The summer solstice is upon us: Monday, June 20, will be the longest day of 2016 for anyone living north of the equator. If pagan rituals are your thing, this is probably a big moment for you. If not, the solstice is still pretty neat. This year’s even includes a "strawberry moon," the first time that’s happened since 1967. Below is a short scientific guide to the longest day of the year (though not, as we’ll see, the longest day in Earth’s history — that happened back in 1912).