Basic terms, historical figures, a few concepts
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| 206487678 | astronomy | the scientific study of the universe; It includes the observation and interpretation of celestial bodies and phenomena | 0 | |
| 206487679 | retrograde motion | the apparent westward motion of the planets with respect to the stars | 1 | |
| 206487680 | astronomical unit (AU) | average distance from the Earth to the sun; 1.5 × 10⁸, or million kilometers | 2 | |
| 206487681 | ellipse | has a semi-major and major axis and two foci. | 3 | |
| 206487682 | rotation | the spinning of a body, such as earth, about its axis | 4 | |
| 206487683 | revolution | the motion of one body about another, as Earth about the sun | 5 | |
| 206487684 | precession | a slow motion of Earth's axis that traces out a cone over a period of 26,000 years | 6 | |
| 206487685 | perihelion | the point in the orbit of a planet where it is closest to the sun | 7 | |
| 206487686 | aphelion | the place in the orbit of a planet where the planet is farthest from the sun | 8 | |
| 206487687 | perigee | the point at which the moon is closest to the Earth | 9 | |
| 206487688 | apogee | the point where the moon is farthest from Earth | 10 | |
| 206487689 | phases of the moon | the progression of changes in the moon's appearance during the month. In order- New moon, waxing crescent, 1st quarter, waxing gibbous, full moon, waning gibbous, 3rd quarter, waxing crescent. | 11 | |
| 206487690 | nebula | A cloud of dust, gas or both in space. Where star clusters are formed. | 12 | |
| 206487691 | planetesimals | A small, irregular shaped body formed by colliding matter. | 13 | |
| 206487692 | Geocentric Model | the model where the planets, sun, and moon orbit Earth | 14 | |
| 206487693 | Heliocentric Model | the model where Earth and other planets orbit the sun | 15 | |
| 206487694 | Claudius Ptolemy | About 140 AD in the Alexandria • Fit universe to a mathematical model • Geocentric • Uniform circular motion • Epicycles and deferents • Very accurately predicted planet positions (at first) | 16 | |
| 206487695 | Nicolaus Copernicus | • Proposed a heliocentric universe • Motivated to reinstate uniform circular motion in its purest form • Retrograde motion was a natural result of the Earth's motion • Needed more epicycles than Ptolemy • Predictions were no better than the Alfonsine Tables • Revolutionized humankind's view of the Earth | 17 | |
| 206487696 | Tycho Brahe | • Decades of accurate observations • No parallax for the nova of 1572 • Placed the nova past the Moon • De Stella Nova, made him famous in educated circles • No parallax for stars • Favored the Herakleides cosmology | 18 | |
| 206487697 | Kepler law #1 | all planets orbit sun in ellipse | 19 | |
| 206487698 | Kepler law #2 | when a planet is closer to the sun in its orbit, it moves faster | 20 | |
| 206487699 | Kepler law #3 | p²=a³ when p is an orbital period in yrs, and a is the avg dist. from the sun in AU | 21 | |
| 206487700 | Galileo Galilei | -discovered how bodies fell -first to use telescope for scientific purposes -discovered moons are imperfect -discovered Jupiter's moons -claimed discovery of sun-spots (actually Jesuits) -work resulted in Decree of 1616, no one allowed to teach Copernican model | 22 | |
| 206487701 | Sir Isaac Newton | -created three laws of motion -invented integral calc | 23 | |
| 206487702 | 29 ½ days | time from new moon --> new moon | 24 | |
| 206487703 | 27 1/3 days | days it takes moons orbit around earth | 25 | |
| 206487704 | synodic month | new moon --> new moon is called | 26 | |
| 206487705 | sidereal month | earth, moon, and star are all aligned | 27 | |
| 206487706 | umbra | region where sunlight is completely blocked | 28 | |
| 206487707 | penumbra | region where sunlight is partially blocked | 29 | |
| 206487708 | meteorite | a meteoroid that actually reaches earth's surface | 30 | |
| 206487710 | Lunar Eclipse | the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon | 31 | |
| 206487711 | Solar Eclipse | occurs when the Moon passes directly between the Sun and Earth and casts a shadow over part of Earth | 32 | |
| 206487712 | universe | the total sum of all matter and energy | 33 | |
| 206487713 | star | large, glowing ball of gas that generates heat and light via nuclear fusion | 34 | |
| 206487714 | planet | In order for an object to be considered a planet it must orbit a star (but neither be a star nor a moon), be massive enough to give it a nearly round shape, and clear the neighborhood around its orbit. If an object meets the first two criteria, but not the third, it is a dwarf planet. | 35 | |
| 206487715 | moon | object that orbits planet | 36 | |
| 206487716 | asteroid | a relatively small and rocky object that orbits a star | 37 | |
| 206487717 | comet | a small, icy object that orbits a star | 38 | |
| 206487718 | small solar system body | an asteroid, comet, or other object that orbits a star, but doesn't qualify as a planet or dwarf planet | 39 | |
| 206487719 | solar system | a star (or sometimes more than one star) and all the objects that orbit it in its gravitational field. | 40 | |
| 206487720 | star system | a star, and any planets or other materials that orbit it | 41 | |
| 206487721 | galaxy | A galaxy is a huge collection of stars bound together by gravity at a common center | 42 | |
| 206487722 | galaxy cluster | a collection of galaxies bound together by gravity (called a group if small collection, and a cluster if large collection) | 43 | |
| 206487723 | supercluster | a gigantic region of space where many individual galaxies are packed closely | 44 | |
| 206487724 | observable universe | the portion of the entire universe that can be seen from earth on principle- 14 billion light years in all directions | 45 | |
| 206487726 | Planets in order away from the sun | Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and (not really per se) Pluto | 46 | |
| 206487727 | Edwin Hubble | 1.) Every galaxy is moving away from us. 2.) The further the galaxy, the faster it is moving | 47 | |
| 206487728 | constellations | a region of the sky with defined borders | 48 | |
| 206487729 | zenith | the point above the observer that is directly opposite the nadir on the imaginary sphere against which celestial bodies appear to be projected | 49 | |
| 206487730 | meridian | imaginary line drawn from the horizon due north to due south | 50 | |
| 206487731 | azimuth | direction of a celestial object, degrees clockwise from due North, and it's altitude above the horizon | 51 | |
| 206487732 | Summer Solstice | June 21 | 52 | |
| 206487733 | Winter Solstice | December 22, when the sun is at its southernmost point | 53 | |
| 206487734 | Spring Equinox | March 21 | 54 | |
| 206487735 | Fall Equinox | September 22 | 55 | |
| 206487736 | lunar eclipse | earth lies between sun and moon | 56 | |
| 206487737 | solar eclipse | moon lies between sun and the earth | 57 | |
| 206487738 | nodes of orbit | where moon crosses elliptic plane | 58 | |
| 206487739 | conditions for ellipse | 1.) Moon must be fill 2.) Nodes must be aligned | 59 | |
| 206487740 | Types of lunar eclipes | 1.) total- moon passes through umbra 2.) partial- part of moon passes through umbra 3.) penumbral- moon passes through prenumbra | 60 | |
| 206487741 | Types of solar eclipses | 1.) total- occurs in area that falls in the moon's umbral shadow 2.) partial- occurs in the area falling the the penumbral shadow 3.) annular- occurs when the umbral shadow doesn't reach the earth, where the umbral shadow would've hit | 61 | |
| 206487742 | stellar paralax | when stars shift back and forth against back-ground of distant stars | 62 | |
| 206487743 | metonic cycle | 19 year cycle on which the dates of the lunar cycle repeat, Named for Greek astronomer Meton | 63 | |
| 206487744 | light year | distance it takes light to travel in one year (10 trillion KM) | 64 | |
| 206487745 | tilt of earth's axis perpendicular to elliptic plane | 23.5 degrees | 65 | |
| 206487746 | order of magnitude estimate | estimates to nearest power of 10 | 66 | |
| 206487747 | saros cycle | occurs every 18 years and 11 1/3 days. combination of changing eclipse seasons and lunar cycles. | 67 | |
| 206487748 | Pythagoras | • Earth a sphere • Sun, Moon and planets on wheels • The music of the spheres • Only the master could hear the music | 68 | |
| 206487749 | Philolaus | -first to suggest earth moved -believed earth moved around central fire | 69 | |
| 206487750 | Aristarchus | heliocentric model | 70 | |
| 206487751 | Herakleides | planets orbit sun, sun orbits earth (couldn't see stellar parallax) | 71 | |
| 206487752 | Plato | -Taught observation is useless -heavens were perfect, planets spheres, motion was uniform | 72 | |
| 206487753 | Aristotle | -taught earth didn't move -heaven and earth different spheres | 73 | |
| 206487754 | Ptolemy | -geocentric solar system -made accurate predictions of planets for some time | 74 | |
| 206487755 | 5 Obstacles to Astronomy Copernican Revolution | -Separate earth and heavens -geocentric dogma -dogma of circular motion -science w/o math -misunderstanding of motion | 75 | |
| 206487756 | Copernican Revolution | Heliocentric model | 76 | |
| 206487757 | Newton's Three Laws | 1. A object in motion tend to stay in motion unless acted on by another force. 2.f=ma 3. Every action has a equal and opposite reaction | 77 | |
| 206487758 | Halley | • Actually paid for the publication of the Principia, Newton's book on physics which contained the law of gravity. • Showed that the orbit the comet of 1682 was the same as the orbit of the comets of 1531 & 1607 | 78 | |
| 206495122 | small angle formula | angular size= physical size(360/2πdistance) | 79 |
