ISON: So much for being a secret

daryllyn

new_here
reply to post by parad0x122

 

So here ya go: ISON, intact, was to pass 40,000,000 miles from Earth on its exit path from the Solar System. Now it's dispersed into a 'debris cloud' right? What is the diameter of this debris cloud, and what size are the 'pieces' contained within? I am asking because I wonder if the center of the debris cloud will still pass us at 40,000,000 miles away, and if so, how close will the outermost/closest perimeter of this debris cloud come to us?

The part of ISON's orbit that we will pass through in January is only dust. Its the pre-perihelion part of ISON's journey.

The part with the 'debris cloud' from the fragmentation so many are talking about, is the post-perihelion portion of her journey, which will be a whopping 40,000,000 miles away at its closest point to earth. Its so far above the ecliptic that there is nothing to worry about in that regard.

The most that will happen is maybe a few extra shooting stars in the sky around that time, but astronomers say that even that isn't too likely, and that we shouldn't expect to notice anything.

I recall the 40,000,000 miles as referring to the orbital prediction of the intact comet. The cloud, being larger than the comet by nature of dispersion, will have a closer approach to the Earth IF it remains on the same path as its previous incarnation, Comet ISON. My question is not about worry or perihelion or how many shooting stars. My question is HOW CLOSE will the perimeter of this expanding cloud of the remnant of ISON come to Earth. ***Bonus points if you tell me both the current and projected diameter of the cloud (whilst closest to Earth.)

reply to post by new_here

See, I remember reading (initially) that Earth would pass thru the tail of then-intact-ISON after its closest approach of 40,000,000.

There is a lot of confusion over that.

In mid January (not December, when the remains will be "closest" to Earth), the Earth will be at the point of its orbit where the comet was in early November. However, at that time the comet was above the ecliptic (Earth's path) and, as we know, the tail was pretty insignificant at that time. Earlier this year it was thought that if the comet had lived up to early enthusiastic prognostications, we may have passed through the fringes of its dust tail. Pretty unlikely that will happen, but in any case it has nothing to do with what the comet has done since November 2nd.

Phage
reply to post by new_here

 

See, I remember reading (initially) that Earth would pass thru the tail of then-intact-ISON after its closest approach of 40,000,000.

There is a lot of confusion over that.

In mid January (not December, when the remains will be "closest" to Earth), the Earth will be at the point of its orbit where the comet was in early November. However, at that time the comet was above the ecliptic (Earth's path) and, as we know, the tail was pretty insignificant at that time.

Gotcha. That makes sense (although I thought I saw that tail fire up in November (online images) but I'll take your word for it.)

Still... have you seen any reference to the diameter of the dust-cloud and/or the closest its perimeter will be to Earth in December?

reply to post by new_here

I haven't.
But a paper napkin calc says that the particles would have to have a velocity of about 60,000 mph relative to the original orbit to reach a distance of 40,000,000 miles by the time the center passes (above) Earth's orbit.

That's a whole lot of what's known as delta v (change in velocity).