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Does anyone know if this Comet is mentioned in the Gemara? There are comets mentioned in the Gemara a number of times. As we know many Amoroim were well versed in astronomy. I think there is a Gemoroh that speaks of a comet that comes every 50 years or so, just wondering if this comet (due to be seen on 3rd Dec) is mentioned?
No it is not. this is a long period comet which appears to be on its first (and probably only) trip into the inner solar system. If it survives Perihelion (Closest approach to the Sun) it will be flung into the far depths of the solar system and probably out all together.
The thing is comets are balls of Ice of various types, so when they pass close to the sun they sometimes break up.
Comets are mostly unpredictable, there are a few 1p/Halley, 55p/Temple-Tuttle that come by Earth on more or less regular periods, that generally run from 20 to 200 years most comets are what are known as Long Period comets that have orbits that run from 100,000 to millions of years. Most of them are unpredictable, we often only know about them a year or so in advance when someone catches them on a survey of the outer solar system.
The community keeps an eye out for them for several reasons, many people are just passionate about finding comets, but also more importantly there is a small but real chance that a comet or astroid could hit the Earth and do real damage. Comet Shumaker/Levy 9 hit Jupiter about 20 years ago and we think a 2-3m rock from space probably hits the Earth about every 10 years or so. Now depending on where that hit it could do a lot of damage, so we try to know about it in advance.
Having done a little more research on this, 1/p Halley is the only short period comet that is visible without some form of optical aid. So while there are a lot of known SPC’s, all the others would require at least Binoculars if not a telescope to see. Actually for a Comet a 7×50 Binocular will be better then a telescope most of the time.
That being said Bright Comets seem to show up about once every 5-10 years or so. But those are generally long period comets that we only know about when someone spots them as they head into the solar system.
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