A nebula is a giant cloud of dust and gas in space that can consist of ionized, neutral, or molecular hydrogen and cosmic dust. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. They are made up of dust, basic elements such as hydrogen, and other ionized gases. Nebulae can form through clouds of cold interstellar gas and dust or through the aftermath of a supernova. Some nebulae come from the gas and dust thrown out by the explosion of a dying star, such as a supernova, while others are regions where new stars are beginning to form. For this reason, some nebulae are called "star nurseries".

Nebulae are often found in the space between stars, known as the interstellar medium. On average, this region contains only around one atom per cubic centimeter, but in certain places, the density can be significantly higher than this, high enough to become visible through a telescope. Nebulae can be of vast size, with some hundreds of light-years in diameter. Some nebulae are bright enough to be seen with the naked eye, such as the Orion Nebula, located between the stars in the constellation Orion’s sword.

Astronomers use very powerful telescopes to take pictures of faraway nebulae. Space telescopes such as NASAs Spitzer Space Telescope and Hubble Space Telescope have captured many images of faraway nebulae. Through advanced space telescopes like the Spitzer and Hubble Space Telescopes, we have plenty of gorgeous imagery of nebulae. Most of these are formed through infrared and false-color images, but they all are striking.