Question

Halley’ comet was first observed in 240 BC by ** astronomers and was also in the sky in the year 1066 AD at the Battle of Hastings. Calculate the number of years that elapsed between these dates and determine how many times this comet reappeared in this interval of time, given that its ** of revolution is 76 years but excluding the appearance at 240 BC.

Answer 1

Years between 240 BC and 1066 AD = 240 + 1066 = 1306 y

Number of reappearances of Halley’* comet: 240 BC, 164 BC, 88 BC, 12 BC, 64 AD, 140 AD, 216 AD, 292 AD, 368 AD, 444 AD, 520 AD, 596 AD, 672 AD, 748 AD, 824 AD, 900 AD, 976 AD, 1052 AD 16 reappearances excluding 240 BC and 1066 AD

17 reappearances excluding only 240 BC

Note: The ** of Halley’ comet cannot be 76.0 years because it arrived in 1052 AD or 14 years before 1066 AD. Therefore, the **** of Halley’ comet must be increased by an increment Δt = 14/17 = 0.82y

Check: 17 × 76.82 = 1305.94y

1305.94 - 240 = 1065.9AD