“Madness is rare in individuals, but in groups, parties, nations, and ages it is the rule.”
—F. Nietzsche, Beyond Good and Evil, §156.
"The madman jumped into their midst and pierced them with his eyes. ‘Where is God?’ he cried; ‘I’ll tell you! We have killed him – you and I! We are all his murderers.’”
– Nietzsche, The Gay Science, §125
The Voyager spacecraft a billion years from now
Earthrise, sourced from photos shot during Apollo 10’s orbit around the Moon, May 1969.
This artist’s concept puts solar system distances in perspective. The scale bar is in astronomical units, with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the sun to the Earth, which is about 93 million miles or 150 million kilometers. Neptune, the most distant planet from the sun, is about 30 AU.
Informally, the term “solar system” is often used to mean the space out to the last planet. Scientific consensus, however, says the solar system goes out to the Oort Cloud, the source of the comets that swing by our sun on long time scales. Beyond the outer edge of the Oort Cloud, the gravity of other stars begins to dominate that of the sun. The inner edge of the main part of the Oort Cloud could be as close as 1,000 AU from our sun. The outer edge is estimated to be around 100,000 AU.
NASA’s Voyager 1, humankind’s most distant spacecraft, is around 125 AU. Scientists believe it entered interstellar space, or the space between stars, on Aug. 25, 2012. Much of interstellar space is actually inside our solar system. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it.
Alpha Centauri is currently the closest star to our solar system.
Image credit: NASA/JPL-Caltech