The Pencil Nebula

Looking more like the doodles on a celestial notepad, how did this strange nebula form?

Nebulas come in all shapes and sizes, often appearing as a tenuous cloud of gas. However, 815 lightyears away in the constellation Vela sits a nebula often said to resemble a witch’s broom. However, magical as it may appear, this nebula was born in the same way as any other.

When a star grows to a point where it has reached its nuclear fusion limit, it fights a losing battle with gravity as gravitational forces struggle to balance the outward pressure generated by nuclear fusion. Eventually, the star’s core collapses and violently explodes in a supernova.

Around 11,000 years ago, anybody on Earth who happened to be gazing toward Vela would have been able to spot the star that created the Pencil Nebula. All of a sudden, the star became 250-times brighter than Venus in the night sky; for a time it would have even been visible in the day.

As a star goes supernova it ejects gaseous debris known as the supernova remnant, which produces an expanding gas cloud. This debris is dispersed into the interstellar medium at supersonic speed, where it then collects and forms this new cosmic real estate. At the final boom of a supernova explosion shock waves pulsate through space, sweeping through the gaseous material already emitted.

The Pencil Nebula was part of a shock wave travelling at millions of kilometres per hour that was sent crashing into dense gas regions, causing it to form its iconic filaments and ribbon-like appearance.

The energy from the shock wave would have heated the dense gases to millions of degrees Celsius, and after they cooled down the nebula began to glow, making it easier for telescopes such as the Hubble to spot it.