The Basics of Astronomy

Size and Scale of the Universe

To Quote the Hitchhikers Guide to the Galaxy, “’Space,’ [The Guide] says, ‘is big. Really big. You just won’t believe how vastly hugely mind-boggling big it is. I mean you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.’”

Indeed, space is so large and vast, that the human mind cannot even comprehend the distance from the Earth to the Sun, much less to another Star.

Still, scale models help, and so do some helpful analogies.

Let us begin with the Speed of light. To our eyes light travels so fast that it appears to be instantaneous, but of course it just travels amazing fast (in fact faster than anything else can travel). Light moves at roughly 3,000 Million meters per Second, which is fast enough to Travel around the Earth about 7500 times in one second! And yet it takes light a full 8 minuets to travel from the Sun to Earth.

Let us also look at a scale model to give us a feel for the size of the Sun compared to the Earth, as well as distance. In our model we will say the Sun is the size of a Grapefruit (you can hold it in your hand). In this model the Earth is the size of a ball point in a pen and is 15 meters from the Sun, while Jupiter (the largest planet) is still just the size of a Marble. Pluto (the furthest “Planet”) is 600 meters from the Sun, and that would still not even be the edge of the Solar system! If we were to place the next nearest star in this model, it would be 4,000,000 meters away from the Sun!

Just in case your mind still needs more boggling, let us look at the amount of time we believe has passed since the Universe first came into existence. For this model we will compress all this time into the Span on one Year, and examine the dates things happened. So if we say the Universe Began promptly at Midnight of January 1st, the Earth then formed in September! The Dinosaurs Evolved just after Christmas, and quickly passes away about 4 days later! Humans didn’t evolve until 9pm on December 31st, and the Pyramids were built just 11 seconds ago!

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