Here’s some New Year’s Eve astronomy trivia: I saw an article this morning noting that we’re about half-way through a period between early October 2010 and late March 2011 where “there is a short period each night when no planet is above the horizon. This brief period occurs between Jupiter and Uranus setting and Saturn rising”.
It’s an interesting piece of trivia, but just how unusual an occurrence is it?
No takers? Where have all the astronomers gone? Anne Neville?
I think this would vary depending on your latitude. It would happen far more often at the poles than at the equator.
:dubious: I don’t think you can actually point a pole away from the ecliptic.
Half the ecliptic is below the celestial equator, which is as far south as you can see from the north pole, so any time a planet is south of that, it’s never above the horizon. Reverse for south polar observers.
Just a rough idea.
For no planets to be visible they must all be on one side of the Earth at some point during the rotation. The probability of this is roughly 1 in 2^8 or 1/256. The approximations are very fuzzy (in fact my logic could be completely wrong) but if I am even close it would indicate the situation is not as rare as we might think.
Plus this doesn’t take into account that Mercury and Venus are always within a certain number of degrees of the sun which would have an impact on the calculations.
Here is a chart of the current position of the planets. (And Pluto) I don’t know how to properly describe their positions, but all the outer planets (and Mars) are in the same ‘half’ of their orbits, on the ‘other’ side of the sun from us.
Right now, the outer three planets are in about the same quarter of an orbit, but once they spread out, due to their lengthy orbits, we could go hundreds of years without this happening again.
[/slight Hijack]
this is probably been asked before, do all the planets orbit the sun on the same geometric plane, more or less?
Except for Mercury and Pluto, yes.
ETA: Mercury’s orbit is inclined 7 degrees from the ecliptic, and Pluto’s is inclined 17 degrees.
The correct answer is just Mercury … Pluto is not a planet.
I’ll never give in to Planetary Correctness!
Yeah, but at any point on the globe isn’t half the ecliptic below the horizon? It’s not like the equator is under the ecliptic looking up at it. So anywhere on the globe could have a moment where all the major planets are below the horizon. Now, if you want a longer stretch of time, maybe it would last longer at a pole, sure. But then it would occur less often, surely, as the total amount of time with no visible planets seems like it would be the same anywhere on the globe.
Am I wrong?