Podcaster:  Pamela Quevillon

Title: The Big Explosion No One Saw

Organization: Speak Easy Narration

Link :  http://speakeasynarration.com ; http://www.unawe.org/kids/unawe1348/

Description: Space scoop, news for children. There’s no atmosphere in space. This means that there is no weather; no cool breeze, no torrential rainfall and definitely no snow…but there are clouds.

Feature image credit: Chandra X-Ray Observatory

Bio: Pamela Quevillon is a voice actress who most often lends her voice to science and science fiction content. You can find her work on the “Escape Pod” and “365 Days of Astronomy”, as well as on her site

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2013, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.

Transcript:

This episode is a story of

The Big Explosion No One Saw

Supernova. Credit: Chandra X-Ray Observatory

About once or twice every 100 years, a gigantic nuclear bomb detonates in our Galaxy. In just a few short weeks, it blasts out as much energy as our Sun will in its entire lifetime! This powerful explosion is called a ‘supernova’, and it is the result of a star dramatically ending its life.

The most recent supernova in our galaxy, the Milky Way, happened just over 100 years ago. But, unfortunately for our great-great-great grandparents, the explosion was hidden behind thick clouds of gas and cosmic dust, far away from the Earth. So they couldn’t witnessed this very rare sight. Because of this cosmic dust, it wasn’t until 2008 that a group of astronomers finally stumbled upon the remains of the obliterated star, which you can see in the photograph used for this podcasts album art.

Normally, when a supernova like this happens, the star’s material is blown out evenly in all directions. This leaves behind a cloud that is more or less neat and symmetrical, but the object in this picture doesn’t follow a neat pattern. Most of the star’s material was blasted towards the top of the image, and it’s still traveling in that direction extremely fast. From these clues, astronomers have deduced that this must have been an unusually energetic and messy supernova explosion!

As far as we know, the last supernova in the Milky Way was over 100 years ago. If they happen on average every 100 years or so, another one should be due really soon. Keep your eyes on the skies and you might be the one to spot it first!

Cool Fact: There was a famous supernova at the end of the twentieth century called SN1987a. This explosion happened in a nearby galaxy and was so powerful that it was visible for four whole months!

Supernova are very important for life here on Earth. Heavy atoms like the iron in your blood, and rare earth metals that are in your phone and other electronics are formed in the massive stars that die as supernovae.

Over the course of their life, these stars – which are 8 times the size of the Sun or larger! – go through many different stages. They start like any normal star, and consume Hydrogen, which they burn into Helium. When all the Hydrogen in their core is eaten up, the start consuming even heavier atoms! First Helium, then on up through the Periodic Table, from Carbon, Nitrogen and Oxygen, to eventually even burning Silicon into Iron!

Once Iron is created, nuclear burning in the star stops. Iron is the heaviest atom that can be fused together in processes that still give off energy. Everything heavier, atoms like gold and silver, requires that energy get added. When the star has an iron core and the nuclear reactions stop, things turn bad very quickly. As long as the star has nuclear reactions, it is generating huge amounts of light that can actually push outward, holding up the outer layers of the star. When the pressure from the light goes away, those layers collapse violently, and get so hot and so dense that a new, explosive round of nuclear reactions takes place. Its this explosive bounce that drives the supernova explosions we observe.

Its during these explosions that all the atoms heaver than Iron are created. All precious metals are made. When you buy jewelry – you are buying a piece of a supernovae. And you … you are made of star dust.

End of podcast:

365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. In the new year the 365 Days of Astronomy project will be something different than before….Until then…goodbye.