2.1, 4.1, 4.2 Notes

Terms to refresh your memory

• AM: anti-meridian
• PM: Post-meridian
• solar noon: the highest point the sun is in the sky
• longitude: angle measured from prime meridian
• -east to west
• latitude: angle from equator
• -north to south
• circumpolar: objects near the north pole that never seem to set

Slide 2

• Constellation- one of 88 sectors of the sky
• asterism - star pattern within a constellation
• ecliptic - path sun takes around celestial sphere
• declination - angular distance of a point North or South of the celestial equator
• right ascension - the distance of a point measured by the East of the First Point of Aries, measured along the celestial equator and expressed in hours, minutes, and seconds.
• celestial equator - the projection into space of the earth's equator, equidistant from the celestial poles
• equator - great circle constituting of the parallel 0 degrees, dividing the earth into hemispheres
• First Point of Aries: vernal equinox

Things to Note

• *the sky rotates opposite of the celestial poles
• *rises on east, sets in west
• -The star Polaris is also known as the fastener of the sky
• *earth rotates counterclockwise
• *planet means "wanderer" in Greek
• *halfway b/w the poles, 90 degrees, is the celestial equator

Declination and Right Ascension

• Declination is measured just the same as latitude (from the equator)
• North: positive values South: negative values
• Right Ascension is similar to longitude, but counted from the "vernal equinox" , where the ecliptic crosses the celestial equator.
• 360 degrees = 24 hours
• 15 degrees = 1 hour

Seasons

• *become more pronounced the further N or S one travels from the equator
• Seasons are not caused by the distance earth is from the sun, but rather by the degree of the earth's axis tilt (23.5 degrees.)
• The vernal and autumnal equinoxes deliver equal amounts of sunlight across the globe
• The North leans in toward the sun during the summer solstice, and away during the winter solstice
• The South leans in toward the sun during the winter solstice, and away during the summer solstice
• The angle determines the intensity/where the earth receives the most sunlight (heating distribution)
• During the summer, The north receives the most hours of sunlight
• During the equinoxes, the both hemispheres receive equal hourly amounts of sunlight
• During the winter, the South receives the most hours of sunlight

Slide 6