Written for the KidsKnowIt Network by: Gemma Lavender, MPhys, FRAS
If you asked your teachers, parents or friends to name a comet, then they are very likely to answer with one of the most famous: Halley’s Comet. Astronomers believe that this well-known object has been noticed since 240 BC, however, it made its most famous appearance in 1066 AD just before the Battle of Hastings. If you lived around this time and you saw a comet in the sky, then you are likely to have been very scared of it as it appeared without warning and disappeared just as quickly from sight. You, your family and friends would have known very little about such an object, possibly believing that it was sent as a horrible present from the gods. This is exactly how King Harold of Wessex felt about the comet, seeing it as a sign of his defeat before he and his army went into battle with the Normans in Hastings. However, William the Conqueror, who led the Normans, saw it as a blessing and thanked it for his victory over King Harold’s Saxon army. The story of how Harold became defeated was woven into the Bayeux Tapestry - if you are ever in Normandy, maybe you can pay a visit to the Musée de la Tapisserie de Bayeux to see it!
You might be wondering; why Halley’s Comet as a name? Perhaps you have some ideas of what you would have called the comet if you had been living in ancient times. Just how the unwanted present of doom came about its name began in 1705. The English astronomer Edmond Halley was very interested in the comet, which he saw in 1682, and using the laws of gravity discovered by his friend, Sir Isaac Newton, he realized that he could predict when it would return. After being told that a similar comet had appeared in 1531 and 1607, he suspected it was the same comet that he had seen and set to work figuring out the next time that the comet would visit the inner Solar System. Halley worked out that the comet would make its appearance every 75 to 76 years and hoped to see it again in 1758. Sadly, this was not to be as the scientist died in 1742. However, he was correct about the comet’s return and it appeared on Christmas Day, 1758 - just in time for the festivities!
Images courtesy of NASA
No longer seen as a bringer of good and evil and named after Edmond Halley, Halley’s Comet made its last appearance in 1986 - quite a few years before you were born! You might, however, have members of your family that would have been old enough to see it streaking across the sky. If you asked them to describe what the comet looked like, then they are very likely to mention a head and a tail. Halley’s Comet, is made of a large lump of ice, dust and gas. When it approaches the Sun, after it’s long journey from outer space, Halley is warmed by the Sun and becomes bright, showing off its luminous head and magnificent tail. If you followed the comet on its journey into outer space, you would find that it would get very cold and the comet’s bright head and tail would disappear as it is not being kept nice and toasty by the Sun. Many people say that Halley’s Comet looks like a dirty snowball or a ‘hairy star,’ but you can decide for yourself when you will have the chance to see it in 2061, when it passes by the Earth.
The meteors of the Orionid meteor shower are actually chunks of debris left over from visits made by Halley's comet. This meteor shower originates from the Orion constellation area of the night sky. This is how it got its name. This meteor shower usually takes place in October every year.