Halley was eventually proved correct on all counts. Although he died in , his comet appeared in the sky on Christmas night of , right on schedule. Its discovery was hailed as a triumph of scientific reasoning and Newtonian physics.
Edmond Halley only identified a handful of occurrences of his comet, but other scholars have plotted its earlier appearances and uncovered historical references dating back to the ancient world. In a paper in the Journal of Cosmology, researchers Daniel W. The celestial visitor was often considered a bad omen, and it was linked to everything from the death of kings to natural disasters. The historian Flavius Josephus described the comet of 66 A.
In , meanwhile, the Holy Roman Emperor Louis the Pious feared the comet was a signal of his downfall and tried to ward off its influence with fasting, prayer and alms for the poor. When the comet made its closest approach to the sun, it was on the opposite side of that star from the Earth — making it a faint and distant object, some 39 million miles away from Earth.
Several spacecraft successfully made the journey to the comet. This fleet of spaceships is sometimes dubbed the "Halley Armada. The European Space Agency's Giotto got even closer to the nucleus, beaming back spectacular images to Earth. Japan sent two probes of its own Sakigake and Suisei that also obtained information on Halley.
Sadly, the astronauts aboard Challenger's STSL mission were also scheduled to look at the comet, but they never got the chance. The shuttle exploded about two minutes after launch on Jan. It will be many decades until Halley's gets close to Earth again, but in the meantime you can see its remnants every year. The Orionid meteor shower, which is spawned by Halley's fragments , occurs annually in October.
Halley's also produced a shower in May, called the Eta Aquarids. When Halley's sweeps by Earth in , the comet will be on the same side of the sun as Earth and will be much brighter than in At least one study has pointed out that it is difficult to predict Halley's orbit on a scale of more than years, and that the comet could collide with another object or be ejected from the solar system in as little as 10, years, although not all scientists agree with the hypothesis.
When Halley next returns to Earth's vicinity, one astronomer predicted it could be as bright as apparent magnitude This is relatively bright, but well below that of the brightest star in Earth's sky : Sirius, at magnitude There is a group of comets called "Halley family comets" HFC because they appear to share the same orbital characteristics of Halley, including being highly inclined to the orbits of Earth and other planets in the solar system.
However, this family has a range of inclinations, which prompts other astronomers to suggest they may have a different origin than Halley. Some suggest these comets could have evolved from members of the Oort Cloud, or from Centaurs objects that generally have a closest approach between Jupiter and the Kuiper Belt. Alternatively, HFCs could have come from somewhere just beyond Neptune.
While it will be decades before we can send another spacecraft to Halley's Comet, there have several other missions that have studied comets from up close. One of its key findings was uncovering that Comet 67P had a different kind of water specifically, a different deuterium-to-hydrogen ratio than what is seen on Earth.
Back in the s, similar examinations of Halley by the Giotto probe also showed that Halley has a different D-to-H ratio in its water than on Earth. In fact, Earth's orbit carried it through the end of the comet's million-mile-long tail for six hours on May 19, earning the story the day's banner headline in The New York Times. While most reporters of the day turned to astronomers to get the facts straight, the yellow press chose to pursue the story in more fanciful ways, helping to fuel the fears of the impressionable that the end of the world was nigh.
Despite some published reports leading up to the event, the comet's tail did not contain poisonous gases, and there was never any danger of a celestial collision, either. In anticipation of the comet's arrival, telescope sales shot up, and hotels in large cities offered special packages that included rooftop viewings.
President William Howard Taft had a look-see at the U. Naval Observatory and came away suitably impressed.
0コメント