TEACHER SCIENCE CONTENT/ RESOURCE CURRICULUM LINK EARTH SYSTEMS / ASTRONOMICAL SYSTEMS / STARS STARDOME OBSERVATORY & PLANETARIUM FACTS, RESOURCES AND ACTIVITIESf ou ON...r Sun The death o Planetary nebula come in a huge variety of colour and symmetry. Credit: NASA (Planetary Nebula) As with all stars in the Universe, our Sun will not last forever. Most people are familiar with what happens to large stars when they die. Supernova explosions send out vast clouds of gas and dust, leaving behind neutron stars or even black holes. These violent explosions are some of the most powerful events known to us but not all stars will meet such a fiery end. Our Sun is one of them. It is not massive enough to explode in a supernova. Instead, it will slowly puff out the remaining matter back into space in what is known as a planetary nebula. These beautifully colourful, often circular, objects litter our galaxy, leaving behind white dwarf stars. When our Sun runs out of core hydrogen in about 5 billion years, nuclear fusion will stop because the temperature is insufficient to fuse helium into heavier elements. Gravity then gets the upper hand, compressing the core and raising the Hubble snaps a temperature. As the temperature rises a shell of beautiful show of the hydrogen surrounding the core will undergo fusion Helix planetary nebula. causing the overlying stellar envelope to expand Credit: NASA outwards. As the Sun’s surface area increases, it will cool to become a red giant for the next billion years. As They are also a the core continues to contract, temperatures reminder of the can reach 100 million K, and the fusion of amazing recycling helium into carbon and oxygen begins. Planetary nebulae process of stars. Once the core helium is consumed, have nothing to do with The remaining the core contracts again and a shell planets at all. They are heavy elements of helium will start burning beneath named so because their that are thrown the hydrogen-burning shell. The circular shape made early back into space will outer layers of our Sun will become astronomers describe eventually coalesce them as ‘circular, unstable and thrown off back into under gravity to form new nebulae, and eventually stars, fading planets’ in space, becoming a planetary nebula. to begin the whole process again. It’s an amazing reminder the night sky. All that will remain in the core is a that the heavy metals and elements that we use on Earth white dwarf. were forged in the cores of dying stars eons ago. Planetary nebulae are the result of the deaths In the famous words of astronomer Carl Sagan; of smaller stars with masses between 1-8 of our own “The nitrogen in our DNA, the calcium in our teeth, Sun. Any larger and they will explode in more violent the iron in our blood, were made in the interiors of events. The beautiful colours of planetary nebulae collapsing stars. We are made of star stuff”. are caused by the ionization of atoms in the cloud of elements left over. The different colours indicate different elements, like hydrogen and oxygen. Check out these other resources... Planetary nebula gallery: nasa.gov/mission_pages/chandra/multimedia/planetary_nebula.html For a more advanced resource on the topic, check out our other resource: stardome.org.nz/wp- content/uploads/2019/06/Stardome-Education-Worksheet_Stars-Part-Three.pdf

What happens to the elements that are thrown into space? How long will our Sun live? Why don’t smaller stars DISCUSSION STARDOME.ORG.NZ explode in a supernovae? POINTS 09 624 1246 ACTIVITY

STARDOME OBSERVATORY & PLANETARIUM

WHAT'S GOING ON? ula Milk is mostly water but it also contains ilky neb vitamins, minerals, proteins and tiny M droplets of fat. Like other oils, milk fat is Make your own colourful planetary nebula! a non-polar molecule, meaning it doesn’t dissolve in water. When soap is mixed YOU 'LL NEED in, the non-polar (hydrophobic) portion A flat tray or plate of micelles (molecular soap structures in solution) break up and collect the Milk (full cream is best) non-polar fat molecules. Then, the polar Dishwashing liquid surface of the micelle (hydrophilic) Cotton bud (or sponge) connects to a polar water molecule with Food colouring of your choice. the fat held inside the soap micelle. Thanks to the soap connection, the WHAT TO DO non-polar fat can then be carried by the polar water. 1 Take the flat dish or plate and pour in enough milk so the bottom is covered. The molecules of fat move in all directions as the soap molecules race 2 Take your food colouring and place 1-2 drops in the centre around to join up with the fat molecules. of your milk dish. You can drop different colours on top of each other to create more colourful nebulae but be careful The added food colouring allows us to not to mix them with them milk too much. watch this reaction happen that would otherwise be invisible. This is why you 3 Take your cotton bud (or sponge) and soak this in your dishwashing liquid. can expect milk with a higher fat content to produce larger explosions of colour! 4 Take the cotton bud, and place this in the centre of your food colouring drop and hold it there. We know this isn’t exactly a planetary 5 You will see an explosion of colour as the food colouring nebula but these chemical processes expands out and away from the centre, creating a beautiful nicely replicate the beautiful colour and planetary nebula! vibrance of one!

Credit: Shocking Science

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