Starry Night



Starry Night


“Starlight, star bright, please grant me my wish tonight”. This is something I would always say when I was a kid. Sometimes my wish came true, and other times it did not. I always thought stars have magical abilities that grant your wish, or so my mom said, but she only says those things so that I would behave. She told me that a star will always grant your wish if you are a good kid. Well, I fall for it and that is how I ended up where I am right now, otherwise I would be a high school dropout chasing for a dead-end job. Thank you mom for lying to make me a better kid. I love you mom!

Anyways, as I grow older, I found out that stars are not magical; however, they are quite interesting. A star is a massive, luminous sphere of plasma held together by gravity. The closest star to us is our very own sun.  We also see bright stars in the sky all the time, but do you actually know what it is or looks like. And NO, they do not look like the five triangle point-shape extending out, the ones that you often draw. They are actually in spherical shape and the shine is due to the thermonuclear fusion of the hydrogen in its core releasing energy that traverses the star’s interior and then radiates it into space. So that is why we see star shines so bright.



Hydrostaic Equilibrium Equation 



The interior of the star, or rather a stable star, is in a state of hydrostatic equilibrium, in which the forces on any small volume almost exactly counterbalance each other out. The gravitational force is always attractive, implying that an opposing force must exist if a star is to avoid collapsing. Rho is the density and g is the acceleration of gravity at radius r. Also, I am sure that you are aware that some star are brighter than others. Well, this means that the brighter they are, the more likely they live longer. According to stellar energy sources, the rate of energy output of stars, or rather their luminosities, is very large. So the measure of a star lifetime must be related to how long it sustains its power output. Another thing to know about a star is that it has three energy transport mechanisms. The first being radiation, allows the energy produced by nuclear reactions and gravitation to be carried to the surface via photons. The second is convection where transport mechanism in many regions of a star buoyant mass elements carrying excess energy outward while cool elements fall inward. The third is conduction, where transport heat via collisions between particles.

I can ramble on and on about what a star is, but most people say that a picture is worth a thousand words, so here is an image that shows a cross-section of a solar-type star.



Courtesy of NASA



So the next time you look at the stars, enjoy its beauty because magical or not, they are amazing and that they have been with the universe since the beginning of time. To me that is magical enough. Now that you know what a star looks like, quiz your friends and ask them to draw a star. Most people would draw that typical shape that everyone thinks a star looks like, but the amazing thing about my little cousin is that I ask him to draw a star and he draws a spherical shape with a luminosity glow, and he is only 5 years old. WOW.