I see this comet being chased by ESA, they said it is presently about 500 million km from the sun. That puts the radiation received by that comet at about 10% (roughly) as what we receive on Earth, well at least on top of the atmosphere, at 1355 watts per meter ^2. Looking at the size of that comet, I just rounded it out to 3000 by 4000 meters that would receive energy from the sun and at ten %, 135 watts per meter squared comes out to something like 1.5 gigawatts deposited on the surface at any given time, which of course goes up as it gets closer to the sun. My question is, given 1.5 gw hitting the comet, how much force does that represent on the comet trying to push it away from the sun and how much would the orbit be altered by that force each orbit? Could you calculate how much different the obit would be if it was orbiting say a black hole that doesn't radiate so there is no direct energy being deposited and it had a similar orbit to that comet. That force would be trying to accelerate a mass about that of Mount Everest so I know it wouldn't have a massive effect but how much would that force move the orbit from orbit to orbit? And wouldn't the orbit also be effected by the propulsion given by the ejected water when that water acts like a rocket leaving the comet, but in this case it could be aimed at any arbitrary angle. So could you calculate all those potential changes to the orbit of that or any other comet?