If ISON was travelling several times faster than Voyager is, then why will it take 40k years for Voyager to reach the end of the Oort Cloud, but the ISON orbit is like 200-300k years from one end to the other?

You have to compare the speeds at the same distance from the sun to make a proper comparison. ISON, at a distance of ~48,000,000 km form the sun is moving at ~74 km per sec, while Voyager 1 is moving at ~17 km/s at a distance of ~1.9X10^10 km from the Sun. Objects gain speed as they fall in towards the Sun and lose it as they climb away.

 

If you calculate how fast ISON was moving when it is was the same distance from the Sun as Voyager is now, you get an anwer of ~8.5 km/s, which is slower than what Voyager is moving at that distance.

that's the only explanation i thot there could be, but didn't want to manipulate answers by stating it in my post.

 

i'm a genius!!! (amongst my friends n fam)

 

thx for the answer Janus.