AUTUMN Equinox September 22-23 WINTER Solstice December 21-22 SUMMER Solstice June 21-22 SPRING Equinox March 19-20 While the Northern Hemisphere is tilted toward the sun the sun’s rays called solar radiation hit the Northern Hemisphere more directly That more direct angle means more heat giving us summer At the same time solar radiation reaches the Southern Hemisphere less directly The rays travel farther and lose more heat creating winter in the south Six months later when the positions are reversed the Southern Hemisphere enjoys summer while it’s winter in the north 6
Twice a year the sun shines Spring and Autumnal Equinox Days directly on the equator as it passes from the Northern Hemisphere to the Southern Hemisphere and then back again Each of these days is called an equinox The spring equinox or vernal equinox for the Northern Hemisphere occurs around March 19-20 when the sun passes from the south to the north The autumnal equinox occurs around September 23 when the sun crosses from the north to south The Northern Hemisphere’s spring equinox is the Southern Hemisphere’s autumnal equinox The farther from the equator you get the lower the winter sun will sit in the sky because it travels a shorter distance across the sky You might have noticed the days get longer in the summertime and shorter in the wintertime That’s because the sun follows a longer path higher in the sky when it’s more directly opposite the Earth in the summer The longest day of the year is the summer solstice occurring between June 20 and 22 in the Northern Hemisphere The winter solstice is the shortest day of the year when the sun follows the shortest path across the sky Winter solstice occurs around December 21 to 22 The equator running along the middle of the Earth gets similar amounts of sunlight all year long because the angle of the sun’s rays is similar Seasons at the equator are also mild equator 7
The Moon and the Tides Just as the Earth revolves around the sun the moon revolves around the Earth The moon takes about 27 days to complete one revolution around the Earth During this time the moon goes through lunar phases It appears to get bigger called waxing and then smaller called waning But the moon really isn’t changing at all It just looks that way From Earth we can only see the part of the moon lit up by the sun How much sunlight reflects off the moon depends on where it is in its trip around Earth 8
The Lunar Phases There are eight lunar phases The first is a new moon which actually looks like no moon A new moon is directly between the Earth and sun and we cannot see the side lit by the sun As it continues to revolve around Earth we start to see a small sliver of it a crescent moon Next is a quarter moon when we see a half circle Halfway between a quarter moon and full moon is a gibbous moon Finally we see a completely lit circle a full moon halfway through the moon’s journey It passes through another gibbous quarter and crescent moon on its way back to a new moon Full Moon Craziness People used to believe that the full moon made people go crazy The word lunacy which means insanity comes from the word lunar Even today many people believe the full moon brings more traffic accidents more crime busier emergency rooms and other strange occurrences In reality scientists have not found that these things happen any more often during a full moon than at other times during the year waning crescent waning quarter waning gibbous new full waxing crescent waning gibbous waxing quarter 9
