Image of the Day: A Mesmerizing Cloud of Interstellar Dust

The astronomer Carl Sagan famously called Earth a “pale blue dot,” but it originally came from a bright blue cloud. This glowing blob of light is what astronomers call a “reflection nebula.” It’s a giant cloud of interstellar dust, lit up by the glow of a nearby star — here, it’s Merope, one of the brightest stars in the Pleiades constellation, also known as the Seven Sisters. The dust grains in question are mostly carbon, the same substance that, in the form of carbon dioxide, is trapping increasing amounts of the Sun’s heat as humans burn more and more fossil fuels.

The fact that carbon exists both on Earth and in interstellar space is no coincidence. Like most of the other elements our planet is made of, including iron, silicon, nitrogen and oxygen, carbon is forged in the thermonuclear fires inside stars. Most of the substance of our bodies, our houses, our technology — and of the fossil fuels we’re now burning at an unsustainable rate — were once literally in center of a long-dead star. When the stars finally die, these elements are blown out into space where they form into huge clouds, trillions of miles across. Eventually, the clouds collapse to form new stars, and with them, planets and people.

Credit: Leonardo Orazi