Gazing up at the sky, it’s hard not to imagine the sun, moon, stars, and planets as part of an inverted bowl over our heads, even if we know that’s an antiquated way of viewing the heavens. These days, we understand it’s the Earth that’s spinning, spinning daily like a ballerina while also circling the sun on its yearly journey. But the bowl imagery was and remains a reasonable way of envisioning how the skies appear to revolve around us, and when certain stars appear or disappear with the changing hour or season.
But to understand the universe as it really is, we need a three-dimensional picture of the skies. The Copernican revolution started this change in perspective, but it took until the 20th century for a true understanding of the universe’s scale and layout to evolve.
