Is it possible for Neptune to cast a shadow on Pluto / vice versa?

Answer 1

In theory yes, but the distance between the two is so great that the so called core of the shadow (the only part of shadow we can notice, won't reach each other.

Answer 2

In spite of concerns whether Neptune or Pluto can completely occult the sun due to size and distance issues, Pluto will never even be seen to transit the sun's disk from Neptune. The two are in an orbital resonance, which means when Pluto is inside of Neptune's orbit, Neptune is far away in a different part of its orbit. Furthermore, if you look at viewgraph #2 of the source link, you will see that Pluto is high above the ecliptic when it is at perihelion.
This is why Pluto's orbit is reasonably stable and it has not been ejected or fed into the inner solar system through an interaction with Neptune.

The other question is a bit dicier, but I do believe that Pluto's highly inclined orbit will make a transit of Neptune across the face of the sun highly unlikely.

Answer 3

I don't think so. For the first thing, (and I can not be sure of this one) I think that the only times Pluto is crossing the plane that Neptune orbits the sun, Pluto is actually closer to the sun than Neptune. I could be mistaken on that and hopefully someone else can confirm it for us.

But for the sake of arguement, let us assume that Pluto is farther from the sun than Neptune....

Then it would still not cast a shadow, at least not in the conventional sense. If you were on Pluto, you would see the sun as a larger object than Neptune.
The math is pretty simple, all you need to determine their angular size is the diameter of the sun and neptune and thier distances from pluto. The final answer will vary a little depending on what values you use, but in the end you will find that the sun appears in the sky of Pluto to be about 6 to 7 times larger than Neptune.
You would certianly notice if Neptune transited across the face of the sun and there might be a noticable dimming from the penumbra, but you won't see anything like a total solar eclipse.
We, here on earth, see Mercury and Venus transit across the sun on many occasions. Granted Mercury and Venus are nowhere near as large as Neptune would appear to be against the sun. but I suspect that if you were on Neptune and saw Pluto pass in front of the sun, it would be about as noticable as it is for use when Mercury does. i.e. you wouldn't know about it unless someone told you.



Additionally, because Pluto's orbit is inclined so much, it is only in the same plane as Neptune at two points, and both planets would have to be in exactly the right spots for this kind of event to occur.

I'm sorry I can't give you a definative answer, but I hope this helps.
So to answer your question, it is possible. But not likely, and if it ever did, you might not even notice.

Answer 4

Neptune cant cast a shadow on pluto, but it can surely cast a shadow on uranus.