from Wikipedia 1 pc = 1AU / 1" = 1AU / (2π/(360 x 60 x 60)) 149 597 870 691 ± 30 m = ----------------------- 4.8481368110 E-6 = 3.08568 r×10^16 m(petameters = 10^15 m) cf.) 1 apc(atto-parsec) = 3.08 cm 100,000 AU --- 1.6 light years --- Outer radius of Oort cloud 210,000 AU --- 3.2616 light years (3.08568×10^16 m) --- 1 parsec 9.5 × 10^20 m --- 100,000 light years --- Diameter of the disc of the Galaxy 4.7 × 10^24 m --- 500 million light years --- Length of the Great Wall, the largest observed superstructure in the universe. 1.3 × 1026 m --- 13,700 million light years --- Distance to the cosmic background radiation; radius of the observable universe. 5.9 × 10^26 m --- 62,000 million light years --- Cosmological event horizon: the largest comoving distance from which light will ever reach us (the observer) at any time in the future. --- 13.7 billion parsecs, hence once my temporary, quite pretentious, signature: "Listen to the sound from billions of parsecs away, Everything is its reverberation." *-------------------------------------------------------* The light that burns twice as bright burns half as long. And you have burned so very very brightly, ... -- Tyrell -- *-------------------------------------------------------*