250,000 years
Halley's comet is visible approximately every 76 years.
once roughly every two years
A horse in the wild will grind his teeth down by eating forage. When you have a domesticated horse you should have your horses teeth floated every one too two years. If you don't then the horse teeth will become like needles stabbing them in the mouth every time you ride.
Every child is different, but by the age of 2 and a half all baby teeth should be visible.
If the one pack a day smoker has a habit for 40 years, that would come to 20 cigarettes X 365 days per year X 40 years. If that smoker had a two pack a day habit, then the answer would need to be doubled.
12 years
86.9 years
Approximately every 76 years 1986 + 76 = 2062
He apparently was a smoker at the time he was on the American Idol show and tour 6 years ago. I am not sure if he has quit since then or not.
He has often been seen in candid photos over the years smoking cigarettes. As of September 2012 he was still a smoker.
Halley's Comet is a well-known comet that orbits the Sun approximately every 76 years. It last appeared in 1986 and will next be visible from Earth in 2061.