Lesson 2: Patterns in the Sky
Lesson 2: Patterns in the Sky ASTR 101
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This 3 page Class Notes was uploaded by Evan Kirkpatrick on Sunday October 4, 2015. The Class Notes belongs to ASTR 101 at University of Washington taught by Ana Larson in Fall 2015. Since its upload, it has received 21 views. For similar materials see ASTRONOMY (NW,QSR) in Environmental Science at University of Washington.
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Date Created: 10/04/15
Lesson 2 Patterns in the Sky Vocab The C Celestial Sphere An imaginary sphere created around the Earth to help visualize surrounding planets and stars Apparent Daily Motion the path each objet makes across the sky each day North Celestial Pole NCP A point directly above Earth s North Pole South Celestial Pole SCP A point directly above Earth s South Pole Ecliptic The suns path in the sky Celestial Equator Above Earth s equator and divides the sphere into North and South Zenith The point in the sky directly above wherever you are Meridian Imaginary line running from North to South that divides the sphere into Western and Eastern hemispheres Altitude Angle above the horizon Latitude Measures where you are in terms of north or south of the equator Measured by angle from the equator with the NorthSouth pole being 90 degrees Circumpolar Stars Stars that never dip below the horizon of the NCP Ecliptic Plane The plane created by Earths orbit around the Sun Zodiac Constellations Constellations along the ecliptic Summer Solstice A day when the sun is highest above the meridian Winter Solstice Shortest day of the year Autumnal and Vernal Equinoxes Exactly 12 hours of sunlight in one day Gregorian Calendar Calendar based on tropical year Tropical Year The time between two vernal equinoxes Synchronous Rotation The same side of the moon always faces Earth Full Moon The Earth is between the Sun and the moon New Moon The Moon is between the Earth and the Sun elestial Sphere We don t feel the motion or direction of Earth spinning North Pole is located on the North end of Earth s rotational axis Earth carries us from west to east so objects in the sky appear to go from east to west Each point on the sphere represents a point in space The angle between the NCPSCP and the celestial equator is always 90 degrees Daily motion varies based on where you are View from the Poles Objects closer to the poles have smaller circles while the Earth rotates Objects closer to the equator have larger circles while the Earth rotates North pole appears to move counterclockwise around the sky South pole appears to move clockwise around the sky You can view all stars during a 24hour day at the equator Earth and the Sun Earth is 15 x 10quot8 km away from the Sun Astronomical Unit or AU Seasons are not caused by Earth being closer or further from the sun Seasons are caused by the tilt of the Earth 0 When the North pole faces the Sun the Northern Hemisphere is in summer 0 When the South pole faces the Sun the Southern Hemisphere is in summer During the summer the Sun s rays beat directly onto the Earth s surface which heats the Earth s surface more than it would during the winter 0 Also more hours of sunlight during summer cause warmer weather Solar eclipses don t happen twice every month because the moons orbit isn t in the same plane as the ecliptic plane Every year has an extra quarter of a day so every 4 years there is a leap year to account for the extra day Earth s axis wobbles very slowly 0 26000 years for a full cycle 0 This also causes Earth s celestial equator to wobble because it is always perpendicular to the axis 0 This change in equinox position is called precession of the equinoxes Seasons and Locations Day length varies a lot near the poles Artic and Antarctic Circles have parts of the year when they receive 24 hours of sunlight and other days when they receive 0 hours of sunlight o The sunlight is never very direct so the two poles stay cold On the equator days and nights are 12 hours long year round Two bands 235 degrees south and north of the equator are called the tropics 0 North is Tropic of Cancer 0 South is Tropic of Capricorn 0 These two locations are perpendicular to the sun twice every year The Moon s Orbit The moon orbits the Earth in a complete cycle in 27 days The moon rotates on its axis and completes it s turn in the same amount of days it takes to orbit Earth 0 Therefore we always see the same side of the moon The moon is always half illuminated and half dark from the sunlight The Moon s light cycle 0 New Moon Waxing Crescent First Quarter Waxing Gibbous Full Moon Waning Gibbous Third Quarter Waning Crescentrepeat Solar eclipse occurs when the Moon passes between the Sun and the Ea h 0 Total Solar Eclipse Lasts only 7 minutes occurs when the Sun and Moon and Earth all line up in a straight line 0 Partial Solar Eclipse Occurs when the Moon partially covers the Sun 0 Annular Solar Eclipse Occurs when the Sun can be seen as a ring around the portion blocked by the moon Lunar eclipse occurs when the Earth is between the Sun and the Moon 0 Total Lunar Eclipse BloodRed Moon Lasts about an hour and happens when all three are in a direct line with each other 0 Partial Lunar Eclipse When Earth s shadow covers only part of the Moon
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