1. Astronomy

2. Astronomy
Study of objects in space such as the Sun, stars, planets, comets, gas, & galaxies.
*Also, the Earth’s place in the universe.
Universe = everything that exists

3. How long is one full revolution?
Our revolution and rotation is determined by how close or how far we are from the sun
In astronaut terms, this is determined by the astronomical unit
-1 A.U. is the distance from Earth to the Sun
-The Earth, like all planets, orbits (revolves around) the sun
How long is one full revolution?
days =
1 year
Go back and make easier to read.

4. DAY NIGHT The Earth rotates on its axis 1 full rotation = one day
warmer
NIGHT
cooler

5. Earth’s axis is not straight
Earth’s axis is tilted 23.5° from vertical
23.5° tilt

6. The Earth’s orbit actually looks like this
This shows orbit

7. Earth’s Seasons = caused by the tilted axis (23.5o)
Equinox = equal hours of daylight & darkness
Solstice = longest day & shortest day
Fall
Sep. 21
SUN
Dec. 21
Jun. 21
(shortest day)
(longest day)
Mar. 21
Spring

8. The angle of the sun’s radiation hitting the Earth impacts the climate or temperature.

9. EXAMPLE!
warmer
cooler

10. If the tilt were the only factor, then every location on Earth would have one season and it would never change.

11. When northern hemisphere is facing the sun:
•Summer Solstice June 21st or 22nd

12. SUMMER SOLSTICE Most direct rays over Northern Hemisphere
Striking at Tropic of Cancer 23.5° N
Light = 15 hours (about (NC) Dark = 9 hours

13. Antarctica is completely dark for 24 hours and the Arctic is completely light for 24 hours!!!

14. Fall Equinox (September 22 or 23)

15. Direct rays over Equator:
EQUAL amounts of daylight and darkness everywhere.
Direct rays over Equator:
Light = 12 hours Dark = 12 hours

16. Winter Solstice - December 21-22
SHORTEST DAY !!!
Most direct rays over Southern hemisphere •Striking at Tropic of Capricorn 23.5°S
Light = 9 hours Dark = 15 hours

18. Spring Equinox (March 21 or 22)

19. Direct rays over Equator:
EQUAL amounts of daylight and darkness everywhere.
Direct rays over Equator:
Light = 12 hours Dark = 12 hours

20. The Southern Hemisphere has opposite Seasons than us . . . WHY?

21. Big Bang Theory
At one time, the universe was a dense, hot, supermassive ball.
About 13.7 billion years ago, a violent explosion occurred sending material in all directions into space.

22. 1. The Beginning- An Explosion
14 billion years ago a tightly packed, very dense, high temperature singularity exploded.
The Big Bang

23. Universe Galaxies Cosmic Size Solar systems Stars
Star clusters & Constellations
Solar systems
Stars
Planets, moons
Asteroids, meteors, meteorites, comets
The “Big Dipper” constellation is a pattern made of 7 stars
watch this!
Powers of Ten Video

24. Geo-centric Helio-centric
Earth-centered
view of universe
Sun-centered
view of solar system
C. Ptolomy
90-168
N. Copernicus
modern view of the solar system:
“the Sun” is a star
planets orbit the Sun

25. Galaxies = groups of billions of stars
there are more than 100 billion galaxies
they all have different shapes
Spiral
Elliptical
Irregular

27. A cloud of space dust or gas.
Nebula
A cloud of space dust or gas.

28. Nebular Hypothesis cloud of mostly hydrogen & helium A.
A. nebula A.
cloud of mostly hydrogen & helium B.
Started rotating & collapsing toward center because of gravity forming an accretion disk , also the Sun forms C.
rocky & metallic materials form as nebula cools D.
collisions of particles created asteroid-sized objects (protoplanets or planetesmals) E.
Sun = most dense object, nuclear fusion
Rock / Terrestrial planets = more dense, heavy material, closer orbit
Gas / Jovian planets = least dense, lighter material, farther orbit
B. accretion disk
C. cooling
D. protoplanets
E. solar system

29. How the Solar System Form Summary
Solar nebula collapsed.
The nebula became denser and denser and the attraction between the particles increased.
Due to the increase collisions the center of the cloud became very hot.
The cloud flattened out into a rotating disk in which all of the planets still follow this rotation.

30. The Birth of a Star
At the same time the planets were forming material kept pulling in toward the center of the nebula.
Eventually temperature got so hot that fusion reaction began to occur between hydrogen atoms creating helium.
Fusion reactions released large amounts of pressure balancing the inward pull of gravity.

31. The Birth of a Star
As the gases became balanced, stabilization occurred, giving birth to a new star.
The Sun

32. Energy Nuclear Fission Nuclear Fusion
The splitting of an atom to create energy
Produced in nuclear reactors
The fusion of two atoms to create energy
Happens within stars

33. The Expanding Universe
1929 – Edwin Hubble found that the universe is expanding
Proof comes from Red Shifts: meaning wavelengths of light from other Galaxies are becoming longer and redder
This proves these galaxies are moving Away from us

34. Doppler Effect

35. Support for the Big Bang Theory
Cosmic background radiation
Radio signals coming from every direction in space.
Believed to be created by the big bang explosion.

36. The Earth in the Universe
The Motion of our Home. . .

37. Earth’s Motions Rotation Revolution
spinning of Earth from west to east on an axis
results in day / night
Earth makes one rotation in 24 hours
Revolution
Earth moves around the sun every 365¼ days

38. Earth’s Motions Precession
The change in direction of the northern axis
North star is different
This will change the stars near the pole but will not change the seasons (as long as the angle of the tilt, 23.5 in the case of Earth, stays the same)

39. 22.2 The Earth–Moon–Sun System
Motions of Earth
22.2 The Earth–Moon–Sun System
 Precession
• Precession traces out a cone over a period of 26,000 years.
 Earth–Sun Motion
• The solar system speeds in the direction of the star Vega.
• The sun revolves around the galaxy.
• Earth is presently approaching one of its nearest galactic neighbors, the Great Galaxy in Andromeda.

40. 3. Precession Precession- the change in the Earth’s rotational axis
As we rotate (dashed lines), the axis rotates
Add video showing precession

41. Nutation Slight wobble, or change, in Earth’s axis from 23.5°
Very slow movement due to the gravity of the moon

42. Earth’s Motions Winter – closest to the sun
Summer – farthest from the sun

43. 22.2 The Earth–Moon–Sun System
Motions of the Earth–Moon System
22.2 The Earth–Moon–Sun System
 Phases of the Moon
• The phases of the moon are the progression of changes in the moon’s appearance during the month.
• Lunar phases are a result of the motion of the moon and the sunlight that is reflected from its surface.

44. Phases of the Moon
Makes no sense without caption in book

45. 22.2 The Earth–Moon–Sun System
Motions of the Earth–Moon System
22.2 The Earth–Moon–Sun System
 Lunar Motions
• The synodic month is based on the cycle of the moon’s phases. It lasts 29 1/2 days.
• The sidereal month is the true period of the moon’s revolution around Earth. It lasts 27 1/3 days.

46. 22.2 The Earth–Moon–Sun System
Motions of the Earth–Moon System
22.2 The Earth–Moon–Sun System
 Lunar Motions
• The difference of two days between the synodic and sidereal cycles is due to the Earth–moon system also moving in an orbit around the sun.
• The moon’s period of rotation about its axis and its revolution around Earth are the same, 27 1/3 days. It causes the same lunar hemisphere to always face Earth.

47. Lunar Eclipses Occurs during full moon phases
Do not see the moon because the Earth blocks light
Sun, Earth, moon in a line

48. Solar Eclipses Occurs when sun is blocked by the moon Sun, moon, Earth
If the moon is partially blocking the sun, a partial solar eclipse will occur

49. Results of the Earth’s Motions
Other rare events include seeing other planets cross across the face of the Sun (like Venus did on June 5th, 2012, only time until 2117).

50. Results of the Earth’s Motions
Tides- As the moon orbits the Earth we experience high and low tides as the Moon’s gravity pulls on the Earth
High Tides happens when the Moon is straight above (and on the opposite side of Earth as well) and the water is pulled up by the Moon’s gravity.

51. Equatorial Bulge The Earth is not completely round
There is a bulge at the equator because of rotation
Video Link

52. Barycenter The point between two objects where they balance each other
The actual center of our solar system
The sun orbits around this point
Barycenter Video
Music :)

53. Kepler’s Laws 1st Law: orbital paths are ellipses (ovals)
Sun is at one focal point
Animation of Laws

54. Kepler’s Laws
2nd Law:
a planet sweeps out equal areas in equal times

55. Planet moves FASTER in orbit when CLOSE to the SUN, and SLOWER in orbit when FAR FROM the SUN
WHY?
GRAVITATIONAL PULL

56. The closer a planet is to the sun, the FASTER it orbits around it!!
Kepler’s 3rd Law
The further the planet is from the Sun, the LONGER it will take for the planet to orbit the Sun.
The closer a planet is to the sun, the FASTER it orbits around it!!
Mercury – 88 days
Venus – 225 days
Mars – 687 days
Jupiter – 4331 days
Pluto – 90,582 days or 248 years!!

57. Kepler’s Laws 3rd Law: T2 = d3 T= time of orbit
d = distance (avg) from the sun