Name____________________ Astronomy The Big Picture Astronomy is the study of and , or everything The fancy word for everything used by astronomers is The universe is literally defined as So… everything that is, and has happened, and will happen is included in that one word Considering the size of the universe is very difficult The universe is theoretically It is expanding than the speed of light The best guess we have is that the universe is old Evidence for the age of the universe ( ) There should be no temperature in space, but there is The oldest energy we can detect has been traveling for years, so the universe must be at least years old
Transcript
Name____________________
AstronomyThe Big PictureAstronomy is the study of and , or everything
The fancy word for everything used by astronomers is
The universe is literally defined as
So… everything that is, and has happened, and will happen is included in that one word
Considering the size of the universe is very difficult
The universe is theoretically
It is expanding than the speed of light
The best guess we have is that the universe is old
Evidence for the age of the universe ( )
There should be no temperature in space, but there is
The oldest energy we can detect has been traveling for
years, so the universe must be
at least years old
The Big Bang Theory
Many scientists believe that the universe was once an infinitely ,
collection of mass
This mass suddenly started to we call this like a balloon
It is still expanding today
Scientists know that the universe is expanding because of the “ “ of light from
distant galaxies
Redshift is an example of the
The Doppler Effect is an apparent change in ___________________ as an object
towards or away from an observer
This applies to waves
As the source of the waves moves
an observer
waves are
As the source of the waves moves
an observer
waves are
Stars emit primarily energy
There are different _______________________ of energy in the universe.
The Electromagnetic Spectrum shows us this. (ESRT p. ___)
Longer wavelengths are on the shorter wavelengths on the
Longer wavelengths = energy
Shorter wavelengths = energy
The relatively small section of visible light is the light our can detect
. . . . . . .
Of the colors we can see, has the longest wavelength and has
the shortest
We can tell the composition of distant stars by
their
When white light is viewed through a
prism it is broken into the visible spectrum
Different elements
different wavelengths of energy causing
in the
spectrum, like a fingerprint
So, by analyzing the spectrum of a star we can determine the elements present in the
atmosphere
Each element should block out a specific
When a star is moving from us the spectral lines get shifted towards the
end of the spectrum, thus
If a star is moving us spectral lines get shifted to the end
It’s not actually that things are flying away from us
causing the redshift
It’s that as light travels towards us, the space it is
traveling over is stretching causing an increase
in wavelength
For space’s expansion to cause this shift it must be
expanding faster than the speed of light,
otherwise wavelength would remain the same
, or very nearly all, the stars that have been analyzed are
This means is moving away from us
But it isn’t actually that everything is moving away from us, it’s that everything is moving
away from else
The further away from us something is, the its redshift
Thus the universe must be
So, if the universe is expanding, it must have been in the past
If you carry that idea to its maximum, you reach the infinitely small, hot, dense point from
which physicists believe the universe started
And when the universe started expanding it was a “ ” bang
Earth’s Address
The part of the universe we can see we call the
Mass in the observable universe seems to be grouped into local
We are in the supercluster
The supercluster is split into clusters (groups of galaxies)
Galaxies are clusters of billions of , , and black holes, and other
stuff
Our galaxy is called the
On a clear night you can see it as a brighter band across
the sky
There are clusters of stars scattered throughout galaxies
called a solar
These are the stars that are relatively close to us
In one such solar interstellar neighborhood we find our
Our solar system includes our , planets with various moons, the asteroid
belt, and the Kuiper belt
But, we will primarily be focusing on the 4th largest planet in our solar system, Earth
So, to put things in order from smallest to biggest: We are on …
- in the
- in the
- in the
- in the
-
This is similar to when you give an address
We are in the town of Sanborn, in the
state of New York, in the country called the
U.S.A., on the continent called North
America, in the northern hemisphere of the planet Earth…
Milky Way Galaxy
A galaxy is a collection of stars and other stuff held together by
There are many shapes galaxies can take
Our galaxy is a galaxy
Our solar system is located in one of the arms, about
light years from the center
Sol (Our Solar System)
Our sun is a
We call it Sol or the sun
Orbiting Sol are
planets with their moons
An Belt
The
Belt- dwarf planets including
Pluto
We have two types of planets
Terrestrial planets
-
-
-
Jovian Planets (gas giants)
-
-
-
Between and is the asteroid belt
A collection of that never grouped together to form a
Too far away to get pulled into Jupiter, but pulled to hard by its gravity to stick
together
Beyond Neptune is the Kuiper belt
A collection of dwarf planets and comets
Asteroids
Comets
Belt-
comets
Dwarf Planet
Star
Belt
Planets:Rocky, smaller, and more dense.
Planets:
Gaseous, bigger,
and less
Stars
Nebula-
Particles start to stick together due to
Once enough mass has accumulated
pulls particles together
Once enough pressure accumulates
spontaneous
begins
This is when the star is born
powers stars
Two nuclei , or fuse, to form a new
A lot of energy is released
This is how our sun is creating
Two hydrogen atoms combine to form a helium atom and
release radiation
H + H = He + energy
When a star runs out of a certain element it starts to use different elements and enters
a new
This means it changes size, and usually color
Nearly every element on the periodic table was created by a star
Exceptions/Weirdness
Hydrogen- one proton, one electron, has always existed
Anything heavier than Iron (Fe) was created by a
Most elements above 103 were created in a lab by scientists
Evolution of stars
ESRT Pg.
H-R (Hertzsprung Russel) Diagram
Not a of stars
Plot of stars by brightness (
) and in
degrees Kelvin
Early Stage
stars
Stars fusing into
helium
Include our sun
Intermediate Stages
Giants or Supergiants
Once a star has used all its hydrogen it starts to fuse into other
elements releasing more energy
This causes the star to
It becomes much , and more
Once the star has used up the atoms that can be fused, the outward force will collapse,
as will the star
Late Stage
If the star is massive enough, then it will explode into a forming a
If the star is not that massive, it will fade into a
If the star exceeds a certain mass it will turn into a , pulling light into it
with everything else
Earth Motions
There are two primary motions we are interested in for this unit
Traveling
another body
The Earth follows a
orbit (revolution) around the
sun
How many degrees per day does
the Earth move around the sun?
360° in days =
The Earth spins around the
north and south poles on its axis
The axis is tilted from the solar plane
The Earth’s axis is thought to have started
perpendicular to the solar plane but was tilted by
a gigantic with an object nearly
the size of mars
This collision
- the axis
- the planet
-Blasted material into space that eventually became our
The Earth rotates from West to East ( )
This causes everything to appear to move across the sky from to
The Earth rotates 360° in 24 hours or, 15°/h
The further you are from the poles the faster you move as the Earth rotates
All the planets are rotating
Oddities
Venus is the only planet to rotate clockwise, and that is because it has been flipped
nearly 180°
The axis of Uranus has been rotated about 98° from the solar plane, likely from
hitting a large asteroid
Evidence
Star Trails- all the stars in the sky appear to move around , the north star
Polaris is located directly above the
How fast to the stars move across the sky?
Rotation of the Earth causes
of wind, ocean currents,
airplanes etc.
Paths are deflected ( ) to the
in the northern
hemisphere, in the
southern hemisphere
Pendulum
Leon Foucault was doing an experiment in 1851 with
a pendulum and noticed that it
direction if he let it swing freely for an extended
period of time
The direction of the pendulum swings appears to
change direction over the course of the day due to
the of the Earth
Day and Night
The sun appears to move across the sky every day because your location on the Earth
is into and out of darkness
Constellations
of stars that form a
Imaginary things such as animals, legendary heroes, gods, myths, the zodiac, etc.
Different constellations are visible in the night sky at different times of
because the Earth around the sun
Your birth-sign comes from the constellation that the sun is in at noon on the
day of your birth
Celestial Sphere
Imaginary sphere with at its center
Models what we see from the surface of the planet as it through space
We use this to how things will appear to an observer at different places on
the planet at different times of year
In reality we know that the objects in space are mostly not moving around us
We are moving relative to them, making them to go around us
We didn’t always think this way
Models of the Universe
model
Since we are on the surface of the earth we cannot see the
motion of the Earth
This led to early astronomers thinking that everything
moved the Earth
Things in Gods creation would naturally move in
perfect
Some objects in this model seem to stop and move
backwards across the sky
We call this motion
The ancient Greeks called these objects “wanderers”
or, in Greek, “ ”
To deal with retrograde motion astronomers added circles in each orbit, making
things very complex, but also accurate
The geocentric model was accepted for almost 1400 years because it explained
celestial observations
model
First proposed by Nicolaus Copernicus in
There was no reason for there to be loops in the
planetary orbits
Stated that the was in the center and
everything revolved around the sun in
This model, for a time, was actually more inaccurate
than the highly complex geocentric model
Stars remain in the background
Neither of these models were entirely correct
Careful measurements revealed that the Earth was actually away from
the sun at certain times of year so…
The planets do revolve around the sun in perfect circles
The orbits are , they form a shape called an
The sun is not located at the exact center of a planets orbit, but on one of the
A. Seasons1. There are 3 reasons why we have a change in seasons
throughout the year on Earth:a. Because the Earth ______________ around the Sun.b. Because the axis of the Earth is ______________.c. Because the axis of the Earth always points in the
same ___________________.
2. Because the Earth is tilted it receives different amounts of ___________________ at different latitudes.
a. Insolation is _______________ __________________________.
b. Insolation hits the Earth at different angles and intensities.
3. Angle of the Sun throughout the year in NYS.
4. Where is the Earth located in its orbit during these times of year?
24.5º 48º 71.
5º
a. Name of Day: Winter Solstice
Latitude of Sun’s direct rays:
__________________________
This is the path the Sun takes across the sky during the winter solstice. Notice the sun is ___________ in the sky and the path is short. We have less daylight during the winter, right?
Sunrise direction:________ Sunset direction:_________ Duration of insolation: ________Angle of Sun in NYS: ________
b. Name of Day: Spring (Vernal) Equinox
43°N
Winter Solstice
Latitude of Sun’s direct rays:
__________________________
This is the path the Sun takes across the sky during the spring equinox. On this day there is equal day and night- 12 hours of daylight and 12 hours of darkness EVERYWHERE on Earth.
Sunrise direction:________ Sunset direction:_________ Duration of insolation: ________
43° NSpring
Equin
Angle of Sun in NYS: ________c. Name of Day: Summer Solstice
Latitude of Sun’s direct rays:
__________________________
This is the path the Sun takes in the sky on the summer solstice. This is the _______________________ the sun will get in NYS. Notice how long the path of the sun is on this day. Don’t we have more daylight during the summer?
43°N
Summer Solstice
Sunrise direction:________ Sunset direction:_________ Duration of insolation: ________Angle of Sun in NYS: ________
d. Name of Day: Fall (Autumnal)Equinox
Latitude of Sun’s direct rays: _________________________
This is the path the Sun takes across the sky during the fall equinox. On this day there is equal day and night- 12 hours of daylight and 12 hours of darkness EVERYWHERE on Earth.
43° NFall Equ
inox
Sunrise direction:________ Sunset direction:_________ Duration of insolation: ________Angle of Sun in NYS: ________
5. It doesn’t matter what time of year it is, you ALWAYS need to look ___________ to see the noontime sun.
Zenith- point in the sky directly
___________the observer.
Eccentricity
A measure of how an orbit (path) is around the sun
Represented by a number that is always a decimal rounded to the nearest
( )
Formula
Eccentricity =
There is label for eccentricity (this is the only one)
Practice:
Find the Eccentricity of the following shapes
Dots =
Line through both dots =
What happens to the foci as eccentricity decreases?
What happens to the shape as the eccentricity decreases?
Does it become more or less round?
Conclusion
As the eccentricity approaches 1, the orbit becomes circular
As the eccentricity approaches 0, the orbit becomes circular
The eccentricity for each planet in our solar system, and Earth’s moon is listed on ESRT
page
What is different about the moon’s orbit as opposed to the planets’?
Since the Earth’s orbit is (an ellipse) there is a time of year when we are
closer to the sun, and a time when we are further away
What seasons are the Earth in at aphelion and perihelion according to the diagram?
- where Earth is furthest from the sun
- where the Earth is closest to the sun
When Earth is closer to the sun the gravitational attraction is
Remember, gravity is a function of
Larger distance = lower force
This causes the Earth to in its orbit when it is closer to the
sun
Remember, Earth moves faster when it is closer to the sun so…
Do planets that are further away from the sun take longer to travel around it?
The Moon
Formation
The
states that the Earth collided with a very, very
large object
About the size of
That collision melted both objects, and
material from both
This material eventually formed the moon
The moon is Earth’s only
It orbits earth traveling in an orbit
E = 0.055
The Earth is located within the orbit at one of the
This also means that, just like the Earth/Sun, the moon is closer to the Earth once every
The moon is about a ( ) the
size of the Earth
3.7 moons would be the same size as the Earth
Because the moon is smaller than the Earth it has
less pull
You would less on the moon
Remember that weight is a measurement of the force of on , not
actually a measurement of how much of you there is
You will often see diagrams where the Earth and Moon are not to scale
Remember, if you make a diagram, divide the Earth into , the moon should fit
inside one
Because of the moon’s lower gravity, it has no
Gravity on the moon is not strong enough to trap gas particles
Without atmosphere on the moon the sun’s is very strong
This is why spacesuits are so bulky
If exposed you would get a sunburn in a matter of
seconds
The moon is covered in
Craters are bowl shaped depressions formed as a
result of impacts
Why does the Moon have so many more than Earth?
The moon has no atmosphere
Meteors impacting Earth tend to burn to ash in the upper
due to
This is what causes “shooting stars”
This is also why the end of Apollo 13 is so tense. If the astronauts got the angle
wrong they would literally burn up upon entering the atmosphere
There is also no water on the moon, so there is no weathering or erosion to
rock formations
is the breakdown of rocks
Think dissolving sugar or salt in a glass of water
is the movement of pieces of rock
Think landslides, dirt in streams, etc.
It takes the moon days to revolve 360° around the Earth
We usually simplify this and say it takes month
The moon also on its axis at the speed
It rotates 360° in days
This means we only ever see side of the moon from Earth
We didn’t know what the other side of the moon looked like until we sent people into
space
Thus the “dark” side of the moon
It isn’t always dark, we just can’t see it
So, if we can only see one side of the moon, why does it go through “phases”
We see different phases because the moon around the Earth
It constantly changes its position relative to the Earth and the sun
Important Side note
The moon does not “shine” like the sun, it does not produce its own light
It merely reflects light from the sun
Phases
Moon phases are caused by the
of the moon around the Earth
There are two terms used to describe the
change in moon phases
- when the moon
gets brighter between New Moon and Full
Moon
- When the moon gets darker between Full Moon and New Moon
Diagrams are usually drawn with the view as though you were out in space, looking down at
the Earth and Moon
When determining phases follow these steps
1- Figure out where the sun is
2-Determine the appropriate perspective
If you are on the Earth looking at the moon, turn your paper so the Earth is between
you and the moon
If you are looking from the moon to the Earth turn your paper so the moon is between
you and the Earth
3- Block out the half of the moon you would not be able to see from Earth
4- Figure out what part of the moon should be illuminated (bright) and which part should
be dark
5- Re-orient your paper and shade the appropriate part of the circle
Seeing moon phases is all about perspective. Pretend you are on the Earth looking toward the moon at its different positions (turn your paper).
Moon Phases as seen from Earth
a-
b-
c-
d-
e-
f-
g- Then back to…
What type of relationship is h-
represented by the regular
change in phase of the moon?
ab
cd
gh
So, if the moon revolves all the way around the Earth in 27.3 days how long does it take to
go through one cycle?
days…. Why?
As the moon is revolving around the Earth, the Earth is around the
sun, so the moon has to travel a little bit further to get back between the Earth and Sun
This is much closer to one month
In other words
The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle (from new Moon to
new Moon) is 29.5 days. The Moon spends the extra 2.2 days "catching up" because
Earth travels about 45 million miles around the Sun during the time the Moon completes
one orbit around Earth.
Eclipses
There are two types of eclipses
They are named for the object being blocked…
eclipse is when the shadow of the Earth passes over the moon
eclipse is when the moon blocks the sun, or the shadow of the moon
passes over the Earth
Shadows
How much larger is the sun than the Earth?
Sun’s diameter – km
Earth’s diameter – km
times bigger
Volume
1,300,000 Earths would fit inside the sun
Because the sun is so much larger and, because the sun is generating light, the shadows of
planets are not straight or continuous forever
They are shaped
- The fully dark part of the shadow
- the partial shadow
Lunar eclipse
When the shadow of the passes over the
What phase is the moon in during a lunar eclipse
Solar Eclipse
Occurs when the passes between the and sun, briefly covering it
up
Since the moon is so much smaller than the Earth, only a small area of the planet will
actually see a solar eclipse
What phase is the moon in when this occurs?
Types of Eclipses
Why don’t we have a solar eclipse and a lunar eclipse every month?
The orbital plane of the moon is 5° above the solar plane
Tides
Tides are a rising and falling of oceans and other large bodies of water
They are caused by the gravitational force exerted on Earth by the , and the
The change of tidal height is due to the Earth’s and the
of the moon
Recall that gravity is a force applied by objects possessing mass
The closer you are to the object, the the force
The side of the Earth in line with the
moon experiences
tide because the water is being pulled
towards the moon
Similarly, a high tide occurs on the
opposite side of the planet because
the Earth is being pulled towards
the moon with more force than the water on the opposite side of the planet
There are two categories of tide based on the orientation of the sun and moon
