Helix Nebula: The Eye of God
Few discoveries in space have captured our imaginations, like the Helix Nebula. The Eye of God, named such because it looks like a gigantic eye, is instantly recognizable across cultures, languages, and geographic borders.
Planetary scientists have a keen interest in learning about the Helix Nebula. The same star evolutionary process is underway with our star that took place thousands of years ago at the location of the Helix Nebula.
What is a Nebula?
A nebula is an enormous cloud of hydrogen (90%), helium (9%), and trace elements of carbons, nitrogen, and magnesium (1%). Add a bit of dust and plasma to the mix, and you have a Nebula. Nebula is a Latin word meaning “cloud or mist.”
Five Different types of Nebulas
There are five different types of Nebulas. Emission, Reflection, Dark/Absorption, Planetary, and Supernova remnants.
- Emission
Emission Nebulas emit visible light, resulting in the gasses inside the Nebula glow. Stars that are nearby or within the Nebula energize the Nebula’s gas. Ultra Violet (UV) radiation overwhelms the hydrogen and helium gasses with energy, and electrons are stripped from the hydrogen atoms. The stripped electrons recombine with the hydrogen atom and shed energy. The shed energy is visible light.
The Orio Nebula was recently photographed by the James Webb Space Telescope.
- Reflection
Light from nearby stars is reflected and scattered throughout Reflection Nebulas. The reflected light is bluish after scattering reflected light from fine dust particles to fine dust particles. Reflection Nebulas are often the home of star formation.
- Dark/Absorbtion
Containing a large amount of dust, Dark or Absorption Nebulas don’t reflect or create visible light.
- Planetary
A planetary Nebula is created when low, and medium-mass stars expel their outer layers of gas after the star has used all of the hydrogens in their core. When the core is depleted of all hydrogen, it expands into a red giant. The expansion leaves a hot core that ejects the gasses “out.” The expanding gas forms many different shapes as they develop.
- Supernova Remnants
There’s a reason Supernova is a common term. A large sun can explode with the brightness of ten billion suns. Supernova remnants are the remains of the sun after the explosion.
The ejected material is projected into space at approximately 90 million miles per hour (144.8 million kilometers per hour.) Ejected material and previous shed elements collide, heat up, and emit x-rays. A neutron star is created at the core of the previous star and sheds visible light, radio waves, and x-rays.
The Crab Nebula, pictured above, was first detected in 1054 by Chinese astronomers. The exposure was so bright it was seen in the sky during the day. The ejected material is still expanding away from the star at a rate of 3 million miles per hour (4.8 million kilometers per hour.)
Helix Nebula Spotting
If you gaze up into the night skies at the right time of the year (early spring in the southern hemisphere), you’ll be able to see the Helix Nebula with a pair of binoculars. The ease of detecting the Nebula and its unusual shape of an eye has captured humankind’s interest for hundreds of years.
The sheer size of the Nebula may make it difficult to detect for amateur astronomers. In the night sky, the Nebula is approximately half the size of the moon. That’s quite large for a telescope to capture an image in a single field of view. The structures of the Nebula may be too faint for “good” telescope focusing.
A cheap telescope with a wide field of view may suit you better than more expensive gear. It is possible to detect the Nebula with the naked eye in a dark environment with minimal light pollution.
Nebula type
The Helix Nebula is a planetary nebula. It was formed late in the lifespan of a star (that was there before it) as the outer layer of stars gases is ejected into space.
How was it named?
This Nebula has many names; Helix Nebula, NGC 7293, Caldwell 63, God’s Eye Nebula, Eye of the God, or The Eye of God. Located just 650 light years away from earth, it’s practically our next-door neighbor.
- Fun fact! With current technology, it takes humans approximately 4,000 years to travel one light year. Reaching the Helix Nebula would take about 2.6 million years. Better pack a lunch.
Name History:
Helix Nebula-
Visually appears similar to a coil of springs that’s helix in nature when viewed from the top down.
Insider hint: Don’t confuse the Helix Nebula with the Double Helix Nebula. The Double Helix Nebula is an Emission Nebula located in the Sagittarius Constellation.
Eye of God-
Visually appears quite similar to a gigantic eye. The name captured the public’s interest after the Hubble telescope published crystal-clear images in the early 2000s.
Caldwell 63
The Caldwell catalog is an astronomical list of galaxies, star clusters, and Nebula. Amateur astronomers compile it for use in celestial observation. Unlike other records, the Caldwell listing utilizes the declination of the object in the sky, not the order in which it was initially detected or observed.
Shape
The Helix Nebula is cigar-shaped. Our earth view of the Nebula is from one end of the cigar. Imagine holding the cigar in your mouth before you light it. Lift the cigar to eye level and move it to the center of your left eye. That’s our view of the Nebula from the earth.
Dimensions
Scientists estimate that the Helix Nebula is one million trillion miles long and
- Length: 3.3 light-years (13,200 years for humans to travel from one end of the Nebula to the other end of the Nebula.)
- Radius: 2.87 light-years (11,480 years for humans to travel from the edge to the center of the Nebula.)
- Diameter: 5.74 light-years (22,960 years for humans to travel across the Nebula)
Birth
Star GJ 9785 shed its outer layers of helium and hydrogen approximately 10,600 years ago. The shedding of GJ 9785’s out layers gave birth to the Helix Nebula. Calculating the expansion rate of the gases allows scientists to estimate (in essence, rewind time) when the expansion began. Those calculations provide an age range of approximately 9,000 to 13,000 years ago.
Wrap up
The Helix Nebula is a planetary nebula. Humans have been able to image the Helix Nebula with telescopes for several hundred years. The Hubble Space Telescope brought the Nebula into sharp focus in the early 2000s when NASA/ESA began releasing high-resolution images.
Scientists are learning about the final phase of the evolution of a star, the death phase. The Helix Nebula is a window into earth’s future in three billion years when our sun runs out of fuel.