Instructions for Side by Side Printing
- Print the notecards
- Fold each page in half along the solid vertical line
- Cut out the notecards by cutting along each horizontal dotted line
- Optional: Glue, tape or staple the ends of each notecard together
Wanderers in Space, Key Terminology
front 1 what does modern science offer answers to? | back 1 fundamental questions about the universe and our place within it |
front 2 what do we know about the universe according to modern science? | back 2 basic content and scale of the universe ages of Earth and the universe |
front 3 scale of the universe | back 3 size and extent of the universe - includes basic content and structure |
front 4 history of the universe | back 4 development and changes in universe from its beginning to the present |
front 5 star | back 5 a large, glowing ball of charged gas that generates heat and light through nuclear fusion in its core "nuclear furnace" |
front 6 solar / stellar system | back 6 a star and all the materials that orbit it -- including planets and moons |
front 7 Milky Way galaxy | back 7 - our galaxy - the band of light we see in the sky when we look into the plane of our galaxy |
front 8 galaxy | back 8 - great "island" of stars in space - all held together by gravity - orbit a common center |
front 9 local group | back 9 group of about 40 galaxies to which Milky Way galaxy belongs - one of the two largest among them is Milky Way |
front 10 galaxy clusters | back 10 collection of a few dozen or more galaxies bound together by gravity - smaller collections called groups |
front 11 superclusters | back 11 clusters of galaxy clusters largest known structures in the universe |
front 12 Laniakea | back 12 local supercluster translates to "immense heaven" |
front 13 light year & kilometers conversion | back 13 1 light-year = 9.46 trillion km |
front 14 astronomical unit | back 14 average distance (semimajor axis) from Earth to the Sun ~93 million miles (150 million kilometers) |
front 15 light year | back 15 distance that light can travel in one year approx. 10 trillion kilometers |
front 16 the farther away we look in the distance... | back 16 the further back we look in time |
front 17 structure of galaxies and galaxy clusters | back 17 arranged in giant chains and sheets with huge voids between them |
front 18 planet | back 18 - moderately large object that orbits a star - shines primarily by reflected light (from its star) may be rocky, icy, or gaseous in composition |
front 19 moon | back 19 object that orbits a planet |
front 20 satellite | back 20 any object orbiting another object |
front 21 asteroid | back 21 relatively small & rocky object that orbits a star |
front 22 comet | back 22 relatively small & ice rich object that orbits a star |
front 23 small solar system body | back 23 asteroid, comet, or other object that orbits a star too small to qualify as a planet or dwarf planet |
front 24 universe | back 24 sum total of all matter and energy - all galaxies and everything in between them |
front 25 observable universe | back 25 portion of the entire universe that can be seen from Earth |
front 26 exoplanet | back 26 planets in other solar systems around other stars |
front 27 nebula | back 27 interstellar cloud of gas and dust how stars and stellar systems are formed |
front 28 TNOs | back 28 dwarf planets trans-neptunian objects |
front 29 rotation | back 29 spinning of an object around its axis |
front 30 orbit (revolution) | back 30 orbital motion of one object around another due to gravity |
front 31 measured age of the universe | back 31 14 billion years boundary of our observable universe |
front 32 expansion (of the universe) | back 32 increase in average distance between galaxies as time progresses |
front 33 levels of the universe | back 33 earth -> inner solar system -> outer solar system -> closest stars -> Milky Way -> local group -> laniakea -> local superclusters -> observable universe |
front 34 solar day | back 34 time for the sun to return to the meridian avg. 24 hours |
front 35 sidereal day | back 35 time for a distant star to return to the meridian after a rotation 23 hours, 56 minutes, 4 seconds *Earth's TRUE rotation rate* |
front 36 why are the solar day and sidereal day different? | back 36 Earth also has to revolve around the Sun in our orbit and have to turn a tiny bit more to face the sun again |
front 37 north celestial pole | back 37 directly above Earth's North Pole |
front 38 ecliptic | back 38 the Sun's apparent annual path around the celestial sphere |
front 39 geocentric universe | back 39 ancient belief that universe is "Earth-centered" ie. Earth is center of universe and all other celestial bodies orbit around Earth |
front 40 ecliptic plane | back 40 Earth's orbital path |
front 41 celestial sphere | back 41 puts stars and constellations onto an imaginary sphere around us *not realistic, just how it appears to us from Earth |
front 42 earth moves from | back 42 west -> east |
front 43 what direction do the sun, moon, planets, and stars all appear to rise and set? | back 43 east -> west |
front 44 what direction does earth spin? | back 44 counterclockwise (when viewed from above the North Pole) |
front 45 how much is earth's axis tilted? | back 45 23.5 degrees (from a line perpendicular to the ecliptic plane) |
front 46 earths axis remains pointed... | back 46 in the same direction in space throughout the year |
front 47 earths orbit moves... | back 47 in the same counterclockwise direction as its rotation |
front 48 earth's axis points toward the star... | back 48 Polaris - the North Star, always found in a direction of due north |
front 49 earths distance from the sun... | back 49 varies slightly over the course of the each year |
front 50 earth orbits the sun in the same direction that... | back 50 it rotates on its axis |
front 51 local solar neighborhood | back 51 region of the Sun and nearby stars |
front 52 dark matter | back 52 matter inferred to exist from gravitational effects, but no light has been detected - dominates total mass of the universe |
front 53 dark energy | back 53 energy that could be causing the expansion of the universe to accelerate |
front 54 virtually every galaxy outside the local group is moving... | back 54 away from us |
front 55 the more distant the galaxy... | back 55 the faster it appears to be racing away |
front 56 raisin cake | back 56 analogy to explain expansion of universe expansion of cake causes raisins to move away from local raisin -- more distant raisins move away faster |
front 57 distant galaxies are all moving away from us, with more distant ones moving faster... | back 57 indicating that we live in an expanding universe |
front 58 how do observations of expansion allow us to measure the age of the universe? | back 58 faster the rate of expansion, the more quickly galaxies reach their current position -- therefore the younger the universe must be |
front 59 problems with raisin cake analogy | back 59 - cake has center and edges; same may not be true for the universe ( no place is more central than any other place) -can't see galaxies moving apart with time |
front 60 Doppler shifts | back 60 way of measuring speeds of galaxies via spreading their light into these spectra |
front 61 constellations | back 61 region of the night sky with well-defined borders familiar star patterns help us find them |
front 62 south celestial pole | back 62 point directly over Earth's South Pole |
front 63 celestial equator | back 63 projection of Earth's equator into space - makes a complete circle around the celestial sphere |
front 64 Milky Way | back 64 band of light that circles around celestial sphere - traces our galaxy's disk of stars-- the galactic plane-- as it appears from our location within the galaxy |
front 65 local sky | back 65 sky as seen from wherever you happen to be standing |
front 66 horizon | back 66 boundary between earth and sky |
front 67 zenith | back 67 point directly overhead (in sky) |
front 68 meridian | back 68 imaginary half-circle stretching from horizon due south, through the zenith, to the horizon due north |
front 69 direction | back 69 one of two coordinates needed to pinpoint an object in the local sky |
front 70 altitude | back 70 (above horizon) the angular distance between the horizon and an object in the sky |
front 71 declination | back 71 north-south location on sky (like latitude) (degrees, arcminutes, arcseconds) |
front 72 right ascension | back 72 east-west location on sky (like longitude) hours, minutes, seconds |
front 73 angular size | back 73 (of an object) the angle it appears to span in your field of view - also depends on distance |
front 74 angular distance | back 74 (between objects) angle that appears to separate them |
front 75 celestial sphere appears to rotate... | back 75 east to west |
front 76 circumpolar | back 76 star that always remains above the horizon for a particular latitude |
front 77 stars near south celestial pole... | back 77 never rise above horizon at all |
front 78 0 point for right ascension | back 78 where the sun crosses the celestial equator on the march equinox |
front 79 the farther away an object is... | back 79 the smaller its angular size |
front 80 stars near North Pole are... | back 80 circumpolar, meaning that they remain perpetually above the horizon, circling (counterclockwise) around the north celestial pole each day |
front 81 stars near south celestial pole... | back 81 never rise above the horizon at all |
front 82 others stars have daily circles that are... | back 82 partly above the horizon & partly below why they appear to rise in the east and set in the west |
front 83 positive declination | back 83 north of the equator |
front 84 negative declination | back 84 south of the equator |
front 85 relationship between angular size (in degrees), physical size, and distance | back 85 angular size/360 degrees = physical size / 2pi x distance |
front 86 does the sky vary with latitude or longitude? | back 86 latitude |
front 87 the altitude of the celestial pole in your sky = | back 87 your latitude |
front 88 the constellations visible at a particular time of night... | back 88 change as we orbit the Sun |
front 89 Earth's axis points in the same direction all year round, which means... | back 89 its orientation relative to the Sun changes as Earth orbits the Sun |
front 90 If Earth did not have an axis tilt... | back 90 we would NOT have seasons |
front 91 summer solstice (June solstice) | back 91 occurs around June 21st moment when the Northern Hemisphere is tipped most directly toward the Sun - receives the most direct sunlight |
front 92 winter solstice (December solstice) | back 92 occurs around December 21st the moment when the Northern Hemisphere receives the least direct sunlight |
front 93 spring/ vernal equinox (March equinox) | back 93 Northern Hemisphere goes from being tipped slightly away from the Sun to being tipped slightly toward the sun |
front 94 fall/ autumnal equinox (September equinox) | back 94 moment when the Northern Hemisphere first starts to be tipped away from the sun |
front 95 we use equinoxes and solstices to mark... | back 95 the progression of the seasons |
front 96 equinox | back 96 sun rises precisely due east and sets precisely due west |
front 97 solstice | back 97 Sun rises and sets farthest to the north of due east and due west |
front 98 high latitudes have... | back 98 more extreme seasons |
front 99 precession | back 99 gradual wobble that alters the orientation of Earth's axis in space |
front 100 the tilt of Earth's axis remains close to 23.5 degrees, but... | back 100 the direction the axis points in space changes slowly with the 26,000-year cycle of precession |
front 101 what causes precession? | back 101 gravity's effect on a tilted, rotating object |
front 102 lunar phases | back 102 Moon's appearance in the sky changes as its position relative to the sun changes |
front 103 the sun comes from essentially the same direction... | back 103 all along the Moon's orbit |
front 104 moon phase takeaways | back 104 - we always see the same side of the moon facing Earth - as moon orbits Earth, we see different combinations of its bright and dark faces |
front 105 the phase of the moon depends on... | back 105 its position relative to the Sun as it orbits Earth |
front 106 the moon's phase affects not only its appearance but also... | back 106 its rise and set times |
front 107 new moon | back 107  rises and sets with sun |
front 108 waning crescent | back 108  rise: before dawn highest: mid-morning set: mid-afternoon |
front 109 third quarter | back 109 rise: midnight |