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"Seeing" the Earth, Moon, and Sun to ScaleThe moon is about 1.3 light-seconds away (240,000 miles). Here is a scale picture of the Earth-moon system, with the earth (actual diameter: 8,000 miles) represented by a circle just a little bigger than 1/8 inch: (Remember this picture the next time you watch the movie Apollo 13!) The sun is 8.3 light-minutes away (93,000,000 miles). A scale drawing is not as easily made here as it was for the Earth and moon above. If we chose the same 1/8 inch diameter circle to represent the earth, then we would require a circle bigger than one foot in diameter to represent the sun (actual diameter: 864,000 miles). The center of the sun circle would have to be placed about 121 feet from the center of the earth circle! You can begin to be impressed by the different sizes and separations that we encounter in space. The terms light-seconds and light-minutes are used as units of distance along with light-years. These units may be understood as distances, or in another way. When we look up, we see the moon and sun, not as they are now, but as they were 1.3 seconds and 8.3 minutes ago, respectively. Hence, the concept of the space-time continuum: the further out we look into space, the farther back we see into time. |
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Please send suggestions/corrections to: Web Related: David.Mazza@grc.nasa.gov Technology Related: Joseph.C.Kolecki@grc.nasa.gov Responsible NASA Official: Theresa.M.Scott (Acting) |