An open letter to Galileo from Ferdinand Magellan, Sir Francis Drake and Eratosthenes:

Enjoyed Alexandra Petri’s March 28 op-ed column “An open letter from Galileo to Ted Cruz.” For us, time is now endless, so it’s nice to read something stimulating! Petri cited Christopher Columbus’s Atlantic crossings to argue the world is not flat. Our replies, first in turn, then together:

MAGELLAN: Columbus did sail, but he didn’t disprove a flat Earth. For all four New World visits, his eastward return trips essentially retraced his outbound routes, only in reverse direction.

DRAKE: Magellan’s was the first expedition to circumnavigate the globe (1519-1522). A pity he didn’t survive the voyage himself (he died in 1521). I can’t begin to describe the feeling when I survived my own circumnavigation expedition (1577-1580) to its successful conclusion!

ERATOSTHENES: I felt the world was round 2,255 years ago! In fact, I did a simple physical experiment: I compared noontime summer solstice sun angles at Syene and Alexandria (in Egypt) to estimate Earth’s circumference. Quite accurate, I’d say, given the knowledge and tools then available.

ALL: As a political polemicist, Sen. Ted Cruz (R-Tex.) is without peer in his capacity to abuse logic!

Richard Stanton Brown, Charlottesville

Alexandra Petri’s open letter brought a chuckle despite the very strained analogy between “flat-Earthers” and “global warming deniers.”

Whatever verdict on global warming, Petri made a serious error of fact that Galileo (and probably Sen. Ted Cruz) would have avoided.

Christopher Columbus did not prove the Earth was round, although that certainly was his belief. He proved there was land far to the west of Europe. Columbus thought he was going to circumnavigate the globe, but he didn’t — not because it wasn’t round, but because the Americas were in his way. He had no clue that the Indies, or the Pacific, lay even farther beyond his “discoveries.”

Leaving aside the question of whether the ancients realized Earth must be round and the evidence of Norse voyages that predated Columbus, actual proof must be ascribed to the Portuguese explorer Ferdinand Magellan. He sailed in 1519, and the voyage of circumnavigation was completed in 1522, although Magellan himself was killed in the Philippines in 1521. Since Columbus died in 1506, we can assume he knew nothing about Magellan. Galileo, however, would have known — and he might well have said of those who claimed the honor for Columbus, “This is so wrong!”

Lynda Meyers, Arlington