My Favorite APOD Nebula Images
There are numerous mysteries contained within the Cosmos that have yet to fully be analyzed and appreciated. The unique events that transpire within the Universe everyday are unbelievably remarkable and captivating. Hidden within the immense ocean of stars we see every night lays an even more incredible spectacle in the form of Nebulae. The paragraphs that ensue will delve into the creation of Nebulae, and the many intriguing aspects of the most visually appealing amongst these particular phenomena.
The Astronomy Picture of the Day (APOD) website features many spectacular images of the Universe and the phenomena contained within it. Among this considerable collection of pictures there are several diverse photographs of nebulae; such as, The Great Carina Nebula, The Red Spider Planetary Nebula, The Ring Nebula, The Horsehead Nebula, The Crab Nebula and The Butterfly Nebula. The word, nebula, itself comes from the Greek word for cloud, and is defined as a stellar nursery made of clouds of dust and hydrogen gas.
Furthermore, there are five main types of nebulae; they include emission, reflection, planetary, dark and supernova remnants. Each type appears in a vast array of shapes, sizes and form in different ways. The unique appearance of each nebula depends on temperature, density and how the dust is spatially arranged with respect to the viewer. Although all nebulae are forms of interstellar matter some of them formed from the death of stars while others formed from atoms and simply reflect the light from the nearby stars.
The first nebula, to be highlighted, is The Great Carina Nebula, or NGC 3372, which is found approximately 7,500 light-years away from earth and is easily observed with the unaided eye. “Spanning over 300 light-years this nebula is considered one of our galaxies largest star forming regions. This particular nebula contains young, extremely massive stars; such as, Eta Carinae.” (Nemiroff and Bonnell). The Great Carina Nebula is a bright emission nebula made up mostly of hydrogen and helium gases. The October 15, 2013 APOD image of this nebula appears mostly red because of the hydrogen gas that is excited, by the ultraviolet light, from embedded stars.
Second is the Red Spider Nebula which is also known as NGC 6537, and is categorized as a planetary nebula. Planetary nebulae occur when a normal star, or any class of star, expels its outer gases in the process of becoming a white dwarf star. This particular nebula is positioned about 4,000 light-years away in the constellation Sagittarius, and contains two-lobes. These lobes are produced by heat which is being generated by fast winds, subsequently causing each lobe to expand. “The internal winds within this nebula have been measured in excess of 1000 kilometers per second, from the central stars.” (Nemiroff and Bonnell). During this expansion waves of hot gas and dust collide, thus causing the atoms caught within it to radiate the colorful light...