The Orion Nebula, also known as Messier 42 or M 42, is a bright emission nebula about 1,350 light-years away from Earth and more than 10 light-years across. It’s a nursery of star formation and contains hundreds of O-type young stars. These young stars are clustered about the Trapezium, a nexus of four massive stars arranged in a trapezoidal pattern that shaped the nebula. This gets the hydrogen excited, which causes the nebula to shine brightly. The Orion nebula is vaguely visible to the naked eye and is best viewed through a telescope. It was first discovered by Nicolas-Claude Fabri de Peirescin, a French scholar, in 1610, and in 1880, it was the first nebula to be photographed by Henry Draper in the United States.
In addition to regions of red hue and blue-violet, the nebula has a distinctive greenish tint. The red hue is due to the Hα recombination line radiation at a wavelength of 656.3 nm. The blue-violet coloration is due to the massive O-class stars’ reflected radiation found at the nebula’s core.
The green hue was a question astronomers in the early part of the 20th century couldn’t answer at first, but with a better understanding of atomic physics, it was later resolved that the green spectrum was due to a “forbidden transition,” which is a low-probability electron transition in doubly ionized oxygen.
How to locate the Orion Nebula.
M42 can be seen shining brightly in the Orion constellation. It is the closest star nursery to Earth, so it has a relatively bright apparent magnitude of 4. To find it, you must locate the Orion constellation best seen in the Northern Hemisphere during the winter months and the Southern Hemisphere during the summer months. The Orion constellation has three medium-bright stars in a short, straight row that represent Orion’s Belt.
There would be a curved line of stars “hanging” from the straight row of Orion’s belt if you noticed. These are the stars representing Orion’s Sword. The Orion Nebula can be found about halfway down the Sword of Orion.
It’s easier to see the Orion Nebula the higher the constellation Orion is in the sky. In August and September, the constellation appears in the east just before dawn. From the Northern Hemisphere, Orion appears in the south and highest in the sky around midnight in middle December.
Unlike most nebulae that are difficult, if not impossible, to see with the unaided eye or even binoculars, the Orion Nebula is faintly visible to the unaided eye when viewed on a dark and moonless night. It’s best observed in a dark country sky with a backyard telescope or even binoculars.
Who saw it first?
The first person to identify the Orion Nebula through a telescope is French astronomer Nicholas Peiresc from 1580 to 1637 and made notes during 1610. Most of the credit for the discovery of the nebula is given to Christiaan Huygens. A Dutch astronomer and an avid observer that built and used several long-focal-length refracting telescopes. The Orion Nebula’s first drawing was published in 1659 in Huygen’s book titled the Systema Saturnium.
Charles Messier, a French comet hunter, was the one who really made the Orion Nebula well known. Messier 42, the Orion Nebula (M42) was added in Messier’s famously known catalog of deep-sky objects. The nebula was one of those that piqued the interest of the public.
In astronomy, the Orion constellation is one of the most important constellations because one of the nearest and most active stellar nurseries in the Milky Way resides there. In these stellar nurseries, tens of thousands of new stars have formed within a brief period (within the past 10 million years) in astronomical terms. If we compare it with our own Sun, which is now 4,600 million years old, when scaled into a human time, the formation of new stars in Orion would have gone on for just a month compared to 40 years of the Sun’s formation.
The Orion Nebula is not just one of the most photographed objects in the night sky; it is also the most scrutinized and most intensely studied celestial object. Through studying the nebula, it was revealed that the stars and planetary systems are formed from the clouds of gas and dust collapsing. Astronomers have directly observed the nebula’s photo-ionizing effects of massive nearby stars, intense and turbulent motions of the gas, protoplanetary disks, and the brown dwarfs.
The Orion Nebula plays a big role in astrophysics in that it can be said that our understanding of star formation is based mainly on what we’ve studied in the Orion Nebula. In fact, it is no surprise that the nebula, located at 1500 light-years, is one of the most studied objects in the night sky.