2. What is Astronomy? -The scientific study of the Universe beyond Earth
-Astronomy is based on observations and experiments that can be repeated, and that give the same results no matter who does the experiment or makes the observation.

3. Why do we study Astronomy ?
Natural disasters (comets, meteorite impact)
Recreation and esthetics (universe is pretty)
Scientific inquiry and curiosity
Education of an informed society (you !)
Our place in the Universe
Origin and fate of the Universe (Cosmology)
True Science versus science fiction

4. BOOM !!

5. 12 ½ light years away

6. 250 light years away

7. 5 thousand light years away

8. 50 thousand light years away

9. 500 thousand light years away

10. 5 million light years away

11. 100 million light years away

12. 1 billion light years away

13. 14 billion light years away

14. Early Astronomy Geocentric and Heliocentric Models
Geocentric Model - moon, sun, and the known planets, Mercury, Venus, Mars, and Jupiter, orbit Earth; Geo = earth
Heliocentric Model - Earth and the other planets orbit the sun; Helio = sun
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15. Early Astronomy
Nicolaus Copernicus concluded that Earth is a planet. He proposed a model of the solar system with the sun at the center.
Johannes Kepler (German) ( ) Used the planet data of Tycho Brahe and developed Kepler’s Three Laws of Planetary Motion

16. Early Astronomy Galileo Galileo
• Galileo’s most important contributions were his descriptions of the behavior of moving objects.
• He developed his own telescope and made important discoveries:
1. Four satellites, or moons, orbit Jupiter.
2. Planets are circular disks, not just points of light.
3. Venus has phases just like the moon.
4. The moon’s surface is not smooth.
5. The sun has sunspots, or dark regions.

17. Early Astronomy  Sir Isaac Newton  Universal Gravitation
• first to formulate and test the Law of Universal Gravitation.
 Universal Gravitation
• Gravitational force decreases with distance.
• The greater the mass of an object, the greater its gravitational force.

18. The Universe
 The Big Bang Theory states that at one time, the entire universe was confined to a dense, hot, supermassive ball. Then, about 13.7 billion years ago, a violent explosion occurred, hurling this material in all directions.

19. The Big Bang  Supporting Evidence
•Red shift, or a Doppler shift toward the red end of the spectrum, occurs because the light waves are “stretched,” which shows that Earth and the source are moving away from each other.
• Scientists discovered a type of energy called cosmic background radiation. Scientists think that this radiation was produced during the big bang.

24. Planetary Motion: The Earth–Moon–Sun System
• The solar system is speeding 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.

25. The Earth–Moon–Sun System
 The two main motions of Earth are rotation (turning, or spinning, of a body on its axis) and revolution (motion of a body, such as a planet or moon, along a path around some point in space).

27. Planetary Motion: Precession
Precession is a slow, slight change in direction (over 26,000 years) of the Earth’s axis, but without any change in tilt.
This movement is similar to the wobble in a spinning top.
It causes the north pole to point at different parts in the sky during the 26,000 year cycle.
Today, the North Pole points to the star Polaris (North Star).
Seasons don’t change, but stars nearby do.

28. Precession

29. Astrology is NOT Astronomy and is NOT Science
Seeks to discover “hidden knowledge” by the interpretation of omens (like reading tea leaves).
Results are not repeatable.
Predictions are vague and not testable.

32. Annual Motions: What causes Seasons?
Tilt of Earth on its axis (23.5 degrees)
What causes summer in the northern and southern regions? when that side is tilted towards the sun
What causes winter in the northern and southern regions?
when that side is tilted away from the sun
The seasons in the northern and southern regions are opposite each other because when one region is pointed towards the sun, the other region is pointed away from the sun.

37. The Earth’s Lone Satellite:
The Moon

38. Moon Facts 4.5 billion years old
The Moon is a satellite and only reflects light from the Sun. It does NOT provide any light on its own.
It is Earth’s closest neighbor in space, and it is roughly 240,000 miles from the Earth most of the time.
It has a Nickel-Core and the rocks are silicate based.
The Moon “wobbles,” a term called libration, which makes it possible for humans to see roughly 51% of the Moon’s surface. (Dark side of the moon)
The Moon has many different features, including mare (“seas” or lava-formed plains), terra (highlands), craters (created from asteroid and meteorite impacts), and mons (mountains).

39. Theories of Moon Origin
1. Nebular Contraction or Condensation Theory says the Earth and Moon were produced or created at the same time in the same or close nebulas during the creation of the Solar System.
2. Capture Theory : the Earth’s gravity pulled the Moon in while it was passing near Earth.
3. Fission Theory, in which the Moon split apart of the primordial Earth while it was forming and stayed close by due to Earth’s gravity.
4. (the one scientists lean towards) is the Collision Theory in which an asteroid or something large in size hit the primordial Earth forcing back of the remnants (orbiting clouds of debris) soon clustered together over time to become our Moon.

40. Tides
Earth’s rotation on its axis causes tides to change every 6 hours
Times of tide vary every day because the moon orbits the earth every 28 days
Spring Tides: the highest tides that occur on Earth. Occur during Full & New Moons
Neap Tides: are lower than usual, during 1st Quarter and Last Quarter phases.
Tides are the periodic rise and fall of the ocean
High tide: highest level that the water rises
side facing towards and away from the moon
Low tide: lowest point of the water
Tides are caused by the gravitational attraction of the moon, earth, and sun

44. Phases of the Moon
Over the course a month, actually 29.5 days, the Moon goes through its different phases.
Waning - lit surface of moon is getting smaller
Waxing - lit surface of moon is getting bigger
Synchronous rotation is the state where orbital and rotational periods are equal
As the moon orbits earth, the same side faces Earth at all times because the moon has a synchronous rotation, spinning exactly once each time it goes around Earth
Each phase will be shown and the day in the cycle that it appears. Please draw each phase, the day and name that is shown on the following slides.

46. Moon Phases Day 0-1 New Moon
The Moon is in front of the Sun, and the “Dark Side of the Moon” receives the Sun’s light.
Day 0-1

47. Waxing Crescent
The Moon is backlit by the Sun as it approaches one quarter of its cycle completion.
Days 2-6

48. First Quarter
One quarter of the Lunar Cycle is complete, but only HALF of the Moon is lit. (Name indicates portion of cycle completed not amount of light shown!)
Day 7.4

49. Waxing Gibbous
The Moon is getting brighter and brighter as it is approaching Full Moon and it is positioning itself across from the Sun with the Earth in the middle.
Days 8-13

50. Full Moon
The Moon is halfway through its cycle. The Moon is fully-lit by the Sun, and it is directly across from the Sun with the Earth in the middle.
Day 14.8

51. Waning Gibbous
The Moon is starting to darken again. It is over halfway through its cycle.
Days 15-21

52. Last Quarter
The Moon is now three-fourths, 75%, through its cycle. It is in its “last quarter” before the New Moon repeats.
Day 22.1

53. Waning Crescent
The Moon is almost completely dark again. Less and less light is being shown, and the Moon repositions itself between the Earth and the Sun.
Days 23-28

54. New Moon
It’s Day 29.5, and the New Moon reappears. The Cycle has officially ended and officially begins again.

56. Have you ever heard the saying…
“Once in a Blue Moon”?
That is actually a real phenomenon. During the course of a year, it is possible to have 13 Full Moons. In the case of a 13-Full-Moon year, one month has two full moons. When a month has TWO FULL MOONS, the second Full Moon is called the Blue Moon!

57. Moon  Perigee is the point at which the moon is closest to Earth.
 Apogee is the point at which the moon is farthest from Earth.

58. Total Solar Eclipse Aug. 21st, 2017 Pathway of Solar Eclipse
occurs when the moon moves in a line directly between Earth and the sun, casting a shadow on Earth.
Total Solar Eclipse Aug. 21st, 2017
Pathway of Solar Eclipse *

60. Lunar Eclipse occurs when the moon passes through Earth’s shadow.
The moon also rises and sets 50 minutes later each day because the moon has moved 13 degrees in its orbit over a 24 hour period, and Earth has to turn an additional 13 degrees for the moon to rise.
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