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Home , Earth, Moon, Sun

Unit 5: -- Key Concepts

Earth – Sun

 The earth revolves around the sun over 365.25 days  Earth rotates on its axis every 24 ; giving in areas facing the sun and in areas facing away from the sun  The Pole of the Earth’s axis always points to the North ()  : The seasons occur because there are different amounts of direct and hours of daylight as the Earth revolves around the sun. If the Earth’s axis was not tilted, then the seasons would not occur o - the is angled towards the sun, and the experiences warmer and longer days. . June 20-21 is the summer , the longest of the in the northern hemisphere. On this day, the sun is directly overhead at the Tropic of and areas above the Circle have 24 hours per day of daylight . The northern hemisphere’s summer occurs as the has its o Winter – the North Pole is angled away from the sun, and the northern hemisphere experiences colder weather and shorter days . -22 is the , the shortest day of the year in the northern hemisphere. On this day, the sun is directly overhead at the and areas above the receive 24 hours per day of . The northern hemisphere’s winter occurs as the southern hemisphere has its summer o and Autumn – during the equinox, the days and are of approximately equal length, and the sun is directly over the

Unit 5: Earth-Sun-Moon Key Concepts

Earth – Moon System

 The Moon revolves around the earth leading to the phases of the Moon cycle which occur over ≈ 28 days, as the Moon completes one revolution around the Earth  The same phase of the Moon cycle will be viewed by all places on earth as the earth rotates through a 24 day.  Moon Phases o – when the Earth is facing the dark half of the moon. The Moon is in- between the Earth and Sun o Waxing – as the Moon revolves around the Earth, the lighted portion comes into view o First Quarter – the Moon, Earth, and Sun make a 90° and half of the lighted portion of the Moon can be seen o Waxing Gibbous – most of the Moon’s lighted portion can be seen from Earth o – All of the Moon’s lighted portion can be seen from Earth. The Earth is in-between the Moon and Sun. o Waning Gibbous – the lighted portion of the Moon starts to decrease from Full. o Third Quarter – the Moon, Earth, and the Sun make a 90° angle and half of the lighted portion of the Moon can be seen o Waning Crescent – as the Moon come close to completing its revolution around the Earth, a small portion of the lighted side of the Moon is visible  o – when the Moon travels in-between the Earth and Sun and the Moon’s falls on the Earth. Only occurs during a New Moon o – when the Earth travels in-between the Moon and Sun and the Earth’s shadow falls on the Moon. Only occurs during a Full Moon  o Rising and falling of the due to the Moon’s gravitational pull o The sun also has an influence on tides o Two high tides and two low tides occur each day. o There is approximately 6 hours between high and low o Spring tides occur during the New Moon and Full Moon when the Moon and Sun’s gravitational act together to produce higher high-tides than usual and lower low-tides than usual. The is much larger than usual o Neap tides occur during the first and third quarter phases of the Moon cycle when the Moon and Sun’s gravitational forces work against one another. The tidal range is much smaller than usual.