Studying Space
Section 1: Viewing the Universe
Section 1
Studying Space
Section 1
26.1 board questions
• What comes to mind when you hear
about new astronomical discoveries?
Think about what an astronomer does
and then draw a picture, with caption,
of an astronomer at work.
• What’s the difference between a
refracting and reflecting telescope?
Studying Space
Section 1
Project
• Apparent Motions of the Moon
• Make daily observations of the moon to determine the
path and phases of the moon.
– Take pictures and a log book of the moon
– Every night at the same time
– Try to determine the path and the phases of the moon
• 1/7/2014-2/7/2014
Studying Space
Section 1
The Value of Astronomy
• astronomy the scientific study of the universe
• 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
• Studies of how stars shine may one
day lead to improved or new energy
sources on Earth.
• Astronomers may also learn how to
protect us from potential
catastrophes, such as collisions
between asteroids and Earth.
Studying Space
Section 1
Characteristics of the Universe
Organization of the Universe
• The nearest part of the universe to Earth is our solar system.
• The solar system includes the sun, Earth, the other planets,
and many smaller objects such as asteroids and comets.
• The solar system is part of a galaxy.
• galaxy a collection of stars, dust, and gas bound together by
gravity
• The galaxy in which the solar system resides is called the
Milky Way galaxy.
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.
• The radiation is composed of traveling waves of electric
and magnetic fields that have fixed wavelengths and
therefore fixed frequencies.
Studying Space
Section 1
Studying Space
Section 1
26.1 board questions
1/8/2014
Answer in complete sentences. You do
not have to copy the question. Same
paper as yesterday’s board questions.
1. Why do scientists study space?
2. How many years ago did the universe
begin?
3. What are the two units for measuring
distance in space?
4. What is the longest wavelength humans can
see?
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 orange and
red.
• Electromagnetic radiation shorter than wavelengths of violet or
longer than wavelengths of red light cannot be seen by
humans.
– Can’t see shorter than violet or longer than red
• 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
Studying Space
Section 1
Observing Space, continued
Invisible Electromagnetic Radiation
• In 1800, the scientist William Herschel
discovered infrared, which means “below the
red.”
– Infrared= below the red  longer than red
• Infrared is electromagnetic radiation that has
waves longer than those of visible light.
Studying Space
Section 1
• The ultraviolet wavelengths, which are invisible to
humans, are shorter than the wavelengths of violet light.
• Ultraviolet means “beyond the violet.”
– Ultraviolet= beyond the violet  shorter than violet
• The X-ray wavelengths are shorter than the ultraviolet
wavelengths. The shortest wavelengths are the gammaray wavelengths.
– Shortest to longest:
• Gamma ray x-ray  UV  visible light
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.
– Galileo built first telescope
• telescope an instrument that collects electromagnetic
radiation from the sky and concentrates it for better
observation
• Telescopes that collect only visible light are called optical
telescopes.
– Refracting and reflecting
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
• refraction -The bending of light
• Refracting telescopes have an objective lens
that bends light that passes through the lens and
focuses the light to be magnified by an eyepiece.
Studying Space
Section 1
Problems with refracting telescopes
• the lens focuses different colors of
light at different distances causing the
image to distort.
• it is difficult to make very large lenses
of the required strength and clarity.
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.
• Unlike refracting telescopes, mirrors in reflecting
telescopes can be made very large without affecting the
quality of the image.
Studying Space
Section 1
Telescopes, continued
The diagram below shows refracting and reflecting
telescopes.
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.
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
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
• The Hubble Space Telescope collects electromagnetic
radiation from objects in space.
• 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.
• 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.
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 electronics.
• Even medical equipment, like the heart pump, have been
improved based on NASA’s research on the flow of fluids
through rockets.