Featured Photo by Michael L. Morgan: The Helix Nebula, “Eye of God” (details below)

by Christine Lorraine

A planetary nebula is defined as, “A bright cloud of glowing gas and dust surrounding a highly evolved star,” according to encyclopedia.com. The term “nebula” originated in the mid-1600s, derived from the Greek term “nephele,” which refers to a cloud, fog or haze.

But defining a planetary nebula doesn’t begin to explain how this starry phenomenon came to be identified and understood by astronomers.

Ironically, “planetary nebula” is a term that is directly applicable to stars rather than planets. It was coined by astronomer Sir Frederick William Herschel in the late 1700s, shortly after he discovered the planet Uranus. Legend has it that Herschel dubbed these mysterious and colorful space entities “planetary” because they bore a resemblance to the planet Uranus. He did not realize that a star was at the heart of a planetary nebula until after he had created the term.

Even though Herschel named this illustrious space condition, he was not the first to discover it. That scientific recognition is given to noted French astronomer Charles Messier in 1764.

One of Messier’s most relevant accomplishments was his organized collection of astronomical objects. Messier, while searching for comets, catalogued other space entities that he stumbled upon. These were known as “Messier objects,” and included star clusters, nebulae and galaxies.

Once these observations spread throughout the scientific community, astrologers began to study them and began to understand some of the conditions under which a planetary nebula is formed.

M27 The Dumbbell Nebula in Vulpecula by Michael L. Morgan (details below)

To begin, it’s important to understand that a nebula is disseminated mass, or cloud, of interstellar gas or dust, or a combination of both. Nebulae are usually about 97% hydrogen and 3% helium.

A planetary nebula is comprised of a star, surrounded by a shell of ionized gases emitted by the star; the shell expands and glows. This happens to certain kinds of stars as they approach late stages of their lives. It is also known as an “emission nebula.”

These mysterious space entities have been observed in a variety of shapes, a fact which has yet to be figured out by astronomers. Some are asymmetrical, others are spherical or disk-shaped. At the center of a planetary nebula lies the star. The gaseous cloud surrounding the star continues to expand, moving farther into space, away from the dying star.

After the cloud is gone, the star is considered to be a “white dwarf.”

Because a planetary nebula’s emissions are charged gases, they are among the most breathtaking sights in outer space. In reviewing photos of them, just about every color in the rainbow can be seen.

M57 The Ring Nebula in the constellation Lyra by Michael L. Morgan (details below)

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PLANETARY NEBULAE PHOTO DETAILS from Astrophotographer Michael L. Morgan:

• The Helix Nebula, “Eye of God,” NGC 7293 a planetary nebula in the
  Aquarius. One of the closest planetary nebulae to Earth with an estimated
  distance of about 700 light-years. The central star of the Helix Nebula
  has expanded into a red giant and blown away its outer layers.  A
  similar fate is expected for  our own sun….Taken at Cherry Springs State Park October 8th, 10th and 11th, 2015,
  Celestron C8 @ F7.5 QSI583wsg
  LRGB
  Luminance 24 x 5 minutes binned 2×2
  RGB 15 each@ 4 minutes binned 2×2
  Aquired in Astorart, Stacked in Deep Sky Stacker, aligned in Registar
  and processed in Photoshop

• M27 The Dumbbell Nebula in Vulpecula. Shot the week of August 9th, 2015
  Highland Lakes NJ. Celestron CGE1100, QSI 583wsg, Starizona reducer.
  LRGB L= 18×5 minutes RGB 14 x 2 minutes each, all frames binned 2×2, 172
  minutes total exposure.
• M57 The Ring Nebula in the constellation Lyra. The nebula is a shell of
  ionized gas given off by the central star during the final phases of its
  evolution prior to becoming a white dwarf. It lies approximately 2,300
  light years from Earth. The smudge above and to the right of M57 is
  external galaxy IC 1296.
  Although relatively bright the nebula has an angular size of 1.5 × 1
  arcminutes. The picture represents the full field in my camera with the
  C11 @ F7.5 .

  Started at Cherry Springs State Park the morning of July 17th, 2015. I
  ended up getting clouded over by 2:00 AM and only got about a hours
  worth of data. Completed in Highland Lakes, NJ the morning of July 25th.

Sources

http://www.encyclopedia.com/topic/planetary_nebula.aspx

http://www.thefreedictionary.com/nebula

en.wikipedia.org/wiki/Planetary_nebula

Planetary Nebula Facts to Help on Your Next Project

http://en.wikipedia.org/wiki/William_Herschel

http://en.wikipedia.org/wiki/Charles_Messier

sunshine.chpc.utah.edu/labs/star_life/starlife_proto.html

http://en.wikipedia.org/wiki/Definition_of_planet

http://dictionary.reference.com/browse/nebula

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What is a Planetary Nebula?
By: Christine Lorraine
Originally Published: January 8, 2011 at the now defunct helium.com

THIS STORY AND MY OTHER ORIGINAL WRITINGS FROM HELIUM HAVE BEEN PLAGIARIZED VERBATIM AT:

What is a Planetary Nebula