The Eagle Nebula & Pillars of Creation: Icons of Space

In 1995, the Hubble Space Telescope aimed its cameras at a small region within the Eagle Nebula, cataloged as Messier 16, and produced an image that became one of the most recognizable photographs in human history. The Pillars of Creation, three towering columns of gas and dust set against a glowing nebular backdrop, captured the public imagination like few astronomical images before or since. They appeared on magazine covers, in classrooms, on posters, and in documentaries. They became, for many people, the defining image of the cosmos.

But the Pillars are far more than a pretty picture. They represent one of the most dynamic and violent processes in the universe: the birth and death of stars happening simultaneously in the same small region of space. Understanding what you are looking at transforms the image from a beautiful photograph into a window on cosmic creation itself.

What Is the Eagle Nebula?

The Eagle Nebula is a large emission nebula and star-forming region located approximately 7,000 light-years from Earth in the constellation Serpens Cauda, near the border with Scutum. It was discovered by Jean-Philippe de Cheseaux in 1745, and Charles Messier added it to his catalog in 1764 as M16. The nebula spans roughly 70 by 55 light-years and contains a young open star cluster whose stars are only about one to two million years old, which is extremely young in astronomical terms.

The nebula glows primarily from ionized hydrogen excited by the ultraviolet radiation of the hot young stars in the central cluster. These massive O-type and B-type stars have surface temperatures exceeding 30,000 Kelvin and luminosities hundreds of thousands of times that of the Sun. Their intense radiation sculpts the surrounding gas and dust into the dramatic shapes that make M16 so photogenic.

The Science Behind the Pillars

The Pillars of Creation are examples of what astronomers call elephant trunks, dense columns of gas and dust that resist the erosive effects of intense radiation from nearby hot stars. Here is how they form: when a massive star ignites in a cloud of gas, its ultraviolet radiation begins to ionize and evaporate the surrounding material in a process called photoevaporation. Less dense regions erode quickly, but denser pockets of gas resist longer, creating elongated columns that point toward the radiation source like fingers pointing at a flame.

At the tips and along the edges of the pillars, small, dense knots of gas called evaporating gaseous globules, or EGGs, are being simultaneously eroded by radiation and compressed by the shock waves it creates. Some of these EGGs contain enough mass for gravity to win the battle against radiation, causing the gas to collapse and form new stars. Others will be destroyed before they can form stars, their material dispersed back into the nebula. It is a race between creation and destruction playing out over hundreds of thousands of years.

Hubble's Images: 1995 and 2014

The original 1995 Pillars of Creation image was taken with Hubble's Wide Field and Planetary Camera 2 (WFPC2). It combined exposures through filters that isolated specific emission lines: green for hydrogen-alpha, red for singly ionized sulfur, and blue for doubly ionized oxygen. The resulting color palette, while not exactly what your eyes would see, highlights the physical structure of the gas with extraordinary clarity.

In 2014, Hubble revisited the Pillars with its newer, sharper Wide Field Camera 3 (WFC3), producing a higher-resolution image that revealed new details including small jets of material being ejected from newly forming stars embedded within the pillars. A companion near-infrared image peered through the dust to reveal the young stars hidden inside the columns, stars that are invisible in visible light because the dust surrounding them is opaque.

The James Webb Space Telescope also captured the Pillars in mid-infrared light, revealing even more embedded protostars and showing the pillars as semi-transparent structures through which background stars are visible. Each wavelength of observation adds a new layer of understanding to these iconic structures.

Observing the Eagle Nebula Yourself

The Eagle Nebula is a rewarding target for visual observers, though you will not see the Pillars of Creation visually, as they require the resolution and sensitivity of space telescopes or long-exposure imaging. What you will see is the glow of the surrounding nebula and the bright star cluster at its heart.

Finding M16: The Eagle Nebula is located in the summer Milky Way, best visible from June through September in the Northern Hemisphere. It sits in Serpens Cauda, roughly midway between the tail of Scutum's Wild Duck Cluster (M11) and the Omega Nebula (M17). From the Northern Hemisphere, it passes through the southern part of the sky, so a clear southern horizon helps.

Binoculars: Through 7x50 or 10x50 binoculars, M16 appears as a hazy cluster of stars embedded in a faint nebular glow. Under dark skies, you can detect the nebulosity surrounding the cluster, which sets it apart from a plain open cluster.

Small telescope (4-8 inch): A telescope reveals the cluster stars more clearly and, with a narrowband nebula filter such as an OIII or UHC filter, brings out the surrounding nebulosity significantly. You will see the eagle-shaped outline of the nebula that gives it its common name, with the dark intrusion where the Pillars are located appearing as a notch in the bright nebulosity.

Astrophotography: M16 is a spectacular astrophotography target. With a telescope and a cooled camera, you can actually capture the Pillars of Creation from your backyard. Narrowband imaging using hydrogen-alpha and oxygen-III filters produces stunning results even from light-polluted locations, because the filters reject most artificial light while passing the nebula's emissions. Many amateur astrophotographers have produced pillar images that are genuinely breathtaking.

The Pillars in Context

The Eagle Nebula is part of a much larger star-forming complex in the Sagittarius Arm of the Milky Way. Nearby objects include the Omega Nebula (M17), the Star Cloud of Sagittarius, and numerous other HII regions where hydrogen gas is being ionized by young stars. This entire region of the galaxy is one of the most active zones of star formation within our cosmic neighborhood.

Some astronomers have proposed that the Pillars may have already been destroyed by a supernova blast wave that we have not yet observed because the light from that event has not reached us. Spitzer Space Telescope infrared observations revealed a hot dust cloud near the pillars that could be evidence of such an event. If this is correct, the Pillars we see in Hubble's images are a ghost, a portrait of structures that no longer exist, their light still traveling toward us from 7,000 years in the past. Whether this is true remains debated, but it adds yet another layer of wonder to these already extraordinary formations.

For more on the different shapes and structures of nebulae and other deep-sky objects, explore our guide to the types of galaxies that populate the universe beyond our own Milky Way.