So, we did a "science project" today, the kids and me. We made a scale model of the Solar System, out on the street, to get a visual impression of its true size. It was pretty amazing. It's a very easy project to do, takes a couple hours, and it's a lot of fun.

The Sun was a regular soccer ball, 23 cm (9") in diameter. Everything else was made to scale.

Mercury was a tiny 0.8 mm grain of sand, barely visible, about 10 m (30') away from the Sun.

Venus was a larger 2 mm grain of sand, 18 m (54') away from the Sun.

Earth was a slightly larger 2.1 mm grain, 25 m (75') away from the Sun - it was pretty mind boggling to see just how small the Earth really is, and how far away from the Sun. The Moon was even smaller than Mercury, 0.5 mm - barely visible speck of dust - 7.5 cm (3") away from Earth.

Mars was a 1 mm grain of sand, 37 m (100') away from the Sun.

Jupiter was a 2.3 cm (1") large marble. We had to walk 135 m (400') from the soccer ball to keep things at the correct scale. At this point we had to take a turn around the corner, and we "reached Jupiter".

Saturn was a slightly smaller 2 cm (0.8") marble. At 230 m (700') from the Sun, we had to walk a couple blocks to locate the planet.

Uranus was an 8 mm (1/3") peanut. Distance to the Sun: 470 m (1/3 of a mile), near Peet's cafe on the corner at the shopping center.

Neptune was also around 8 mm (1/3") peanut, 750 m (half a mile) away from Sun. We had to walk all the way to the kids' school to "reach Neptune".

Pluto and Charon are two very tiny, barely visible grains of sand, 0.3 mm and 0.2 mm, 1 km (2/3 of a mile) away from the Sun - right in the middle of the park near the school. The Pluto / Charon distance is 3 mm.

The speed of light in this scale model is 5 cm/sec (2"/sec) - the speed of a large ant, running. It takes light (the ant) 3 minutes to go from Sun to Mercury, 5 min to reach Venus, 8 min to Earth, 13 min to Mars, 45 min to Jupiter, 74 min to Saturn, 1.5 hours to Uranus, 4 hours to Neptune, and 5 and 1/2 hours to Pluto. Of course, we walked faster than light, just like a Star Trek starship. :)

The nearest star, Alpha Centauri, at 4.3 light-years, would be another soccer ball, just a tiny bit bigger than the Sun, located in... Greenland (we're in California). That totally blew my mind. So, an ant would go from California to Greenland in 4 years and 4 months. Yup, figures.

The Solar System is really, really huge - but it's nothing compared to the rest of the Universe.