Transcript Galaxies and Stars

GALAXIES AND STARS
8.E.4A.1 Obtain and communicate information to model the position of the Sun in
the universe, the shapes and composition of galaxies, and the measurement unit
needed to identify star and galaxy locations
GALAXIES
 Galaxies are made up of gas, dust, and billions of stars
 Galaxies have different shapes
 Elliptical
 Spherical or flattened disks
 Spiral
 A nucleus of bright stars and 2 or more spiral arms
 Irregular
 No definite shape
 Shapes of Galaxies can change over time as a result of collisions with
other galaxies and evolution of galaxies themselves
THE SUN AND THE MILKY WAY
 The Sun is a star in the Milky Way galaxy
 Milky Way is a spiral galaxy
 The Sun is located approximately 2/3 of the way from the center of the
Milky Way
GALILEO GALILEI
 Born on February 15, 1564 in Pisa, Italy
 “Father of Modern Science”
 Modernized physics and astronomy
 Discovered all objects fall at the same rate
 Created a hydrostatic balance for measuring tiny objects
 Supported the Heliocentric Theory
 Developed a telescope of his own, used it to observe the moon’s surface
features, Venus revolved around the Sun, and Jupiter’s moons revolved
around Jupiter not the Earth providing evidence against the Geocentric
Theory
TYCHO BRAHE
 Born December 14, 1546
 Danish astronomer and alchemist
 Precise and comprehensive astronomical and planetary observations
which influenced future discoveries (Planetary Laws of Motion)
 Did not use a telescope for his astronomical observations
 Discovered the variation of the Moon’s longitude for the lunar theory
JOHANNES KEPLER
 Born December, 27, 1571
 From the Holy Roman Empire (modern day Germany)
 1596, a math teacher
 Worked with Tycho Brahe and seceded him upon Brahe’s death
 Founded the 3 Laws of Planetary Motion
 Using Brahe’s data, Kepler discovered that the orbit of Mars was an
ellipse
 Defended the Heliocentric Theory
3 LAWS OF PLANETARY MOTION
 The Orbits of the Planets are Ellipses, with the Sun
at one focus of the ellipse
 The line joining the planet to the Sun sweeps out
equal areas in equal times as the planet travels
around the ellipse
 The Ratio of the squares of the revolutionary
periods for 2 planets is equal to the ratio of the
cubes of their semimajor axes
LIGHT
 Light travels 9.46 x 1012 Km (5.88 x
1012 miles) in a year
 Light from the Sun travels 8
minutes before reaching us
 Light from the Andromeda galaxy
(closest galaxy to the Milky Way)
was emitted 2.5 million years ago
(before the first humans)
 The further away a light is, the
older the light is when we see it.
PARALLAX
 Method astronomers use to determine how far away stars are
 Stars seem to shift in position when viewed from Earth because of
Earth’s revolution around the Sun
 Parallax shift
 Astronomers use the diameter of Earth’s orbit to determine the
parallax angle across the sky
EXPANDING UNIVERSE
8.E.4A.2 Construct and analyze scientific arguments to support claims that the
universe began with a period of extreme and rapid expansion using evidence from the
composition of stars and gases and the motion of galaxies in the universe
THE UNIVERSE
 The Universe is composed of matter and energy
 All of the matter in the universe now was in the universe when it
formed
EVIDENCE
 Evidence to Support Scientist Claims
 Looking for the oldest star
 Nebula (gas and dust) exist in space and are remnants from the formation of
the universe
 Stars undergo a life cycle, amount of hydrogen gas in the star changes
therefore affecting the brightness and color of the star
 https://www.youtube.com/watch?v=8FPVIV-LzYM
 Measuring the rate of expansion of the universe
 Astronomers determined the galaxy is expanding based on the color of light
emitted from galaxies and stars
 As the Universe expands and galaxies move apart, the wavelength of light
emitted from those galaxies is stretched which shifts the light toward the red
end of the spectrum (red-shift). More distances or faint a galaxy, the more
rapidly it is moving away from Earth
 https://www.youtube.com/watch?v=o3G_eaSaLck
 https://www.youtube.com/watch?v=y5tKC3nEx2I