Astronomy Class PPT for NC 2014

1.  You will receive a list of unit vocabulary at the top of
every unit note packet!
 How you choose to complete the vocabulary is up to
you!
 It should be completed in your science notebook or
stored in your binder and will be checked for
completion on the day it is due. [10 points]
 Expect a vocabulary test approximately 1 week after
you receive the list.

2. Unit 1
The study of stars and space.
Big Bang

3. • The universe is expanding
o How do we know this?
• In the late 1920’s, Edwin Hubble
discovered that All galaxies were “red-shifted”
when viewed from Earth.
• This meant that all galaxies were moving
away from Earth and each other, and thus,
the universe must be expanding.
• Learn to annotate!

4. • All matter and energy in the universe was once
condensed into a single point
• 13.8 bya
• Moments after the Big Bang, the universe was very
hot and dense
o Protons, neutrons, and electrons formed
o Hydrogen formed
o There was enough energy to start nuclear fusion
 Helium formed

5. • Evidence
o Background radiation
 Space is...space!
o There should be no heat at all (0K)
o Scientists have measured space; 3K (Background
radiation exists)
o Composition of matter in the universe
 74% hydrogen
 24% helium
Expansion of the Universe

6. A. Electromagnetic Energy
1. The sun is the major energy
source for weather changes in
the atmosphere and many of the
changes occurring at Earth’s
surface.
2. Energy from the sun comes in
many different wavelengths.

8.  Each element or
compound in its
gaseous form
produce a unique
set of spectral
lines.
 Spectral lines act as
“FINGERPRINTS”
as they identify
elements present in
the
STARS/GALAXIES
.
Example: The SUN has thousands of dark lines &
more than 60 elements have been identified by
matching these lines with those elements known on
Earth!

9. • The Doppler Effect
o The change in frequency of a wave an observer relative to its motion
o Moving toward you: Waves are
compressed together
o Moving away: Waves are stretched

11. • Redshift
o When the light of a distant object (star,
planet, etc.) is viewed through a prism,
the spectrum is not continuous
o Black lines appear: Absorption lines
 Determine which elements are present
o When the object is moving away from
us, the absorption lines are shifted
toward the red end of the spectrum
(stretched): Redshift!

12. Using the spectroscope, astronomers can determine
whether a particular object is moving toward Earth or
away from Earth

13. • Our sun is just one of billions of stars in the Milky
Way galaxy.
• Only star whose surface we can study.
• Through spectroscopic analysis of the sun, scientists
know that most of the known elements are found in
the sun
o Hydrogen makes up 74%of the sun’s mass
o Helium makes up 24%

14. • Sunspots: “Dark” areas
on the sun
o “Cool” areas
o The magnetic field
breaks through the
surface, causing a
disruption in heat
transfer
o The number of
sunspots varies every
11 years. This is known
as the solar cycle.

15. • The core
o Nuclear fusion

16. Life Cycles of Stars

17. • A Star is Born

18. • A star’s “life cycle” can last billions of years.
• The following slides describe the general phases in
stellar evolution

19. Nebula
• Dark, cool clouds of
interstellar gas and
dust.
• Often referred to as
“stellar nurseries.”
• Stars begin to form
as gas and dust
collide.

20. Protostar
• Developing star
• Not yet hot enough
for fusion reactions
(10x106 K)
http://seethaler.net/space/protostar.jpeg

21. Main Sequence Star
• Hydrogen to Helium
fusion has begun!
• The hotter, larger
stars burn H2
fastest.
• This stage makes
up 90% of a star’s
“life.”
http://content4.bestthinking.com/s/1/topics/500/images/3e6daf0-40a3-495c-8006-5da9e7e9b069_972.jpeg

22. Earth’s Place in the Universe

23. Universe
Our Milky Way
Galaxy is one of
billions of galaxies in
an expanding
universe

24. Milky Way Galaxy
• Our Sun/solar
system is one of
an estimated
180 billion stars
making up this
spiral galaxy

25. Our Solar System
Earth – a small dense rocky planet, one of 8 planets
that orbit the sun
AND – the only one we know of that has LIFE as
we know it……

26. So…. What Keeps Us Going?
Newton’s Laws of Gravity
Gravity and Inertia

28. Newton’s Law of Inertia
States that a body in forward motion will continue in forward
motion unless acted on by an outside force.
Inertia
Gravity
Stable Orbit

29.  Inertia – causes a
planet to move in a
straight line.
 Gravity – pulls a
planet toward the
sun.

30. Rotation
• The spinning of a
celestial body (Earth)
on an imaginary axis

31. Rotation
A. Earth’s Direction of Rotation:
WEST to EAST
2. Angular Rate of Rotation:
THINK – one complete rotation
360 degrees
24 hours
Rate = 3600/24 hours = 150/hour

32. B. Effects of Earth’s Rotation
1. Day and Night

33. B. Effects of Earth’s Rotation
2. Apparent daily motion
of the sun
a. Earth rotates from
WEST to EAST
b. Sun “appears” to move in
an arc from EAST to
WEST

34. Earth is NOT a perfect sphere.
It is an oblate spheroid –
slightly wider across the
equator (due to its rotational
spin)
Earth‘s axis is not stable. It
moves/wobbles (like a top).
This is known as precession.
It’s very slow - 26,000 years to
complete one cycle.
Within the precession are
additional motions known as
nutations. These are
smaller motions back and forth
as the precession occurs.

35. V. Revolution
• The orbiting of one celestial body around another
celestial body.
A. Earth’s Angular Rate of Revolution
1. 360 degrees
2. 365 days
3. Rate = 3600/365 days ~ = 10/day

36. B. Effects of Earth’s
Revolution
1. Nighttime constellations
change in a yearly cycle.
2. Constellation – groups
of stars that form
patterns of imaginary
things such as animals,
legendary heroes, and
mythological gods

37. 3. Seasons – a yearly cycle

38. 5. Seasons of the Year
A. Causes:
1. Revolution - Earth revolves around the sun
2. TILT - Earth is tilted/inclined on axis 23 1/2o
3. Parallelism of Axis - Earth’s axis always points in the
same direction.

39. B. Earth’s axis is tilted 23.50 relative to the plane
of it’s orbit.
• Draw and label
your diagram
according to the
diagram at the
right. Be sure to
name the
equator, the
Tropic of Cancer
and Capricorn
and note where
we live.

40. C. The apparent path of the sun changes with the
seasons and with latitude.
N.C. 35.5 degrees North Latitude

41. D. Length of Daylight (duration of daylight) –
changes with seasons and with latitude.

42. E. Factors affecting Insolation
1. Shape of the Earth (spherical)
2. As latitude
increases, the
angle of
insolation
decreases, and
the intensity of
insolation
decreases.

43. C. Season of the Year
a. As Earth travels along its orbital path around the sun,
the angle of insolation at a given latitude changes with
the seasons. This depends on how far a given latitude
is from the direct rays of the sun. The direct rays
migrate between the Tropic of Cancer (north) and
the Tropic of Capricorn (south).

44. 4. Time of Day
a. The angle of
insolation
changes in the
course of one
day. Maximum
intensity occurs at
Noon.

45. b. Looking South
• The shadow of a vertical pole indicates how the angle of insolation
changes during the day. The higher/greater the angle of insolation,
the shorter the shadow, and the greater the intensity of
insolation.

46. VI The Moon
A.The moon is a natural
satellite of Earth.

47. B. Physical Properties of the Moon
1. Size
a. Diameter: 2160
miles
b. Compared to Earth
Diameter of Moon = 2160 = 1
Earth 8000 4
2. Gravity
a. 1/6 the gravity of Earth
b. This is because the Moon
has – less mass

48. 2. Atmosphere
a) The Moon has No atmosphere,
so radiation from sun strong
b) Gravity too weak so gases
escape into space.
c) Without an atmosphere radiation
from the sun is INTENSE!
d) Frozen water may exist at the
Moon’s polar regions, but none
in liquid form

49. 3. Phases of the Moon -
Period of Revolution = 1 month OR 29.5 days
a. The phases of the moon are caused by the moon’s
revolution around Earth.
b. Our Earth view of the changing illuminated part of the
moon’s surface that face’s Earth.

50. c. Waning moon - the decrease
in light (on the left), away
from being a full moon to new
moon, is called a.

51. d. waxing moon - as the moon
increases towards becoming
a full moon.

53. 4. Moon Rotation
b. Does that mean the
moon doesn't
rotate?
c. YES it does --one
rotation for each
revolution around
Earth!

54. 5. Lunar Eclipse
a. An eclipse of the Moon can only take place
at full moon and only if the Moon passes
through some portion of the earth’s
shadow. The shadow is actually composed
of two (2) cone-shaped components, one
inside the other. The outer or penumbra
shadow is a zone where some portion of
the sun’s rays are blocked. In contrast, the
inner or umbra shadow is a region devoid
of all direct sunlight.

55. 6. Solar Eclipse
a. A solar eclipse
occurs when the
moon passes
directly between
the Earth and
sun.
b. New Moon are
the only time
solar eclipses can
occur.

56. 10. Tides
a. Tides are the alternate
rising and falling of the
sea.
b. This is caused by the
Moon’s gravitational pull.
c. The rising of tides is
affected by the position and
distance of moon!
d. The period from high tide to
high tide is 12 hours and 12
minutes.
e. Tides are a CYCLIC
change.