8th grade-ch. 1 sec. 1 earth in space
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Ch. 1 Sec. 1 Earth in Space
astronomy
• study of moon, stars & other objects in space
rotation
Earth spinson its axis 24 hours causes
day & night
imaginary linethat passes
thru Earth’s ctr. & N. & S. Poles
revolution• movement of 1 object around
another
orbit• Earth’s
path as it revolves around Sun
• not round-ellipse (oval)
Earth rotates as it revolves.
Sun
Earth
calendar
• system of organizing time that defines beginning, length & divisions of a year
leap year• 1 year = 365 ¼ days• ¼ + ¼ + ¼ + ¼ = 1 day
leap year every 4 years
1. tilt of Earth’s axis
2. Earth’s revolution
around sun
When the Northern Hemisphere is having summer, Earth is actually at its greatest
distance from the sun.
Near the equator, sunlight strikes Earth’s surface more directly and is less spread out than near the poles.
Earth has seasons because it is tilted as it revolvesaround the sun.
vernalequinox
March 21- noon sun directly over equator
autumnalequinox
Sept. 23- noon sun directly over equator
winter solstice
Dec. 21- shortest day of year-noon sun 23.5 O N
summersolstice
June 21- longest day of year-noon sun 23.5 O S
Seasons in the Northern Hemisphere
equinox
solstice
Equinox means "Equal Night"
1. What causes the Earth's seasons? 2. During which season do the Sun's rays hit the Earth at the most direct angle? 3. During which season are the days the shortest? 4. What is the name and date of the shortest day of the year (and the beginning of winter)? 5. What is the name and date of the longest day of the year (and the beginning of summer)? 6. What is the name of a day in which the day and night are of equal duration? 7. How many times each year do we have days in which the day and night are of equal duration?
Earth’s seasons quiz