Astronomy 1 Notes: The Universe

1. ASTRONOMY 1
The Universe
ppt by Robin D. Seamon
HOOK VIDEO: Cosmos #31

2. 2
STUDYING SPACE
VOCABULARY:
Big Bang Theory
Nebular Hypothesis
Ptolemy
Copernicus
Galileo Galilei
geocentric
heliocentric
theory

3. Studying Space
HISTORY
PTOLEMY
•Worked with sundials & trigonometry
•astronomer who accepted the common
idea that the planets & Sun traveled around the
Earth! (geocentric view)
•Had planets moving in perfect, circular orbits
3
WRONG!!!

4. COPERNICUS (1473-1543)
•Proposed that the Earth & other planets
revolved around the sun (heliocentric view)
•Had planets moving in perfect, circular orbits
•People did NOT like this idea!
4

5. GALILEO GALILEI (1564-1642)
•Used the invention of the telescope &
mathematics to look at the universe
•Observed The Milky Way, the moon, Jupiter’s
moons & more
5http://ml.shapiro.gs/?p=64http://www.wwnorton.com/college/engli
sh/nael/18century/topic_3/illustrations/i
mtelescope.htm

6. UNIVERSE ORIGINS
Big Bang Theory
-scientific theory on the origin of the universe
-Universe began as a small, hot, super-dense
superforce (singularity)
-13.7 billion years ago it expanded rapidly (“Big
Bang”)
-atoms -> nebulas -> stars & galaxies
-still expanding & cooling today
Nebular Hypothesis-
Solar systems & bodies are made from clouds of
gas.
6

7. 7
https://www.quora.com/Can-someone-explain-to-me-the-big-bang-theory

8. 8
What is a Theory?
NOT a guess!
Theory: the way scientists interpret facts based
upon repeatedly tested observations of the
scientific method; can be proven or rejected like
a hypothesis if new discoveries are found
https://study.com/academy/lesson/hypothesis-theory-law-in-science.html

9. 9
Regarding the origins of the Universe:
-We can’t go back in time so we have to look for
clues we can observe today
-Today we use Mathematical formulas & models
to provide supporting evidence.

10. 10
https://socratic.org/questions/how-does-the-red-shift-of-distant-
galaxies-indicate-that-the-universe-is-expandi
Big Bang EVIDENCE
1. Expansion & cooling of the Universe as seen
in the redshift of far away galaxies:
Doppler shift that is observed when far away
objects move away from the observer. Light is
perceived to be closer to the red end of the light
spectrum the farther away the object moves.
Faster movement causes more redshift.
LONGEST WAVESSHORTEST WAVES

11. 11
https://socratic.org/questions/how-does-the-red-shift-of-distant-
galaxies-indicate-that-the-universe-is-expandi
Big Bang EVIDENCE
2. Abundance of more light chemical elements
in the Universe.
(Created first = more of them)
Hydrogen
Helium
Deuterium
lithium

12. 12
https://www.space.com/25126-big-bang-theory.html
Big Bang EVIDENCE
3. Cosmic background radiation:
the “echo of the explosion” in the form of
radiation that can be measured today at the
farthest (oldest) parts of the Universe.

13. 13
OUR ADDRESS
VOCABULARY:
Universe Kuiper Belt
Galaxy Oort Cloud
Star terrestrial planets
Constellation Jovian planets
Solar system
Satellite
Planet
Asteroid
Comet
Meteorite
planetesimal

14. Universe
• All existing matter and space; the cosmos
• Comprised of smaller units… 14

15. Each of these specks of light is a galaxy!
Galaxy
• A system of millions or billions of stars, gas,&
dust held together by gravity
https://science.nasa.gov/astrophysics/focus-areas/what-are-galaxies
15

16. There are 3 main types of galaxies:
Elliptical
Oval-shaped disk
Irregular
No shape
Our galaxy, The Milky
Way is a spiral galaxy.
Spiral
Spiral disk with arms
16

17. http://en.es-static.us/upl/2011/01/Milky_Way_face-on_edge-on.jpeg
17
Our Galaxy

18. https://www.space.com/19915-milky-way-galaxy.html
We can take a look through one of the arms
of our Milky Way on a Winter’s night. 18
Our Galaxy

19. The Big Dipper
Constellation
• A group of stars that appear to form a pattern
19

20. 20

21. Planet: a celestial body that orbits a star, large
enough to have removed debris from its orbit
Solar System
• A group of planets, moons, asteroids, comets
and meteoroids, surrounding a central star
https://science.nasa.gov/astrophysics/focus-areas/what-are-galaxies
21

22. Terrestrial Planets: rocky bodies; closest to the sun
Mercury Venus Earth Mars
Jovian Planets: huge gas planets
Jupiter Saturn Uranus Neptune
https://https://en.wikipedia.org/wiki/Solar_System
22
Our Solar System

23. Size Comparison
https://https://en.wikipedia.org/wiki/Solar_System
23
Our Solar System

24. Star- very large burning ball of gas
SUN
https://scienceforthekids.wordpress.com/2013/04/10/what-is-the-sun/
24
Our Star

25. Distance Comparison
http://www.astronomy.com/magazine/ask-astro/2018/04/the-oort-clouds-icy-bodies
25
Asteroid belt- between Mars & Jupiter; source of
asteroids
• large, irregularly shaped object orbiting the
Sun)
Our Solar System

26. Distance Comparison
http://www.astronomy.com/magazine/ask-astro/2018/04/the-oort-clouds-icy-bodies
26
Kuiper Belt- disk-shaped; ice & icy rock; source of
comets
• ice/dust object orbiting the
Sun; releases a tail of gas
when it warms passing by
the sun
Our Solar System

27. Distance Comparison
http://www.astronomy.com/magazine/ask-astro/2018/04/the-oort-clouds-icy-bodies
27
Oort Cloud- spherical shell of icy
planetesimals
• A minute planet that isn’t
large enough to be
spherical
Our Solar System

28. Earth
https://www.nasa.gov/content/goddard/earth-from-space-15-amazing-things-in-15-years/
28
Our Planet
LINK: Blue Beauty- click through

29. Satellite: smaller body orbiting a larger body in
space; a moon
https://www.nasa.gov/content/goddard/earth-from-space-15-amazing-things-in-15-years/
29
Our Satellite
Luna

30. 30

31. 31
MOTION
VOCABULARY:
Johannes Kepler precession
Sir Isaac Newton nutation
axis barycenter
orbit solar year
latitude equinox
longitude solstice
Rotation waxing
Shape waning
Sidereal day lunar eclipse
Solar day solar eclipse
seasons high/ low tide
Revolution spring tide
Leap Year neap tide

32. http://www.sciencekids.co.nz/sciencef
acts/scientists/johanneskepler.html
http://kepler.nasa.gov/johannes/#anchor784359
JOHANNES KEPLER: (1600)
Mathematician & astronomer
Kepler’s laws of motion:
1. objects travel in an ellipse
around another object
(focal point); faster when
closest to the sun

33. http://www.sciencekids.co.nz/sciencef
acts/scientists/johanneskepler.html
http://kepler.nasa.gov/johannes/#anchor784359
JOHANNES KEPLER: (1600)
Mathematician & astronomer
2. A line segment joining a planet
and the Sun sweeps out equal
areas during equal intervals of
time

34. http://www.sciencekids.co.nz/sciencef
acts/scientists/johanneskepler.html
VIDEO: Planetary
orbits are Eliptical
JOHANNES KEPLER: (1600)
Mathematician & astronomer
3. the more distant from the
sun an object is, the longer it
takes to orbit (larger orbit, slower
speed)
P = orbital period
T = semi-major axis of its orbit

35. Tyco Brahe (1546/1601)
Mathematician & astronomer
• Made the most precise
observations to date of the
celestial heavens WITHOUT a
telescope
• Not a proponent of the
Copernican system
35

36. http://www.mrdowling.
com/601-newton.html
SIR ISAAC NEWTON: (1643-1727)
Mathematician & astronomer
Newton’s Laws of Motion
1. objects remain still or in motion until
another force is applied to it
(law of inertia)
2. acceleration happens when a force is acted on
an object. The greater the mass of the object, the
more force is needed to move it. (f=ma)
3. for every action, there is an equal and opposite
reaction

37. 37
Barycenter- point between two objects where
they balance each other as they orbit

38. 38

39. 39
• When one of the bodies is significantly larger
than the other, the point will be below the
surface of the larger object:
• EARTH & MOON: barycenter is below Earth’s
surface
• Causes a ‘wobble’

40. 40
MOTION VOCABULARY:
• Axis: The tilt on which the earth spins
(rotates)
• Latitude: lines running on a map or
globe
• Longitude: lines running on a map or
globe

41. LATITUDE:
Measured N & S
of the Equator
LONGITUDE:
Measured E & W
of the Prime
Meridian
http://www.polaris.iastate.edu/NorthStar/Unit2/unit2_sub1.htm
BACK
A
X
I
S
http://pseudoastro.wordpress.com/2009/01/30/planet-x-
and-2012-proof-earth-is-not-experiencing-a-pole-shift/

42. 42
MOTION VOCABULARY:
• Rotation: spinning around from one point &
back on an axis; causes night & day
• Orbit: the path one body follows around
another body
• Revolution: the movement of a body in orbit
from one point back to that point; one
complete trip; referred to as a solar year

43. http://www.incois.gov.in/Tutor/science+society/lectures/illustrations/lecture7/daylength.html
Solar Day:
Time it takes for Earth to rotate on its axis so that
the Sun appears in the same position in the sky.
Earth solar Day ~ 24 hours.
Sidereal Day:
Time it takes for Earth to rotate so that a distant
star appears in the same position in the sky
Earth sidereal Day ~ 23 hours 56 minutes

44. 44
http://www.incois.gov.in/Tutor/science+society/lectures/illustrations/lecture7/daylength.html

45. http://xwalk.ca/360vs365.html
Solar Year
The earth travels one revolution around
the sun
365 ¼ Earth days.
Leap Year
Every four years, we add the fractional days
into a whole day (Feb 29) giving that calendar
year 366 days.

46. 46
Why do we have seasons?
It’s a combination of:
1. Earth’s tilt on its axis
2. Earth’s position in its solar revolution

47. Axis tilt

48. 48
Summer Solstice
Winter Solstice
Autumn Equinox
Spring Equinox
•Equinox: when the sun is directly above
the equator
•Solstice: when the sun is farthest N & S
of the Equator
Summer Solstice

49. Longer days in the
Summer
Summer Solstice Equinoxes Winter Solstice
Shorter days in the
Winter
Day &
night are
almost
equal
Longest
day
Shortest
day
http://www.uwm.edu/~kahl/CoVis/Seasons/

50. Why does the moon
change?

51. •Luna rotates on its axis in about 27.3 Earth
days
•Luna revolves around the Earth in about 28
Earth days
(Therefore, we see the same FACE of the
moon)

52. Luna’s Phases:
VOCABULARY
• Waxing the appearance of the moon getting larger
(more sunlight shining on it as nights go by)
• Waning the appearance of the moon getting smaller
(less sunlight shining on it as nights go by
• Crescent
• Gibbous
crescent
gibbous

53. Waxing
crescent
Waning
crescent
VIDEO: V IDEO: Same Side of the Moon

54. Earth’s shadow on moon during lunar eclipse
Shadow on moon during solar eclipse
Eclipse: the shadow of one celestial body falling
on another body
Solar eclipse
Lunar eclipse

55. TIDES
Moon’s gravity pulls on the Earth’s
oceans, causing the level of water to
rise or lower:
1. High tide
2. Low tide
http://www.fotonomy.com/Ceterus
Paribus/photo/1ee2edd8/

56. 1.Spring tides:
Largest daily range
-during new & full
moons; every 14
days
2. Neap tides:
Smaller daily range
-during 1st & 3rd
quarters of moon
(sun, Earth, moon align)
(sun & moon are at right angles to the Earth)
VIDEO: Tides