No, it’s likely just full of steel, though some modern horseshoes are made of synthetic materials. Any luck experienced around a horseshoe, no matter its composition, is purely coincidental. http://en.wikipedia.org/wiki/Horseshoe
Not on your life. While some lemmings may die during mass migrations, they’re not suicidal. The myth that lemmings commit mass suicide when overpopulated was popularized by the 1958 Disney documentary White Wilderness. http://www.snopes.com/disney/films/lemmings.asp
Is Pluto still a planet?
Technically no. In 2003, a International Astronomical Union downgraded Pluto’s status from “planet” to “dwarf planet,” which is defined as an object that’s held in orbit of the sun by gravity but that is too small to clear other objects from its region. http://www.loc.gov/rr/scitech/mysteries/pluto.html
Does the moon have a man in it?
The moon’s had a man on it at various times, but never in it. The traditional story about a man in the moon is thought to have been inspired by the shapes of darker lunar maria, or “seas,” as compared to the lighter lunar highlands. http://en.wikipedia.org/wiki/Man_in_the_Moon
It’s a thing, just not a real one. Scientists have found that bacteria doesn’t wait a considerate five seconds before boarding your dropped potato chip, but will cling to food immediately. http://en.wikipedia.org/wiki/Five-second_rule