A nebula, translated from Latin as mist or cloud, may be one of the most fascinating celestial phenomena. And, as you might have guessed, such an old name usually means that you do not need advanced optics to enjoy its view in the sky – and you’d be almost right! Some nebulae can, indeed, be seen without advanced telescopes, but due to their misty nature, this could prove trickier than anticipated. Besides, a few other technicalities make the naked-eye view not as breathtaking as one might hope – but before we get to those, let’s start with some basics – what is nebula, why it’s called this way, and what is it made of?
Nebula’s Meaning & Composition Explained
A nebula is a cosmic cloud composed of ionised gases and stellar dust. The exact nebula size and composition may differ, but all are essentially huge gaseous clouds that look like misty spots in the night sky. Depending on their exact composition and formation logic, nebulae can take on very peculiar shades – but the trick is, our eye can only see a fraction of the available light spectrum – usually in red and green wavelengths. Without filters on our telescopes, most nebulae would indeed look like a fog – often, a greyish one. But definitely not all of them because the term nebula encompasses a wide range of cosmic clouds that vary by type and exact composition – so let’s take a better look at those!
How are Nebulae Formed?
Most nebulae emerge in star-forming regions when interstellar gases and dust collapse under gravity, eventually forming a star. So, is a star born in a nebula? Yes, but not in every nebula – some misty clouds emerge after a supernova star explodes, emitting its gaseous outer layers into space. Sometimes, when the star dies and sheds its outer layers, the core remains intact – and these clouds are especially impressive to behold because the remnants of a core illuminate the surrounding gas.
So, the misty cloud could act both as the star’s nursery or its grave – depending on the circumstances. It is also believed that some nebulae might have emerged as a result of collisions between galaxies or other high-energy phenomena that could trigger the compression of gas.
Types of Nebula Explained
According to space news resource Orbital Today, the classification of nebulae is a relatively new issue that has not been raised much in the past. Traditionally, any misty area in the open cosmos was referred to as a nebula – despite all the differences in their formation logic and composition.
Still, as our telescopes, along with our understanding of the phenomena, advanced, it became clear that a more specific distinction could be necessary. Based on the nebula facts we have now, the clouds are subdivided into:
- Emissive, with a shining star core inside, which emits the light we see. They shine most brightly and have the longest research history because the bright light makes them easy to spot.
- Reflective nebulae do not have their own shiny core that emits light, but they are still visible because they reflect light from nearby stars.
- Dark nebulae block light from other stars instead of emitting or reflecting it. From our perspective, they are seen as dark dots without any light, so for a long time, this phenomenon was not even associated with nebulae.
- Planetary nebulae is a rather old name dating back to a time when we did not have advanced enough optics to discern the dying star core in the cloud. The term was coined by William Herschel because planetary nebulae are spherical in shape and resemble the gas giants in our solar system when viewed through a telescope. Yet, they have nothing to do with planets and are essentially emissive clouds, but so far, the term persists.
Another common nebula location is around the supernova remains – as already explained, when a star explodes and sheds its gaseous layers, a huge cloud is formed. Usually, clouds around the supernova remain to have peculiar, striking shapes, i.e., the Crab Nebula with its extending, shining arms. But which other ‘famous’ nebulae can we see without complex equipment?
Nebulae Visible to the Naked Eye
Under the right conditions, some stellar ‘mists’ can be seen with the naked eye, especially in places with minimal light pollution. Here are some shining examples:
- Orion cloud, best visible in the Northern Hemisphere in winter;
- Lagoon, which usually appears in the Northern Hemisphere in summer;
- Tarantula nebula appears in the Southern Hemisphere in late summer and is visible through most of the autumn.
Of course, catching sight of those amazing phenomena will also depend on the time of the year, the viewer’s location, and atmospheric conditions. If you would like to see the nebula with the naked eye, we suggest you download a star-gazing app (most come with free versions) to make your first astronomy steps a bit easier. And don’t forget to dress warm!
Author: Emma Thorpe
