See Effective Potential for a useful tool that lets you pretend things are just moving radially. When you have something far away and want to know its closest approach, you just need its energy (kinetic+potential) and its angular momentum. To get something to hit the sun, you don’t just need its velocity to be small, you need its angular momentum to be small, which is hard because that grows linearly with distance from the sun.
See Effective Potential for a useful tool that lets you pretend things are just moving radially. When you have something far away and want to know its closest approach, you just need its energy (kinetic+potential) and its angular momentum. To get something to hit the sun, you don’t just need its velocity to be small, you need its angular momentum to be small, which is hard because that grows linearly with distance from the sun.
Yes, but somehow large Kreutz comet came recently close to Sun, so there should be a mechanism which makes it more likely.