A Star is Born

Today I was thinking about stars.  Because…well, doesn’t everybody?  So I did a little reading to brush up on my knowledge of the life cycle of the star.  Since we see so many stars in the sky, we may think of them as commonplace.  But some pretty extraordinary stuff happens during a star’s lifetime.  

Baby Stars

A star is born when a large cloud (light years across) collapses under its own gravity.  Very cold temperatures soon warm up as atoms “fall” toward the center, growing closer together and rubbing against each other.  Some of the generated heat remains trapped inside.  The temperature and pressure ignite nuclear reactions.

Active Stars

The nuclear reactions produce fusion.  The star works at turning hydrogen into helium.  It produces energy.  All the heat and light we receive from the sun come from these fusion reactions.

Dying Stars

Eventually a star runs out of hydrogen to burn.  When this happens, a variety of deaths await the star – depending on its size.  Smaller stars “burn out,” cool down, shed outer layers (such as the red giant shedding a new nebula seen below.)  Larger stars end in supernovae explosions, sometimes forming black holes.

 

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The Sun’s paintbrush

It’s on my life bucket list to see the Aurora Borealis or Aurora Australis.  This week, a CME (Coronal Mass Ejection) hit Earth’s magnetic field, causing a beautiful light show as far south as Lithuania.  What makes the lights colorful?  Basically, solar wind from the sun collides with the Earth’s magnetic field.  The magnetic field is weaker in the poles and high latitudes, so some of the Sun’s charged particles get in and stir up excitement.  The excited gas molecules in our atmosphere emit light:  Low altitude oxygen emits green, high altitude oxygen emits red, low altitude nitrogen emits blue, and high altitude nitrogen emits purple.

Here are some pictures of this week’s light show, including one from astronaut Reid Wiseman on the International Space Station!  Check out this site for aurora forecasts: http://www.aurora-service.eu/aurora-forecast/

 

Lights in Vabalninkas, Lithuania, Credit: Tadas Janušonis and spaceweather.com

Lights in Vabalninkas, Lithuania, Credit: Tadas Janušonis and spaceweather.com

 

Aurora Borealis from the International Space Station, Credit: https://twitter.com/astro_reid/status/501867289910992897/photo/1

Aurora Borealis from the International Space Station, Credit: https://twitter.com/astro_reid/status/501867289910992897/photo/1

Aurora forecast August 21, 2014, Credit: http://www.aurora-service.eu/aurora-forecast/

Aurora forecast August 21, 2014, Credit: http://www.aurora-service.eu/aurora-forecast/

Lights in Kuusalu,Harjumaa,Estonia, Credit: Jüri Voit and spaceweathergallery.com

Lights in Kuusalu,Harjumaa,Estonia, Credit: Jüri Voit and spaceweathergallery.com