Show weeley guide to tn 8 y science by permission of POPULAR rocci AR SCIENCE montile N M HAT CAUSES THE TIDES the attraction ot of gravity ot of the moon with some help irom from the other heavenly bodies As the earth turns around the moon attracts the water in the ocean and raises a bulge in it this bulge Is the tide DOES THE SUN AFFECT THE TIDES yes tes it attracts the water just ns as the moon does but less strongly because it Is so much farther away even the other planets have an attraction on the water and an effect although a small email one on the tides HOW ARE THE TIMES TIDES astronomers can calculate the exact place of the moon sun etc in the heavens tor for any specified tune time they can also e calculate alc just how strongly each of them pulls on the ocean water by watching and measuring the tides lor for amany years men have learned how things like the shore lines the ocean currents etc affect them putting the effects of these things together the tides can be calculated WHY DO WE HAVE M AN N EXTRA DAY IN LEW TEAR one year Is the time it takes the earth to go entirely around the sun and come back to the same place in ia orbit it happens that a year does docs not equal an exact number of days it Is about days so an extra day must be added ev every ry fourth year in order to keep the ca lendar calendar exactly even with the time the earth takes to travel its complete orbit WHAT DO LATITUDE AND AND LONGITUDE aicon the latitude of a place Is its distance from the center line around the earth the equator its longitude Is its distance irom from any selected circle drawn around the earth through the poles for instance the longitude west of greenwich Is the distance west of the circle which passes through the poles polea and also through the town of greenwich in england there where the royal koyal astronomical observatory Is located HOW CAN YOU LOCATE till POSITION OF 01 A PLACE ON EARTH by giving its latitude and longitude both are given in degrees that Is in ol of the entire circumference ot of the earth thus 45 degrees north latitude Is just halt half the distance from the equator to the north pole ninety degrees longitude west of greenwich means just one fourth ol of the way around the earth measured from the circle drawn through greenwich and the pole WHY IS THERE LIGHT 11 IN THE DAYTIME A EVEN WHEN HE THE SUN IS HIDDEN BY CLOUDS the sun run Is shinning on the top of the clouds part of this light gets through just as some light wll will shine through a white cloth is THE SKY BLUE ku all through the air even when it Is purest there are many millions 61 tiny particles of matter some are specks of 0 dust sonie some are water particles some are the molecules of air itself all of them are far too small tor for us to see but they reflect a little light because of one of 0 the physical laws of light this reflected light Is of a bluish color HOW CAN TRUE NORTH BE determined BY THE STARS the place in the heavens where the stars stare do not term seem to move at all us as the earth revolves marks the direction of the pole there happens not to be any star visible to the naked eye exactly at this point but the star called the polestar pole star is very close to the proper place and this star Is commonly used by surveyors to find the north COULD THE SKY FALL DOWN no the sky la Is not anything solid it Is merely the way the air looks i to us when we took look up through it wo we tire are really looking out into space through a blanket of air much as fish look up into the air through a blanket of water WHY 19 IS TUB THE SKY orten OFTEN RED AT SUNSET when there Is much dust in the air light shining through it la Is colored reddish the sun seen through smoke emoke which Is really very fine dust looks red at sunset and sunrise the s sunlight has ITI lIght to pass through a thicker layer Y ot f air ir than at noon and if the air Is dusty at all the sun Is apt to look red kiy DO WE SOMETIMES SEE A RING AROUND THE MOON because the moonlight Is being reflected from millions of tiny particles usually small ice crystals which are floating in the air these little crystals act like a multitude ot of tiny mirrors and the light from all ot of them combines to form a ring IS A RAINBOW remember that a glass prism will split light up into the seven primary colors A group ot of drops ot of water will do the same thing it if the sun shines onto such a cloud ot of water drops as in a shower of rain the light reflected back to you from the drops has been split and hence you see a rainbow WHY IS THE RAINBOW CURVED carved As the sunlight Is split into colors most of them are sent in such directions that you cannot see them only a narrow band of them coming along the surface ot of a particular cone will reach your you eye the base of a cone Is a ring but the lower part of this ring Is cut off by the erth erath so that only the upper part shows each person sees a different rainbow WHEN THE SUN IS SHINNING THRU HOLES IN A CLOVI IT IS SAID TO BC DRAWING LP WATER IS THIS TRIE no the appearance of rays or be beams of 1 sunlight Is caused by fine dust ct in the 1 I air just as a ray of sunlight entering a dark room will light up dust motes in the air so that you can see the path of the beam |