The current observable universe is about 93 billion light years in diameter. Light travels at a speed of 186,000 miles per second, 671 million miles an hour or about 6 trillion miles a year. If our sun was the size of a one-pence piece, the nearest star, Alpha Centauri, would be about 350 miles away. On this scale, our Milky Way galaxy would be 7.5 million miles across. Astronomers tell us that there are millions of galaxies so the universe is enormous and, according to scientists, still expanding.