Owl Nebula
A planetary nebula with an owl-like appearance in Ursa Major.
The Owl Nebula (cataloged as Messier 97, M97, or NGC 3587) is a planetary nebula located around 2,030 light-years away in the constellation Ursa Major. Its most recognizable feature—a face-like pattern resembling an owl's head—comes from an inner shell that isn't round but instead shaped like a barrel, tilted at a 45-degree angle relative to our line of sight. This nebula is roughly 8,000 years old and formed when material from its central star's stellar wind was expelled as the star moved through the asymptotic giant branch phase.
The nebula's structure consists of three concentric shells, with the outermost shell extending 20–30% farther out than the inner one. It contains about 0.13 solar masses of material, including hydrogen, helium, nitrogen, oxygen, and sulfur, with a density below 100 particles per cubic centimeter. Its outer radius measures roughly 0.91 light-years (0.28 parsecs), and it expands into the surrounding interstellar medium at speeds between 27 and 39 kilometers per second.
At the center lies a 14th-magnitude star that has passed a key turning point in its evolution and is now condensing into a white dwarf. This star has 55–60% of the Sun's mass, shines with 41 to 148 times the Sun's luminosity, and has an effective temperature of 123,000 Kelvin. The Spitzer Space Telescope resolved it as a point source, with no infrared excess that would suggest a surrounding circumstellar disk.
**History** French astronomer Pierre Méchain first spotted the Owl Nebula on February 16, 1781. Méchain, a colleague of Charles Messier, reported it to Messier, who observed it a few weeks later and added it to his catalog as Messier 97 on March 24, 1781. Messier noted: "Nebula in the great Bear, near Beta: It is difficult to see, reports M. Méchain, especially when one illuminates the micrometer wires: its light is faint, without a star. M. Méchain saw it the first time on Feb 16, 1781, & the position is that given by him. Near this nebula he has seen another one, [the position of] which has not yet been determined [Messier 108], and also a third which is near Gamma of the Great Bear [Messier 109]. (diam. 2′)." In 1844, Admiral William H. Smyth classified it as a planetary nebula. When William Parsons, the 3rd Earl of Rosse, observed it in Ireland in 1848, his hand-drawn sketch looked like an owl's head.
- Distance
- approximately 2,030 light years
- Age
- about 8,000 years
- Mass
- 0.13 solar masses
- Outer radius
- 0.91 ly (0.28 pc)
- Expansion velocity
- 27–39 km/s
- Central star mass
- 55–60% of solar mass
- Central star temperature
- 123,000 K
Lore & Background
The Owl Nebula was discovered by French astronomer Pierre Méchain on February 16, 1781. Charles Messier observed it a few weeks later and included it in his catalog on March 24, 1781, noting: 'Nebula in the great Bear, near Beta: It is difficult to see... its light is faint, without a star.' In 1844, Admiral William H. Smyth classified the object as a planetary nebula. When William Parsons, 3rd Earl of Rosse, observed it in 1848, his hand-drawn illustration resembled an owl's head, and it has been known as the Owl Nebula ever since.
The nebula is arranged in three concentric shells, with the outermost shell about 20–30% larger than the inner shell. It holds about 0.13 solar masses of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur, with a density of less than 100 particles per cubic centimeter. Its outer radius is around 0.91 ly and it expands at velocities of 27–39 km/s into the surrounding interstellar medium. The 14th magnitude central star has passed the turning point in its evolution and is condensing to form a white dwarf, with 55–60% of solar mass and an effective temperature of 123,000 K. The star has been resolved by the Spitzer Space Telescope as a point source without infrared excess characteristic of a circumstellar disk. More recent developments include the discovery of a giant red halo of wind extended around its inner shells and the mapping of the nebula's structure.
Reader's Guide
The Owl Nebula holds significance as one of the more recognizable planetary nebulae due to its owl-like appearance, first noted by William Parsons in 1848. Its inclusion in Messier's catalog by Charles Messier on March 24, 1781, following Pierre Méchain's discovery, places it among the historic deep-sky objects. The nebula's structure—three concentric shells with a barrel-like inner shell—provides insight into the late stages of stellar evolution, specifically the asymptotic giant branch phase. The central star, now condensing into a white dwarf, has been studied with the Spitzer Space Telescope, revealing no circumstellar disk. The discovery of a giant red halo and mapping of its structure in the late 1900s have furthered understanding of its expansion into the interstellar medium. For observers, the nebula is located in Ursa Major, near the southwest corner of the Big Dipper's bowl, and can be glimpsed with small telescopes or 20×80 binoculars under good conditions, though its owl-like eye features require a telescope with an aperture of 10 inches or better.
Did You Know?
- Its owl-like appearance comes from an inner shell that forms a barrel-like structure aligned at 45° to the line of sight.
- The central star has an effective temperature of 123,000 K and is condensing to form a white dwarf.
- The nebula expands into the interstellar medium at velocities between 27 and 39 km/s.
Frequently Asked Questions
What is the Owl Nebula?
It's a planetary nebula cataloged as M97 (also listed as NGC 3587) sitting in the constellation Ursa Major, roughly 2,030 light-years from Earth. The nickname comes from a distinctive facial pattern that looks strikingly like an owl's head when viewed through a telescope.
Why does M97 look like an owl's face?
The resemblance comes from an inner shell that has a barrel-like shape rather than a spherical one, and it's tilted about 45 degrees relative to how we're viewing it. That geometry creates the two 'eye' spots and the beak-like appearance fans love to spot.
How old is the Owl Nebula and how did it form?
At roughly 8,000 years old, it's a relatively young planetary nebula that came into being when its central star shed its outer layers during the asymptotic giant branch phase. The star left behind at the center carries about 55–60 percent of the Sun's mass.
How big is the Owl Nebula and how fast is it expanding?
The outer shell stretches to about 0.91 light-years in radius, and the ejected material is moving outward at speeds between 27 and 39 kilometers per second. The total mass of that expelled gas works out to roughly 0.13 solar masses.
Where in the sky can I find the Owl Nebula?
Look toward the constellation Ursa Major, the Big Dipper's neighbor in the northern sky. It's a faint object best observed with a decent-sized telescope, and narrowband filters help bring out the barrel-shaped inner shell that gives it that iconic owl-face look.
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