As I said in another comment[1] this is only true at small scale. As soon as you start crossing oceans, you absolutely do not want to navigate in straight line as it's going to inflate your travel by a significant amount of distance.

As such, while the Mercator projection makes total sense for a map of northern Europe or the Caribbean, it makes absolutely no sense as a map of the entire world.

[1]: https://news.ycombinator.com/item?id=45002873

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luckylion 13 hours ago | parent [-]

Did they have better map projections for cross-oceanic navigation 500 years ago when the mercator projection was invented?

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littlestymaar 10 hours ago | parent [-]

AFAIK you'd need a projection for each origin/destination pair, so it's not exactly convenient. A globe is by far the best tool for such a job.

	▲	luckylion 4 hours ago \| parent [-]
		But globes aren't really that practical for navigation. You can plan your voyage, but when you're at sea, how do you make sure you're going in the right direction? Mercator has the advantage that you can use your compass and as long as you stay on course, you'll arrive at your destination. Keep in mind: that's 500 years ago, not 50 years ago. There's no question that we have better tools today but the question was why the mercator projection was so successful it became the default. I think "it was super useful at the time because it made navigation easy, reliable, and available to everyone, at any any weather" is a much more compelling explanation than "the would-be colonizers spread it because their home-countries were enlarged and they liked that and used it to oppress the equatorial countries".