On Thursday, March 20, we celebrate the vernal equinox—the first day of spring, when neither the Earth's south pole nor its north pole is tilted away from (or towards) the sun, and the day's 24 hours are split evenly between dark and light all across the globe. On the occasion of the spring equinox, daytime and nighttime carry equal weight.
In 1845, five years after Dr. J. W. Draper captured the first photograph of the full moon, French physicists Leon Foucault and Louis Fizeau made the first successful photograph of the sun. In a major technological feat at the time, the pair pointed their camera at Earth's star; after an exposure of just 1/60th of a second, the photo was made. Working with similar tools as Draper, the duo created a daguerrotype about 4.7 inches in diameter.
The naked eye, of course, cannot see the sun in all its glory during the day, but instead witnesses, at best, partial bursts at sunrise or sunset. To see the entire, brilliant sphere at once, as the early viewers of Foucault and Louis Fizeau's 1845 picture did, was an utterly new experience for most. More than 160 years ago, their seemingly simple black and white photo was remarkable for depicting our sun not as an overwhelming, ungraspable celestial body, but as another star in the sky. Our star in the sky. Visible on its surface are sunspots — areas of intense magnetic activity that are also impossible to see with the naked eye.
Just shy of 20 years after Nicéphore Niépce created the first photograph ever — an image of the French countryside, taken from a window -- humanity turned its attention, and its cameras, to the task of capturing what our unaided eyes could not see.
Today, as the plane of Earth’s equator passes the center of the sun, and our planet’s axis is in rare, momentary equilibrium, we mark the changing of the seasons -- and look toward brighter days ahead.
Erica Fahr Campbell is an associate photo editor at TIME.