I've watched the Venus transit 2004 with a small telescope, a relatively rare event, considering most people can only observe two in their life time.

If E.T. were sitting in a sunny place on a moon of the outer planets, sipping on a liquid nitrogen drink, would there ever be (has there ever been) a transit of an inner gas giant?

I guess if E.T. were in Sputnik Planum, there would be no transits due to Pluto's orbital plane being inclined too much wrt. the Ecliptic.

  • $\begingroup$ Pluto's orbit does rise above and below (from a looking at the solar-system as a disk) point of view, so it's always possible that you could catch a planet in transit from Pluto's orbit. All the planets have tilted orbits, so that would be a problem from every planet, though more so from Pluto. The real problem is, as you get further out the sun takes up less and less of the sky, so it goes from the golf-ball size object that we see in the sky, to a pea around the distance of Saturn, to an apple seed from Neptune, and so on. The less sky the sun takes up, the more rare a transit becomes. $\endgroup$
    – userLTK
    Sep 26, 2015 at 13:36
  • $\begingroup$ There are plenty of points in space you could see an outer planet transit the Sun, but you are limiting this to planets and their moons, is that correct? Also, if you're on a planet's moon, transits by the planet itself don't count? $\endgroup$
    – user21
    Sep 26, 2015 at 17:05

1 Answer 1


Wikipedia actually has many pages on this subject. Transits of Jupiter, viewed from Saturn are rare. The calculations are done from the centre of the planet, rather than a moon, but the principle is clear: Transits of Jupiter are rare.

The next, non-grazing transit of Jupiter visible from Saturn is in 7541. From Uranus in 2714, and from Neptune in 2188.

But probably the most photogenic transit will be the transit of Saturn from Uranus in 2669.

Saturn will also transit from Neptune in 2061, the only transit which we could live to see. Uranus will not transit from Neptune until 38172, and transits from Pluto or other KBO are even more rare, due to the high orbital inclinations.


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