Voyager 1, the most distant human-made object in the cosmos, reached 100 astronomical units from the sun on Tuesday, August 15. That means the spacecraft, which launched nearly three decades ago, will be 100 times more distant from the sun than Earth is. Voyager 1 will be about 15 billion kilometers (9.3 billion miles) from the sun. Voyager 1 is now at the outer edge of our solar system, in an area called the heliosheath, the zone where the sun's influence wanes. This region is the outer layer of the 'bubble' surrounding the sun, and no one knows how big this bubble actually is. Voyager 1 is literally venturing into the great unknown and is approaching interstellar space. Traveling at a speed of about one million miles per day, Voyager 1 could cross into interstellar space within the next 10 years.