How large is halley's comet

Question

What would the length of the tail be? If it's orbit is further than plutos and we can see it this must be a h**l of a comet, and how fast is it traveling at in mph?

Answer 1

During 1985-86 when Halley came,several space crafts tried to go near and collect information.Giotto by ESA was the best to reach about 500 kilo meters from Nucleus of Halley.

The Nucleus was about 14kilo meter long and may be about 8kilo meters wide. The tail  is produced by the sublimating ice materials and the amount and length depends upon the distance from Sun. The solar wind blows out the tail and it may be millions kilometers.

Answer 2

It is actually quite small and loosely built, not that dense.  It is 15 kilometers long and 8 kilometers thick and shaped like a peanut.  The extraordinary brightness is due to ice and snow being melted and spewing off of the comet in a long trail that is very reflective which makes haleys comet so bright.  The comet itself is jet black.  Because of its crazy orbit, haley goes very fast at almost 160,000 mph.  

Answer 3

The nucleus is the size of Manhattan. The length of the tail depends on how close a pass to the sun it makes, and it only shows a tail when it's in the inner solar system because the increased heat causes the outgassing. Typically for "bright" comets, the tails would be a few  million to a few tens of millions of miles long.

Halley does go as far as the orbit of Pluto, but not at Pluto's greatest distance from the sun, and it can only be seen now through large telescopes. The speed changes because the orbit is very elliptical. Right now, it's slowing down because it's close to it's furthest distance from the sun, but it won't reach that point for another 15 years.