A supernova is a profound stellar experience that occurs about once every 50 years, and NASA’s evolution of technology has allowed us to understand them better than ever before. While they do not happen frequently, you are more than likely to experience one in your lifetime.
Although supernovas have a profound impact, they are widely misunderstood by the general public.
The 101 on Supernovas
A supernova is the largest explosion that can occur in the universe. It is the result of a giant star exploding, as the natural end of its lifecycle. Giant stars can live for millions of years, but they do not live forever. When it’s their time, so to speak, they go out with a bang, quite literally, by creating a supernova.
A star contains nuclear energy within its core, which means that the interior of a star is incomprehensibly hot. Over time, this causes pressure to build up within the core, while the force of gravity is forcing the star to remain as compact as possible. This causes two conflicting sources of pressure that keep the star homeostatic.
A supernova occurs when the nuclear energy eventually runs out, as each star contains a finite amount. This causes the core of the star to cool, and so the pressure of gravity can now successfully cause the star to collapse. The collapse causes an enormous shockwave that results in an explosion, which occurs within seconds. This is the supernova, and it’s nothing short of spectacular in terms of its scale.
What is left behind after a supernova is a nebula, which is a cloud of gas that expands over time. If this nebula is large enough, it turns into a black hole, but this only occurs if the star was particularly gigantic, several times the size of the sun. This is why black holes are so rare – stars this size are incredibly rare in the universe.
We talked about supernovas that are a natural part of the life cycle of a giant star, but there’s another type of supernova that can occur, rather abruptly and unpredictably. It occurs when two stars orbit each other, with at least one of them being a white dwarf, which is a star the size of Earth or larger, which has run out of nuclear energy. Due to gravitational pull, one star can absorb matter from the other, which can cause a supernova to occur. A supernova can also occur when these two orbiting stars collide with one another.
A supernova can be so bright that it blinds us to the rest of a galaxy for up to months at a time. But, seeing them isn’t so simple. Space is filled with dust and being able to see a supernova from far away can be a challenge. NASA does employ their Nuclear Spectroscopic Telescope Array (NuSTAR) to observe supernovas using X-ray technology, which can also predict a supernova that is about to occur.
Are Supernovas Dangerous to Earth?
Supernovas are profound events that have an enormous impact on the space around them. But they are not known to be threatening to Earth. They simply do not take place close enough to our planet to create a negative impact. Theoretically, if one were to occur awfully close to us, it could cause mass extinction. There are also no threats of supernovas that can harm our planet in the foreseeable future, and NASA has gotten better and better at predicting them long before they occur by examining the conditions of giant stars in our solar system.
It is worth pointing out that there has never been a supernova that impacted Earth. But new evidence shows that there was one that did come close in the last nearly 5 billion years. This event took place 2.5 million years ago, and the evidence is the sample of 60Fe, an iron isotope that is released when supernovas take place.
What a Supernova Sounds Like
No one has ever heard a supernova with their ears because these events take place too far away. If you were able to hear a supernova at its full decibel level, it would mean that you were adjacent to the star when it exploded, and this clearly would not be a survivable incident. So, how loud are supernovas?
According to researchers, a supernova is about 194 decibels. It’s measured by the force of the pressure that it creates, which produces shockwaves. For comparison, anything above 100 decibels could damage human ears.
Therefore, it is safe to say that your sense of hearing would not survive the sound of a supernova. And no, the sound of a supernova cannot be heard from Earth.
When is the Next Supernova?
Up until recently, it was predicted that there would be a supernova event in 2022, in the Cygnus constellation. But, since then, this prediction has been redacted, as the event now seems to not create an explosion. KIC 9832227 is the star in question, and it will eventually explode, but not in the next few years.
Overall, a supernova is a phenomenal space event that occurs rarely but has major implications when it does occur. While they are not considered threatening to our home planet, they are huge explosions that are both massively bright and loud. Thanks to NASA technology, we can observe and predict them better than ever before.