflected by a large curved mirror to a second mirror.
The second mirror reflects the light to the eyepiece,
where the image is magnified and focused.
• Mirrors in reflecting telescopes can be made very large
without affecting the quality of the image.
Studying Space
Section 1
Studying Space
Section 1
Telescopes, continued
The diagram below shows refracting and reflecting
telescopes.
Studying Space
Section 1
Studying Space
Section 1
Sometimes you get bits
of info that answer
other questions in
abstract articles.
Students have asked
where do nebulas go ?
Read the article and
what is or may be the
answer?
Studying Space
Section 1
Reading check, continued
What are the problems with refracting telescopes?
Images produced by refracting telescopes are subject to
distortion because of the way different colors of visible light
are focused at different distances from the lens and
because of weight limitations on the objective lens.
There were other problems with earth based telescopes:
Atmosphere and incidental light: Much of this has been
corrected with the use of computers.
Studying Space
Section 1
1 – Which telescope allows for the biggest
lenses
2 – Which lens would be easiest to change to
increase magnification, the objective or the
eyepiece?
3 – What factors affect the ability of a land
based telescope to see into space?
Studying Space
Section 1
Telescopes, continued
Telescopes for Invisible Electromagnetic Radiation
• Scientists have developed telescopes that detect
invisible radiation, such as a radio telescope for radio
waves.
• One problem with using telescopes to detect invisible
electromagnetic radiation is that Earth’s atmosphere acts
as a shield against many forms of electromagnetic
radiation.
• Ground-based telescopes work best at high elevations,
where the air is thin and dry.
Studying Space
1
Observing the Universe
Section 1
Radio Telescopes
radio telescope: A telescope that collects and
amplifies radio waves.
Because radio waves have long wavelengths, a
radio telescope must be built with a very large
objective, usually some form of dish antenna.
Astronomers often build several radio telescopes
close together and connect them to form one
large telescope called a VLA (Very Large Array.)
Studying Space
Section 1
The Very Large Array, one of the world's premier astronomical
radio observatories, consists of 27 radio antennas in a Y-shaped
configuration on the Plains of San Agustin fifty miles west of
Socorro, New Mexico. Each antenna is 25 meters (82 feet) in
diameter.
Studying Space
Section 1
Space-Based Astronomy
• Spacecrafts that contain telescopes and other
instruments have been launched to investigate planets,
stars, and other distant objects
• In space, Earth’s atmosphere cannot interfere with the
detection of electromagnetic radiation.
Studying Space
Section 1
Reading check
Why do scientists launch spacecraft beyond Earth’s
atmosphere?
Scientists launch spacecraft into orbit to detect radiation
screened out by Earth’s atmosphere and to avoid light
pollution and other atmospheric distortions.
Studying Space
Section 1
Space-Based Astronomy, continued
Space Telescopes (Do not copy- Raise your hand if you read
this)
• The Hubble Space Telescope collects electromagnetic
radiation from objects in space as well as visible light images .
• The Chandra X-ray Observatory makes remarkably clear
images using X rays from objects in space, such as remnants
of exploded stars.
• The Swift spacecraft detects gamma rays and X rays from
explosions and collisions of objects such as black holes.
• The James Webb Space Telescope is scheduled to be
launched in 2013 to detect near- and mid-range infrared
radiation from objects in space.
Studying Space
Section 1
Space-Based Astronomy, continued
Other Spacecraft
• Since the early 1960s, spacecraft have been sent out of
Earth’s orbit to study other planets.
• The space probes Voyager 1 and Voyager 2 investigated
Jupiter, Saturn, Uranus, and Neptune, and collected
images of these planets and their moons and they are
about to leave our solar system.
• The Galileo spacecraft orbited Jupiter and its moons from
1995 to 2003.
Studying Space
Section 1
Space-Based Astronomy, continued
Other Spacecraft, continued
• The Cassini spacecraft began orbiting Saturn in 2004. In
December 2004, the Huygens probe detached from the
Cassini orbiter to study the atmosphere and surface of
Titan, Saturn’s largest moon.
• The twin rovers Spirit and Opportunity landed on Mars in
January 2004. They confirmed that water had once been
present on Mars.
• In 2008, the Phoenix lander found ice on Mars.
Studying Space
Section 1
Space-Based Astronomy, continued
Human Space Exploration
• Spacecraft that carry only instruments and computers are
described as robotic and can travel beyond the solar system.
• The first humans went into space in the 1960’s. Between
1969 and 1972, NASA landed 12 people on the moon.
• The loss of two space shuttles and their crews, the Challenger
in 1986 and the Columbia in 2003, have focused public
attention on the risks of human space exploration. (Actually
this is the risk of using the lowest bidder on contracts)
Studying Space
Section 1
Space-Based Astronomy, continued
Spinoffs of the Space Program
• Satellites in orbit provide information about weather all over
Earth.
• Other satellites broadcast television signals from around the
world or allow people to navigate cars and airplanes.
• Inventing ways to make objects smaller and lighter so that
they can go into space has also led to improved technology.
• Even medical equipment, like the heart pump, have been
improved based on NASA’s research on the flow of fluids
through rockets.