What is the Orion Nebula?
The Orion Nebula is a diffuse nebula about 30 light-years in diameter located in the constellation Orion, beneath Orion’s belt, 1,500 light years from the Earth. A diffuse nebula is so named because it trails off into space, is partially transparent, and lacks any well-defined boundaries. It is one of the brightest and most famous nebula in the night sky, also being one of the best studied. It is also known as M42 as a reference to its Messier number. The Orion Nebula is part of a larger body called the Orion Molecular Cloud Complex, which is present throughout the entire constellation of Orion and contains other famous objects such as Barnard’s Loop, the Horsehead Nebula, M43, M78 and the Flame Nebula. The Orion Nebula itself covers a 10° portion of the sky, about a tenth the size of the Moon’s disc. The Orion Nebula is a stellar nursery, and contains over 700 stars in various stages of formation. Being both an emission and a reflection nebula, it both contains stars that ionize the s
Enormous clouds of dust and gas are found throughout the galaxy. One of the closest is the Orion Nebula, shown in Figure 1.1a, which is 1500 light-years from Earth and measures several light-years across. It is visible to the human eye as a fuzzy patch in the constellation of Orion. The galaxy contains tens of thousands of dark nebulae, so-called because the dust andgas obscure the light of stars behind them. Over time clumps of higher density gas form and grow within some of these, their gravitational attraction drawing matter from the surrounding cloud. As a clump grows, the weight of layer upon layer of gas builds up, increasing the pressure and temperature at the clump’s core. The pressure continues to rise until hydrogen nuclei are packed so tightly together that they fuse, igniting a thermo-nuclear reaction that signals the birth of a star. We see this happening in the Orion Nebula – it is the birthplace of stars. Hot young stars born within the nebula radiate their energy outwar
Enormous clouds of dust and gas are found throughout the galaxy. One of the closest is the Orion Nebula, which is 1500 light-years from Earth and measures several light-years across. It is visible to the human eye as a fuzzy patch in the constellation of Orion. The galaxy contains tens of thousands of dark nebulae, so-called because the dust and gas obscure the light of stars behind them. Over time clumps of higher density gas form and grow within some of these, their gravitational attraction drawing matter from the surrounding cloud. As a clump grows, the weight of layer upon layer of gas builds up, increasing the pressure and temperature at the clump’s core. The pressure continues to rise until hydrogen nuclei are packed so tightly together that they fuse, igniting a thermo-nuclear reaction that signals the birth of a star. We see this happening in the Orion Nebula – it is the birthplace of stars. Hot young stars born within the nebula radiate their energy outward into the surroundin
Over the years of studying this object, astronomers have determined that we are privileged to have a front row view of a stellar nursery. We are literally witnessing the creation of brand new solar systems as we behold this wonder. Some of the stars are estimated to be less than a few hundred thousand years old! In stellar terms, that is barely past the point of having the doctor slapping a newborn on its bottom and getting its first breath of air. The process of star formation begins with a massive cloud of very cold gas and dust. These clouds, known as Giant Molecular Clouds (GMCs), typically contain tens or hundreds of thousands of solar masses of material. The temperature of this material is only a few degrees above absolute zero. Shock waves propagating through the space between stars (typically formed via supernovae explosions) push this material to the point that its own self gravity causes it to collapse and form a substantial number of proto-stellar disks. Each disk forms beca
Can it be seen with the unaided eye? Located in the constellation of Orion, the nebula is one of the closest star-forming regions to the Sun. It contains nearly 300 stars, most of which are seen only in infrared. The nebula can be spotted by the unaided eye just below the belt of Orion. 5. Why do stars eventually move off of the main sequence? They exhaust their supply of hydrogen in their cores and these cores then begin to contract. 6. Why will the Sun become a red giant. What will it be fusing in its core when it is a red giant? After the Sun exhaust its supply of hydrogen in its core it begins to contract. As it contracts the densities and temperture rises. This causes a hydrogen burning shell to develop around the core. The large amount of energy produced by this shell causes the star to expand and become more luminous and cooler. 7. What will be the final structure of the Sun’s core (and other midsized stars) just before it become white dwarfs? The final structure of the Sun will
