How big is Eagle Nebula? | Scale of the Universe

The Eagle Nebula is a cloud of gas and dust where new stars are forming, about 5,500 light-years from Earth in the constellation Serpens. A light-year is the distance light travels in one year, about 9.46 trillion kilometers. The bright part of the nebula is about 56 light-years, or 530 trillion kilometers, across at its widest. At its heart are the Pillars of Creation, towering columns of dust and gas.

Size

A nebula has no sharp edge, so its size depends on how faint a glow is counted. The New General Catalogue of nebulae and star clusters gives the Eagle Nebula and its star cluster a longest dimension of 35 arcminutes. An arcminute is one-sixtieth of a degree, so that is a little more than half a degree of sky.

Turning an angle on the sky into a width needs the distance. The Gaia space telescope has measured the distances of hundreds of stars in the nebula's star cluster, placing the cluster about 5,500 light-years away. At that distance, 35 arcminutes is about 56 light-years.

NASA gives the nebula's size as 70 by 55 light-years and its distance as 7,000 light-years. At the closer Gaia distance, the nebula works out about one-fifth smaller. Fainter glowing gas spreads farther: a 1959 catalog of glowing hydrogen clouds gives the whole region a width of 90 arcminutes, or about 145 light-years.

Size comparisons

Seen from Earth, the bright part of the nebula is about as wide as the full Moon.
The Pillars of Creation are about 4 to 5 light-years tall, so the nebula is about 11 to 14 times as wide as the pillars are tall.
If the pillars were shrunk to the height of a person 1.7 meters (5 feet 7 inches) tall, the nebula would be about 19 to 24 meters (63 to 79 feet) wide.
The Orion Nebula, a cloud where stars are forming about 1,350 light-years from Earth, is about 24 light-years across, a little less than half the width of the Eagle Nebula.
The nebula is about 13 times as wide as the distance from the Sun to Proxima Centauri, the nearest star.

The Pillars of Creation

The Pillars of Creation appear in some of the Hubble Space Telescope's best-known images. New stars are forming inside them, hidden by dust in visible light. Hubble's infrared images see through the dust and show the young stars.

Ultraviolet light from a cluster of young stars shines on the pillars, and winds from those stars are slowly wearing them away. Another column of cold gas and dust in the nebula, a spire 9.5 light-years long, is more than twice as long as the distance from the Sun to its nearest star.

One name for two objects

The Eagle Nebula is also called Messier 16, or M16. That name covers two objects that catalogs list separately. One is the glowing cloud, cataloged as IC 4703. The other is the star cluster inside it, NGC 6611.

The Swiss astronomer Jean-Philippe Loys de Chéseaux discovered the nebula in 1745. The star cluster can be seen through a small telescope, but seeing the Pillars of Creation takes a large telescope and a clear, dark sky.