Transcript Astronomy Chapter Nineteen: Galaxies and the Universe • 19.1 Tools of Astronomers • 19.2 Stars • 19.3 Galaxies and the Universe.

Astronomy
Chapter Nineteen: Galaxies and
the Universe
• 19.1 Tools of Astronomers
• 19.2 Stars
• 19.3 Galaxies and the Universe
Investigation 19A
Tools of Astronomy
• How does a telescope work?
19.1 Tools of Astronomers
• An astronomer is a
scientist who studies
objects in space.
• The universe is
defined as
everything that
exists, including all
matter and energy.
19.1 Writing very large numbers
• Scientific notation
is a mathematical
abbreviation for
writing very large
(or very small)
numbers.
How do scientists write
the number 150,000,000?
19.1 Units of distance in space
•
•
Astronomers have
developed units other
than kilometers or
meters to measure the
vast distances in
space.
One light year is equal
to the distance that light
travels through space
in one year.
19.1 Studying the universe
• A galaxy is a huge
collection of gas,
dust, and billions of
stars.
• Our galaxy, the Milky
Way, contains
billions of stars!
19.1 Studying the universe
• Light from other
galaxies and stars
takes time to reach
Earth.
• The farther away the
object they are
viewing, the further
back in time
astronomers are
looking.
19.1 Telescopes
• A telescope is a
device that makes
objects that are far
away appear closer.
• In the 1600s, Galileo
was the first to use a
telescope for viewing
the night sky.
19.1 Telescopes
• Telescopes work by collecting the light from
a distant object with a lens or mirror and
bringing that light into a concentrated point,
called the focal point.
19.1 Telescopes
• A refracting telescope uses lenses to bend, or
refract, light, making objects look bigger.
• Refracting telescopes are made from a long tube,
a glass objective lens that you point toward the
sky, and an eyepiece lens.
19.1 Telescopes
• A reflecting telescope uses
mirrors instead of lenses to
gather and focus light.
• A concave mirror (called the
primary mirror) is placed at
the back of a tube.
• The secondary mirror
deflects the light to an
eyepiece lens.
19.1 Other types of telescopes
•
Astronomers use different types of telescopes to
view the different types of waves emitted by
objects in space.
1. A radio telescope works like an extremely powerful
receiver that picks up radio waves from space.
2. In 1983, the Infrared Astronomical Satellite (IRAS)
was launched to map the entire sky at infrared
wavelengths.
3. X-ray telescopes are designed to detect high-energy
radiation (X-rays) from space.
19.1 Other types of telescopes
• These three images of the Crab Nebula
were taken with different telescopes.
• Each new view gives astronomers more
information.