The solar system really IS too big for us to imagine. It is FAR more than 9,000,500 miles. From the Sun to the Earth is about 93,000,000 (93 million) miles, or 1 A.U., as the original answerer pointed out. The average distance from the Sun to Pluto is much larger, about 40 times that Sun to Earth distance (or, 40 A.U.'s). In miles, the Sun to Pluto distance is usually cited to be around 3.7 BILLION. That's 3,700,000,000 miles..... Wow.

To give an idea of how IMMENSE the number of miles from the Sun to Pluto is, think of it this way: if you were going to start from 0 and count once per second, it would take you nearly 120 years to get to 3.7 billion. Or, how about this: if you wanted to drive to Pluto at a typical highway speed of 60 miles per hour, pack a few extra snacks, because it's going to take you about 7 thousand years. Pretty amazing.

BUT... the question is really asking about the distance to the "edge" of the solar system. Sun to Pluto is not really the size of the solar sytem; the solar system extends far beyond the planets. There are comets that are known to reach almost 1,000 A.U.,s from the sun. That's approaching 25 times farther out than Pluto, somewhere near 90 billion miles. This area is considered to be one valid "edge" of the solar system, and is called the heliopause.

Another valid "edge" of the solar system is called the Oort Cloud, but it's more controversial and questionable. Still, I believe most professional astronomers accept its existence. The Oort Cloud extends to about 2 light years, nearly halfway to the next closest star. In miles, that's between 11 and 12 TRILLION. 12,000,000,000,000 is a number whose magnitude is almost literally incomprehensible. To count that high, one number per second, would take 380,000 years.