Comets attract the attention of astronomers no less than planets and their satellites. It would seem that their structure and chemical composition is uncomplicated. And yet, there is one such object that you have probably heard about as well – it is Halley’s comet, which has many unique properties, and above all, is famous for its long braid, which was once thought to lead to the Apocalypse. What is Halley’s comet? Read on!
The first mention of the comet comes from China and is dated to around 240 BC. The ancient Greeks and Babylonians also wrote about it. Active studies of the cosmic object date back to the late 17th-early 18th century, when Edmond Halley predicted the passage of a comet near our planet in 1758. Based on precise observation of the celestial body, the astronomer determined that the comet’s period of circulation around the Sun is about 75 years, and its orbit is inclined to the ecliptic at an angle of 163 degrees, which implies a motion opposite to that of the planets around the Sun.
In 1910, Halley’s comet approached Earth at a fairly short distance. This made it possible to take the first photo of the object and obtain spectral data on its composition. In total, more than 600 materials were obtained. The comet intrigued with its long braid, which periodically passed by Venus and the Sun. At the same time, the approximate dimensions of the object reaching 15 km were determined.
During the examination of the chemical composition of the comet, carbon monoxide and other poisonous substances were found in it, which greatly alarmed the world community. Even more alarm was aroused by another not inconsiderable fact: the Earth was to pass through the comet’s pigtail, containing poisonous elements. Newspapers spread apocalyptic visions of deadly cyanide pouring from the sky and people fleeing in balloons into space. Scammers sold various antidotes to the poisonous substances, and some hid in barrels of water altogether.
Scientists quickly debunked these myths, explaining that the comet’s pigtail consists of dilute gases that cannot adversely affect human life. On top of that, geophysical observations showed a negligible amount of poisonous substances in the atmosphere.
In 1986, Halley’s comet made another appearance. This time astronomers were better prepared and sent several probes towards the celestial body, which analyzed the object’s composition in quite some detail. It turned out that the comet’s nucleus was similar in shape to a potato tuber with a mass of 1.4×1014 kg! The comet’s braid originally consisted of ice, but as it approached the Sun it lost its matter. The cloud of gas was about one hundred thousand kilometers in diameter.
According to optimistic scenarios, Halley’s comet will once again approach Earth around 2061. This is expected to happen in the summer, during which the wandering celestial body can be accurately seen. However, this forecast is subject to a margin of error that ranges from a few months to as much as five years. In the worst case scenario, the comet may not arrive until several hundred years from now. This could happen if the object collides with any celestial body.
main photo: unsplash.com/Jeremy Thomas
