Wednesday, 29 September 2010

Numbers I can understand....

Two days ago when I was writing about bright Jupiter in the night sky (drat, it's still rainy nights where I am), it suddenly dawned on me that I have little understanding of how far the planets are from the sun, or from us here on Earth. I know they are in millions and billions of kilometres but I cannot simply fathom those astronomical numbers:
Mercury : average distance 58 million km (46.0 to 69.8 million km), Venus : average distance 108 million km (108 to 109 million km), Earth : average distance 149.6 million km (146 to 152 million km), Mars : average distance 228 million km (205 to 249 million km), Jupiter : average distance 778.5 million km (741 to 817 million km), Saturn : average distance 1.43 billion km (1.35 to 1.5 billion km), Uranus: average distance 2.88 billion km (2.7 to 3 billion km), Neptune: average distance 4.5 billion km (4.46 to 4.54 billion km) 

Mind-boggling numbers. Just like I cannot imagine the size of a room that holds one million pieces of RM1 currency notes, I cannot picture a distance of 4.5 billion kilometres. How about you? How can I measure 4.5 billion kilometres in Earth terms? But luckily, someone pointed me to a comparative measurement of these distances. Now, here are numbers that I can really understand..... 
Imagine if we hold up a big yellow grapefruit representing the Sun. Mercury will be a small grain of salt about 5.5 metres away, Venus will be like a grain of sugar 10.4 metres away, Earth is another grain of sugar located 15.2 metres away, Mars is the size of a grain of salt 22.9 metres away, Jupiter a cherry-sized tomato at 73.2 metres, Saturn the size of a green grape at 128 metres, Uranus a frozen green pea at 274.3 metres and Neptune also the size of a frozen pea at 429.8 metres. Pluto, now not considered a planet, will just be a speck of dust at a distance between 434.4 and 548.6 metres from the grapefruit.

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