What Is A Nebula?

See that giant cloud of dust and gas that is spread across the night sky? That is a nebula. The world nebula comes from the Spanish word for “cloud”. For many years, these massive formations have intrigued scientists by providing them with light years of exploration.

Nebulae come from dying stars, such as supernovas, that explode, releasing gas and dust. There are other nebulae out there that are known as “star nurseries”, as these are the regions where brand new stars are coming into formation.

Nebulae are made up of mostly helium and hydrogen. The dust and gas spreads out across millions and millions of miles, though as gravity begins to pull the matter together, the clumps become much larger and stronger. These dust and gas clumps will eventually become so large that it will collapse on itself, forming its own field of gravity. This massive collapse helps to heat up the core of the nebula, which eventually turns into a star. 

Currently, there are four major classes of Nebulae:

  • Diffuse Nebulae – These do not have defined boundaries. They are divided into two sub-groups: Emission Nebulae and Reflection Nebulae. Emission Nebulae are known as HII regions, as they are made mostly of ionized hydrogen. Reflection Nebulae are known to release incredible amounts of light, which reflects off the stars nearby.
  • Dark Nebulae – These are opaque clouds without radiation that is visible. Thanks to the large amount of dust, these are excellent infrared emissions sources.
  • Supernova Remnant Nebulae – These are formed after supernova explosions. These explosions leave behind a cloud of gas and dust to create the Nebula formation.
  • Planetary Nebulae – These are formed at the end stages (Red Giant Phase) of dying stars. The stars lose enough material that the emitted UV radiation ionizes any of the surrounding dust material.

How Were Nebulae Discovered?

During the Middle Ages, many astronomers noted the presence of nebulous objects throughout the night sky. In 150 CE, Ptolemy wrote about the nebulous Almagest stars in his book. Here he discussed the luminous regions that appeared between Leo and Ursa Major. In 964 CE, Abd-al-Rahman al-Sufi, a Persian Astronomer of the time, noted a small cloud in the Andromeda Galaxy. 

As telescopes improved over time, the first nebula observations were made. In 1610, Nicolas-Claude Fabri de Peiresc, a French astronomer of the time, recorded the very first observation of a nebula known as the Orion Nebula. It wasn’t up until 1659 that the first study of the Orion Nebula was performed by Dutch physicist Christiaan Huygens.

Largest Nebula Known To Man

The largest Nebula in the universe is known as the Tarantula Nebula. This massive star factory is about 1000 light-years in length. It was first discovered by Nicolas-Louis de Lacaille during a Cape of Good exploration. It is extremely luminous with an estimated mass cluster of around 400,000 solar masses. Scientists believe that it will eventually become a globular cluster.

This particular nebula is the most active of the starburst regions in the local galaxy group. Before it was classified as a Nebula in 1751, it was thought to be a massive Magellanic Cloud.

Nebula Fun Facts

Contrary to what you might think from looking at photographs, Nebulae are constantly in motion. The nebulous clouds mix and churn all the time, creating magnetic fields.

As you now know, stars are formed within Nebulae. According to astronomers, the gas and dust that are present within nebulae will compress together with the power of their own gravitational force. As the clouds contract and compress, the entirety of a nebula becomes much denser. As the nebula becomes more dense, it also becomes much hotter. When the nebula reaches maximum heat, the hydrogen inside will ignite, creating new stars.

Planetary Nebulae have what we know as “bipolar structures”. Essentially, the look like hourglasses with almost symmetrical triangles spreading out in each direction from the center. Many people say that they look just like butterflies. 

There is a nebula out there called the Horsehead Nebula, which you guessed it, resembles the head of a horse. It is a dark nebula that is incredibly fascinating. It took form thanks to the light that surrounded it. The dark clouds that form around it helps to create the shape, similar to how a shadow is created.

How Far Is The Nearest Nebula?

The Helix Nebula is the closest planetary nebula to Earth and can be found in the constellation Aquarius. It was discovered in the early 19th century by a man named Karl Ludwig Harding. The distance is around 694.7 light years from Earth. Many refer to this Nebula as the “Eye of Sauron”, referencing a pop culture entity from Lord of the Rings.

Latest Nebula News

In recent news, the Crab Nebula has just hit Earth with some of the highest-recorded astrophysical gamma rays of all time. Astronomers detected this blast from a unique observatory in the Tibet mountains. It is known as the Tibet Air Shower Array, as it is composed of an array of underground pools that can detect cosmic particles with high energy. The nebula hit Earth with over 100 trillion electronvolts. To put that into perspective, a mosquito has about 1 electronvolt of energy. The Hubble Telescope has just recently captured a firework-like explosion of a cosmic nebula eruption that has been happening for almost 200 years. This petulant nebula known as Eta Carinae, is now exploding with red, white, and blue gases in a somewhat dramatic and patriotic display. This ‘great eruption’ first began in the 1840s.