When will Haley's Comet visit Earth again?

Distant greetings from Halley's Comet

In 1986, Halley's Comet presented itself as a bright celestial object with a fascinating tail on its near-Earth crossing of the inner solar system and was easily visible to the naked eye. Its appearance today is less impressive: the new image shows the 10-kilometer cometary core made of ice and dust as a weak point of light without any sign of activity.

Even if the image seems unsatisfactory at first glance because of its low resolution, the image taken by the VLT is something very special: never before had it been possible to observe a comet so far away. ESO reports that it has never been possible to make such a dark object visible. Halley's comet only reflects about 4 percent of the light it hits, and at its current position, the incident sunlight is about 800 times weaker than the light shining on Earth.

On its orbit around the sun, the comet is currently on its way to the most distant point. It will not be within sight of the earth again until 2062. This regular recurrence every 76 years is recorded until 240 BC, with the exception of the apparition from 163 BC. During the 1986 visit, the comet could be examined at close range for the first time: two Japanese probes collected data from further away, the two Russian probes Vega 1 and 2 approached less than 10,000 kilometers, and the European Giotto probe passed the nucleus in one Distance of 605 kilometers.

ddp / bdw? Ilka Lehnen-Beyel
September 3, 2003

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