Transcript Explain. How is Copernicus`s description of the system of planets

Warm up
• People usually say that the sun rises in
the east, moves across the sky, and sets
in the west. Is this description literally
correct? Explain.
• How is Copernicus's description of the
system of planets different from
Ptolemy's description?
The Solar System
Brahe and Kepler
• Brahe observed the positions of the
planets for about 20 years
• Kepler had discovered that the orbit of
each planet is an ellipse
Inertia and Gravity
• Newton concluded that two factors—inertia
and gravity—combine to keep the planets in
orbit.
• Inertia-the tendency of a moving object to
continue in a straight line or a stationary
object to remain in place.
• Gravity- attracts all objects toward one
another. The strength of gravity depends
on the masses of the objects and the
distance between them
The Sun
•The sun's energy comes from nuclear fusion
•In the process of nuclear fusion, hydrogen atoms
join together to form helium. occurs only under
conditions of extremely high temperature and
pressure
The Sun's Atmosphere
•The sun's
atmosphere has
three layers: the
photosphere, the
chromosphere, and
the corona
The Inner Planets
•The four inner planets are small and have rocky
surfaces
The Outer Planets
•The first four outer planets—Jupiter,
Saturn, Uranus, and Neptune—are
much larger than Earth, and do not
have solid surfaces.
Comets, Asteroids, and Meteors
• Comets are chunks of ice and dust whose
orbits are usually very long, narrow ellipses
• asteroids, are too small and too
numerous to be considered fullfledged planets. Most asteroids
revolve around the sun between
the orbits of Mars and Jupiter
• meteoroid is a chunk of rock or dust in
space. Meteoroids usually come from
comets or asteroids
Rockets and Satellites
• A rocket moves forward when gases
expelled from the rear of the rocket push
it in the opposite direction
• Satellites and space stations are used for
communications, navigation, collecting
weather data, and research.
Phases, Eclipses, and Tides
• The positions of the moon, Earth, and
the sun cause the phases of the moon,
eclipses, and tides.
• The moon revolves around Earth and
rotates on its own axis.
• It takes the moon about 27.3 days to
revolve around Earth.
• When the moon's shadow hits Earth or
Earth's shadow hits the moon, an eclipse
occurs
• solar eclipse occurs when the moon passes
between Earth and the sun, blocking the
sunlight from reaching Earth
• A lunar eclipse occurs at a full moon when
Earth is directly between the moon and
the sun
• As Earth rotates, the moon's gravity
pulls water toward the point on Earth's
surface closest to the moon.
The Structure and Origin of the Moon
• This diameter is only one fourth Earth's
diameter. The moon's average density is about
the same as the density of Earth's outer
layers
• The theory of the moon's origin that best fits
the evidence is called the collision theory.
• Material from the object and Earth's outer
layers was thrown into orbit around Earth.
• Eventually, this material combined to form the
moon.
Galaxies
• Astronomers have classified most galaxies into
three main categories: spiral galaxies, elliptical
galaxies, and irregular galaxies.
• Spiral Galaxies Photo A shows a galaxy that has
the shape of twin spirals, called a spiral galaxy.
These views show that spiral galaxies have arms
that spiral outward, like pinwheels.
• Not all galaxies have spiral arms. Elliptical galaxies
look like flattened balls. So elliptical galaxies
contain only old stars.
• Irregular Galaxies Some galaxies do not have
regular shapes. The Large Magellanic Cloud is an
irregular galaxy about 160,000 light-years away
from our galaxy.