1. Astronomy

2. Earth’s Rotation Rotation – the spinning of Earth on its own axis.
Responsible for us having day and night.
The Sun rises in the east and sets in the west, as do the Moon, planets, and stars as a result of Earth’s rotation.
One Earth rotation equals a day, but actually only takes 23 hr 56 min.

3. Earth’s Precession
Precession is a gravity-induced, slow and continuous change in the orientation of Earth’s rotational axis that takes years to come to completion.
Changes the view of the stars from the poles, but doesn’t affect the seasons.

4. Earth’s Nutation
In addition to causing tides, the moon’s orbit around Earth also causes the Earth to nod, or bob throughout its rotational period, called nutation
Occurs over an 18 year period, changes the direction of Earth’s tilt by less than a ½ degreee. This only very slightly increases or decreases the amount of seasonal effects.

5. Nutation
The main cause is the gravitational torque of the Moon, Sun, and the planets.

6. Earth’s Equatorial Bulge
The Earth has an equatorial bulge of km ( miles) due to its constant rotation.
That is, its diameter measured across the equatorial plane ( km, 7,927 miles) is km more than that measured between the poles ( km, 7,900 miles).
Objects located on the equator are about 21 kilometers (13 miles) further away from the center of mass of the Earth than at the poles and thus the gravitational force at the equator is less ( m/s²)

7. Revolution of Earth
Revolution-time it takes for an object to complete its orbit around another object.
Takes the Earth approximately 365 days to revolve around the sun.
In combination with tilt of Earth’s axis, revolution is responsible for annual changes in length of days and temperature variations

8. The tilt of Earth’s axis is the reason for seasons.
Earth’s axis tilted to the ecliptic (plane in which Earth revolves around Sun) at 23.5 degrees
The Earth’s tilt is most directly responsible for the seasons that we see every year
More direct sunlight leads to warmer temperatures, which is why summer is experience in our hemisphere when Earth is tilted towards the Sun.
During winter, our hemisphere is tilted away from the sun, allowing there to be less direct sunlight and therefore colder temperatures.

9. Solstice
Summer solstice-Sun is at highest altitude in the sky (June 21); number of daylight hours at maximum
Winter solstice-Sun is at lowest altitude in the sky (Dec 21);number of daylight hours at minimum
Seasonal Flash

10. Equinox
Two positions Earth is not pointed at Sun; as result both hemispheres receive same amount of sunlight and Sun is directly overhead at the equator.
Reason for milder temperatures in spring and fall is because neither hemisphere is pointed towards the Sun.
Called autumnal and vernal equinox (equinox means “equal nights”)
Seasonal Flash

11. The Sun’s Structure

12. Solar Flares
A solar flare is a sudden, rapid release of charged particles from the Sun, often associated with intense brightness.

13. Solar Prominence
A solar prominence is an arc of gas that erupts from the surface of the Sun and held above its surface by strong magnetic fields and can last for months.

14. Solar Spots
A sun spot is a dark area of reduced surface temperature on the Sun caused by intense magnetic activity.

15. Solar Winds
A solar wind is a constant stream of energized, charged particles, primarily electrons and protons, flowing outward from the Sun.
Earth is protected from solar winds by its magnetic field.

16. The Sun’s Facts & Figures
Age: 4.6 billion years
Composition: 92.1% Hydrogen, 7.8% Helium
Rotation Period at Equator: 26.8 days
Rotation Period at Poles: 36 days (decreases with latitude)
Mean Distance to Earth: 92,956,000 miles

17. The Sun’s Facts & Figures
99.8% of the mass of the entire solar system
Surface Temperature: 5,500 degrees Celsius (10,000 degrees Fahrenheit)
Core Temperature: 15 million degrees Celsius (27 million degrees Fahrenheit)
Orbited by 8 planets and at least one dwarf planet

18. The Sun’s Facts & Figures
Energy: 100 billion tons of dynamite per second
One of more than 100 billion stars in the Milky Way
It orbits some 25,000 light years from the galactic core, completing a revolution once every million years or so.
The sun has enough nuclear fuel to stay much as it is now for another 5 billion years.

19. The Sun’s Facts & Figures
Radius: 432,169 miles which is x greater than Earth’s
Equatorial Circumference: 2,715, 396 miles compared to Earth’s 24,874 miles
Volume: 338,102,469,632,763,000 cubic miles compared to Earth’s 1,301,019 cubic miles
Mass: 4,385,214,857,119,400,000,000,000,000,000 lbs which is 333,060,402 x greater than Earth’s

20. The Sun’s Facts & Figures
Surface Area: 2,347,017,636,988 square mile compared to Earth’s 11,917,607 square miles
Surface Gravity: m/s2 which is 28 x greater than Earth’s gravity
Escape Velocity: 1,381,756 mph which is 55 x greater than Earth’s

21. Why is the Sun important?
Supports most life on earth by providing warmth required for survival (exception: underwater hydrothermal vent ecosystems)
Allows plants to grow via photosynthesis which in turn absorb carbon dioxide and create oxygen

22. How does the Sun produce light and heat?
Deep in the sun's core, nuclear fusion reactions convert 2 hydrogen atoms to 1 helium atom, which produces an extreme amount of energy.
The energy is transferred to Earth via radiation
How does the Sun produce light and heat?

23. Speed of Light
It travels at an incredible 300,000 kilometers (186,000 miles) per second.
If you could travel at the speed of light, you would be able to circle the Earth’s equator about times in just one second!
All electromagnetic waves travels at the speed of light.
It takes one photon of light about 8 minutes and 18 seconds to travel from the Sun to the Earth

24. Forms of Energy Released by Sun
All forms of electromagnetic energy, excluding gamma rays are produced by the Sun. (X rays,ultraviolet, visible light, microwaves, radio waves, infrared)
Higher frequency forms of energy, such as X Rays and UV rays, are filtered out by our atmosphere.

25. Moon Phases The moon does not emit light, it only reflects sunlight
Half the moon’s surface is always reflecting light; however, we may not always see all of the lit surface.
The amount seen we see is referred to as a moon phase

27. Moon’s Relation to Ocean Tides
The Moon revolves around the Earth just as the Earth revolves around the Sun.
The Moon’s gravity pulls on Earth along an imaginary line connecting Earth and the Moon, creating bulges of ocean water.
When the Sun and Moon are aligned, the result is higher-than-normal tides, called spring tides.
When the Moon is at a right angle to the Sun-Earth line, the result is lower-than-normal tides, called neap tides.

28. Ocean Tides

29. 10:32 a.m.
Bay of Fundy
5:24 p.m.

30. Solar & Lunar Eclipses
What type of moon occurs during a full solar eclipse?
What type of moon occurs during a full lunar eclipse?

31. Which is a solar eclipse and which is a lunar eclipse?
Solar or Lunar Eclipse?
Which is a solar eclipse and which is a lunar eclipse?

32. Hierarchy of the Universe-Listed top to bottom, largest to smallest
Universe-all existing matter
Consists of
Galaxies-made of many stars
Some stars in the galaxy might have
Planetary systems-planets and other objects orbiting a star
Such as our solar system in which our
Planet, Earth, revolves around the Sun

33. Our Solar System

34. The Milky Way

35. Kepler’s Work
Tycho Brahe led a team which collected data on the position of the planets ( with no telescopes).
Mathematician Johannes Kepler was hired by Brahe to analyze the data.
He took 20 years of data on position and relative distance.
No calculus, no graph paper, no log tables.
Both Ptolemy and Copernicus were wrong.
He determined 3 laws of planetary motion ( ).

36. Kepler’s Three Laws
The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The Law of Ellipses)
An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of Equal Areas)
The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of Harmonies)

37. Kepler’s First Law

38. Kepler’s Second Law

39. Kepler’s Third Law

40. Relationship of Barycenter to Planetary Orbit
Isaac Newton also determined each planet orbits a point between it and the Sun called the barycenter
The barycenter is the balance point between two orbiting bodies (where all the mass of an object is concentrated)
If one of two bodies orbiting each other is more massive than the other, the center of mass is closer to the more massive body
If two bodies are similar in mass, their center of mass is near the middle position between them
For any planet and the Sun, the center of mass is just above the surface of the Sun (or within the Sun) because the Sun is more massive than any planet

41. Barycenter and Sun’s Motion
Our Sun stays relatively in the same position in relation to the planets of our solar system, but the Sun is not stationary.
It moves as the planets tugs on it, causing it to orbit the solar system’s barycenter.
The Sun never strays too far from the solar system barycenter, considering most of the solar system’s mass is in the Sun.
Flash

42. Barycenter The Sun-Earth barycenter is near to the center of the Sun.
The Earth-Moon barycenter is close to the edge of the Earth.
The Sun-Earth barycenter is near to the center of the Sun.

43. The Universe Is In Constant Motion
Just as Earth revolves around the Sun, our solar system revolves around the central point of our Milky Way galaxy.
All solar systems in a galaxy are rotating around the galaxy’s central point.

44. The Proposed Beginning of the Universe
Scientist have proposed that the universe began as an infinitely hot and infinitely dense speck of matter (singularity) that rapidly expanded outward to form all the matter that makes up our universe.
This matter eventually combined to create all the planets, stars, and other objects in the universe.
Universe is still expanding as it was at the time of the proposed “big bang”, just at a slower rate.

45. The Big Bang Theory The universe must have had a beginning
The redshift of distant galaxies means that the Universe is probably expanding.
Very early in its history, the whole Universe was very hot. As it expanded, this heat left behind a "glow" that fills the entire Universe. The Cosmic Microwave Background, which has been accurately measured by orbiting detectors, is the afterglow.
The observed abundance of hydrogen, helium, deuterium, and lithium in the universe.

46. The Doppler Effect
Spectral lines are shifted in wavelength by motion between the source of light and the observer due to the Doppler Effect.
The Doppler Effect is "the change in the frequency of a wave observed at a receiver whenever the source or the receiver is moving relative to each other or to the carrier of the wave, the medium" (McGraw-Hill).
Sound waves are stretched, increasing wavelength, decreasing frequency = lower pitch.
Sound waves are squeezed, decreasing wavelength and increasing frequency = high pitch.

47. Redshift
If a star is moving toward the observer, the spectral lines are shifted toward shorter wavelengths, or blueshifted. The light from the object will appear bluish.
If the star is moving away, the wavelengths become longer, or redshifted. The light from the object will appear reddish.
Redshift Video

49. Star Formation
Stage 1- Stars are born in a region of high density Nebula, and condenses into a huge globule of gas and dust and contracts under its own gravity.
Stage 2 - A region of condensing matter will begin to heat up and start to glow forming Protostars. If a protostar contains enough matter the central temperature reaches 15 million degrees centigrade.
Stage 3 - At this temperature, nuclear reactions in which hydrogen fuses to form helium can start.
Stage 4 - The star begins to release energy, stopping it from contracting even more and causes it to shine. It is now a Main Sequence Star.

50. Hertzsprung-Russell Luminosity
 The Sun will eventually move upwards and to the right, into the realm of the red giants. Then it will move up and to the left, and then drop straight down into the graveyard of white dwarfs.

51. Planet Formation
Upon Earth’s initial formation, remnants of matter floating in the vacuum of space began to collide with one another, creating a spinning motion.
As more and more gas and debris came together around this one central spinning area, the gravitational pull of this object increased.
This increase in gravitational pull continued to attract more and more matter, becoming larger. When it gets big enough, the gravity was strong enough to attract gaseous materials and form an atmosphere. Gravity Simulation
This is essentially how planets were formed.

52. Why does the Earth revolve around the Sun?
Earth would continue moving in a straight line if not for its proximity to the Sun.
The Sun’s gravitational pull, which is extremely greater than ours due to the Sun’s mass, keeps our planet and all the other planets in our solar system in orbit.