Download File - Flipped Out Science with Mrs. Thomas!

Unit Overview:
Understanding the Universe
S TA R T ING WIT H E A R T H A ND B E YO ND
Our solar system – examining size
and scale in space
6.11B UNDERSTAND THAT GRAVITY IS THE FORCE THAT
GOVERNS MOTION IN OUR SOLAR SYSTEM
8.8 D MODEL AND DESCRIBE HOW LIGHT YEARS ARE USED
TO MEASURE DISTANCES AND SIZES IN THE UNIVERSE
Why do the planets revolve around the Sun?
• Define gravity: Any object with mass exerts a force of
attraction on other objects with mass.
• The Earth, Sun and planets are not the only objects that
exert gravity. Everything with mass exerts a force a gravity
including us!
• Our mass is very small relative to the mass of the Earth and
so the force of attraction we exert on the objects around us
is very small; too small to overcome friction.
• The Sun exerts a large force of gravity because it is so
massive and that is what keeps the planets in orbit around it.
Solar system in the Milky Way galaxy
The Milky Way
• The Milky Way is a cluster of stars, known
as a galaxy
• It contains hundreds of billions of stars
• If you traveled at the speed of light for
about 2 million years, you would reach
the next galaxy – the Andromeda Galaxy
• There are billions of galaxies in the
universe and they are VERY far apart
from each other!
Distance in Space
• A light-year is how astronomers
measure distance in space. It’s defined
by how far a beam of light travels in one
year – a distance of six trillion miles.
• Astronomers use light-years and
astronomical units to measure distance
• To repeat - A light-year is the distance
that light travels in one year
Light Years Explained
To put it in perspective…
• Have you ever been on your way to meet some friends and,
while en route, called to tell them you’re running late?
• If you’re like me, you might tell them “I’m about ten
minutes away”. You’re using how long it will take you to get
there as a substitute for how far away you are.
• Astronomers do the same thing when figuring out the
distance to a star or galaxy, but instead of relying on how
fast they could drive or walk, they use a beam of light as
their reference.
How long does it take light to get from the Sun to
the Earth?
• A light beam needs only
8 minutes to travel the
93 million miles (150
million kilometers) from
the sun to the Earth.
• Traveling at that speed,
you would encircle the
globe of Earth almost
eight times in one
second.
Distances to other places
• Impressive! Certainly faster than traveling by airplane. So if you were to
travel off the Earth in a straight line at light speed, you’d get pretty far in
the same amount of time, right?
• Actually, since space is so vast, you wouldn’t have even made it to the
moon. Travel to the moon takes about a second-and-a-half, at light speed.
• Travel to the sun at light speed takes about eight minutes. Can you even
imagine?
• Traveling at a speed where you cross nearly 200,000 miles every second for
eight full minutes would only get you to the center of our solar system.
• The fact that light takes time to get anywhere has an interesting side
effect. If light from the sun takes eight minutes to get to us, then we’re
actually seeing the sun as it was eight minutes ago. We’re looking into the
past!
How about even larger distances? The Milky Way
Galaxy is about 100,000 light years across, we are about
26,000 light years away from the center of it.
Powersof10.com
Even further - Our closest neighbor
• Moving beyond our galaxy, it’s just over two million light years to our
nearest galactic neighbor, the Andromeda galaxy. The light we currently
see from that galaxy left there about the same time the ancestors of
modern humans were first discovering stone tools.
Astronomers measure the distance to
the Andromeda galaxy using lightyears.
One light-year equals about 6 trillion
miles. This galaxy is over 2 million
light-years from Earth
Another measurement in space: Astronomical Unit
• The distance of the Sun to the Earth is called an Astronomical
Unit (AU) and is sometimes used to denote large distances that
are less than a light year
• Distances within our universe are measured in light years and
AU

A light year = about 63,241
astronomical units
Sun to Earth Distance
1 Astronomical
Unit (AU)
93,000,000 Miles
• The Sun is at an average distance of about 93,000,000 miles (150 million
kilometers) away from Earth.
• Like all of the other planets in our Solar System, Earth does not travel around
the Sun in a perfect circle. Instead its orbit is elliptical.
• This means that the distance between Earth and the Sun changes during a
year.
• At its closest, the Sun is 91.4 million miles and at its farthest, the Sun is 94.5
million miles (152.1 million km) away.
• The Earth is closest to the Sun during winter in the northern hemisphere.
Other planet distances in astronomical units
(from the sun to that planet)
Body
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
AU
.39
.72
1.0
1.5
5.2
9.5
19.2
30.1
39.5
What do you
notice about
the table?
What number
is Earth?
WHY?
Check for understanding: #1
• If the nearest star is 4 light years away
how many miles away is it?
A light year means 6 trillion miles.
Think about that for a moment. If you go outside tonight
and shine a flash light at the sky, in the next year that
light will travel 6 trillion miles.
6 trillion x 4 light years = 24 trillion miles!
Check for understanding: question 2
• How long will it take for the light from
that star (that is 4 light years away) to
travel to the Earth?
Four years.
Remember, a light year is the distance
that light can travel IN A YEAR!
Light Year and Time
• Using a light year as a distance measurement has another
advantage -- it helps you determine age.
• Let's say that a star is 1 million light years away. The light from that
star has traveled at the speed of light to reach us. Therefore, it has
taken the star's light 1 million years to get here, and the light we
are seeing was created 1 million years ago.
• So the star we are seeing is really how the star looked a million
years ago, not how it looks today. In the same way, our sun is 8 or
so light minutes away. If the sun were to suddenly explode right
now, we wouldn't know about it for eight minutes because that is
how long it would take for the light of the explosion to get here.
Origin of the Universe
8 . 8 D – MO DE L A ND D E S CR IB E HO W L I G HT Y E A R S A R E U S E D TO
ME A SURE DISTA NCES A ND S I Z E S I N T HE U NI VE R SE
How the universe began
• What evidence supports scientific theories on
the origin of the universe?
• Video: The beginning of everything (6 min)
Scientific Theories about the Beginning:
• Astronomers combine mathematical models with
observations to develop workable theories of how the
Universe came to be.
• The mathematical underpinnings of the Big Bang
theory include Albert Einstein's general theory of
relativity along with standard theories of fundamental
particles such as quantum mechanics.
• Today NASA spacecraft such as the Hubble Space
Telescope and the Spitzer Space Telescope continue
measuring the expansion of the Universe.
• One of the goals has long been to decide whether the
Universe will expand forever, or whether it will
someday stop, turn around, and collapse in a "Big
Crunch?"
Big Bang Theory
• Once it was understood that the Universe had a beginning, scientists
began to ask “how did it come into existence, and what existed
before it?”
• Most scientists now believe that the answer to the first part of the
question is that the Universe sprang into existence from a singularity - a term physicists use to describe regions of space that defy the laws
of physics. We know very little about singularities, but we believe that
others probably exist in the cores of black holes.
• The second part of the question, as to what existed before the Big
Bang, has scientists baffled. By definition, nothing existed prior to the
beginning, but that fact creates more questions than answers. For
instance, if nothing existed prior to the Big Bang, what caused the
singularity to be created in the first place?
The growing universe:
• Once the singularity was created (however it happened), it began
to expand through a process called inflation. The Universe went
from very small, very dense, and very hot to the cool expanse that
we see today.
• This theory is now referred to as the Big Bang, a term first coined
by Fred Hoyle during a British Broadcasting Corporation (BBC)
radio broadcast in 1950.
• Interestingly, there really wasn’t any sort of explosion (or bang) as
the name suggests, but rather the rapid expansion of space and
time.
• It is like blowing up a balloon, as you blow air in, the exterior of the
balloon expands outward.
Evidence Gathered from the Hubble Telescope
• The Hubble Space Telescope is one of the most powerful and prolific science
instruments ever made, earning a place as one of the technical wonders of the
modern world. From its lofty perch 350 miles above Earth, Hubble sees farther
and sharper than any previous telescope.
• By witnessing bursts of light from faraway exploding stars, Hubble helped
astronomers discover dark energy, which pervades our universe. This
mysterious energy exerts a repulsive force that works against gravity.
• One of Hubble’s key duties was to help astronomers determine a precise age
for the universe. The telescope’s keen vision helped astronomers accomplish
that goal by measuring the brightness of dozens of pulsating stars
• By knowing their brightness, astronomers then calculated the stars’ distance
from Earth.
• Astronomers determined the universe’s age - it is about 13.75 billion years old.
Famous
Hubble
Images
Famous
Hubble
Images
Famous
Hubble
Images
Famous
Hubble
Images
HW Assignment:
• Read pages 328-332 in your textbook on evidence of the big bang
theory
• Then watch this video: “The Beginning of Everything” (posted on my
website)
• You will go to the google form also posted and answer the questions.