Nine years ago, the New Horizons space probe was launched, and one of its targets for exploration was, at the time, billions of miles away from Earth. That target was Pluto, and at the time of the launch, Pluto still was considered a planet. But even though Pluto has been downgraded, the expected “arrival” of New Horizons, which will come within an estimated 7,800 miles of Pluto at around 7:49 a.m. ET, is an exciting scientific achievement. Already, detailed photographs relayed from