The Planets 1

Our solar system is huge. There is a lot of empty space out there between the planets. Voyager 1 the most distant human-made object, has been in space for more than 25 years and it still has not escaped the influence of our Sun. As of July 19, 2004, Voyager 1 was about 13,800,000,000 km from the Sun - more than twice the distance from the Sun to icy Pluto. Needless to say, our solar system doesn't fit real well on paper - or a website for that matter.

Scientists figured out a while ago that writing out those huge numbers wasn't the best use of their time so they invented the Astronomical Unit (AU). One AU - 150,000,000 km represents the average distance from the Sun to the Earth. It would take an airliner more than 20 years to fly that distance - and that's just a one-way ticket.

(That's traveling at about 644 km per hour.) In another effort to bring these vast distances down to Earth, we've shrunk the solar system down to the size of a football field. On a football field scale, the Sun is about as big as a dime. Considering a typical honeybee is about 12 mm long, the fans are going to need telescopes to see the action.

The inner planets - Mercury, Venus, Earth and Mars - are about the size of grains of sand on a football field scale. A typical flea would dwarf them, which is about 3 mm long. Closest to the goal line is Mercury, just under a yard from the end zone (.8 yards to be specific). In reality, the average distance from the Sun to Mercury is roughly 58,000,000 km (35,000,000 miles) or 0.4 AU. At this scale, Mercury's 0.06 mm diameter is scarcely as large as the point of a needle.

Venus is next. It is 1.4 yards from the end zone. The true average distance from the Sun to Venus is about 108,000,000 km (67,000,000 miles) or 0.7 AU. Its size on this scale is about 0.15 mm. On to Earth, sitting pretty, on the 2-yard line. It is slightly larger than Venus at about 0.16 mm.

Just as most quarterbacks would be extremely pleased to find their team within two yards of a touchdown, Earth reaps many benefits from this prime location in the solar system. We are at the perfect distance from the Sun for life to flourish. Venus is too hot. Mars is too cold. Scientists sometimes call our region of space the "Goldilocks Zone" because it appears to be just right for life. As noted earlier, Earth's average distance to the Sun is about 150,000,000 km (93,000,000 miles) from the Sun. That's 1 AU.

Next- Planets part2