Looking back: The Sky at Night
On the 25 May 1986 episode of The Sky
at Night, Patrick Moore looked at the latest results from the Giotto spacecraft, which few past Halley’s Comet on 14 March that year.
The comet orbits around the Sun once every 75 years, and in 1986 it passed through the inner Solar System – the frst such close approach since the start of the space race. To take advantage, an armada of fve spacecraft was launched to explore the comet, including ESA’s Giotto.
The spacecraft passed just 1,373km from the comet nucleus. At this distance, it was bombarded by dust from the comet, and one large impact sent the spacecraft spinning just 7.6 seconds before closest approach. Thankfully, Giotto recovered, and was able to take the frst close-up images of a comet nucleus, revealing the comet as peanut shaped and roughly 15km in length.
Giotto analysed the composition of Halley’s Comet, fnding it was largely the same as the solar nebula. This implied it was a primitive body that had remained relatively unchanged since the beginning of the Solar System.
Giotto (inset) unlocked mysteries about the size and shape of Halley’s Comet