The Great Orion Nebula

The Great Orion Nebula


The Orion Nebula is a region filled with hot gas and dust, the raw materials for building new stars. It is located in the area of the sword of Orion, the Hunter, a constellation that dominates the northern hemisphere winter sky. The Nebula appears as a fuzzy, star-like area, which is visible without a telescope on clear, dark nights. The Nebula is nearby: it is 1,500 light-years away in our spiral arm of the Milky Way Galaxy.

Nuclear Fusion:

Two or more light nuclei join together to form a heavier

nucleus, releasing energy in the process. This is the most fundamental and basic source of energy in the universe. Two lighter hydrogen nuclei combine to form a heavier helium nucleus. This is a thermo-nuclear reaction involving some mass-loss and resulting in tremendous amounts of energy. The same reaction is being fuelled in the young stars being born in the Orion nebula. Due to gravity, huge chunks of matter is being clustered into proto-stars here.

Protoplanetary Disks/Proplyds:

Disks thought to be made of 99% gas and 1% dust. They appear around young stars, and may evolve into planetary systems like our own. Crucible of Creation Four of the Nebula’s hottest and most massive stars lie near the center. Light from these stars illuminates the Nebula’s “cavern” just as flashlights light up a cave. The cavern contains 700 other young stars at various stages of formation. Some of the infant stars send jets of hot gas into the Nebula at 100,000 miles per hour. These jets appear as thin curved loops, sometimes knotting at the end where they hit denser material. The brightest examples are near the reddish star found in the lower left of the images we have of the nebula.


The four bright central stars are less than a million years old. The Nebula is the same age or younger. The Orion Nebula also contains 153 glowing disks thought to be infant solar systems. Many of the Nebula’s young stars are embedded in the middle of pancake-shaped disks of dust and gas. Astronomers think the disks, called protoplanetary disks or proplyds, may be an early stage of planet formation. Our solar system probably formed out of just such a disk 4.5 billion years ago. 2.5 light years across, covering an area of sky about 5% of the area covered by the full Moon.

Subhajit Ganguly

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