I Felt That

Today's Moon Phase!

Keep track of the Moon on MoonGiant as it does it's monthly dance around the Earth

Full Moon day!!!

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THE LIFE OF A STAR: CLASSIFICATION

In order to understand the life of a star, we must understand star classification.

        And there are SO many different ways to classify a star.

        In star classification, understanding the relationship between color and temperature is crucial. The greater the temperature of the star, the bluer they are (at their hottest, around 50,000 degrees Celcius), while red stars are cooler (at their coolest, around 3,000 degrees Celcius). This occurs on a wide range (fun fact: stars only come in red, orange, yellow, white, and blue, because stars are approximately something called a "black body"). For example, our Sun is a yellow star with a surface temperature of 5,500 degrees Celcius (The Life of a Star).

        But why is this so? In order to understand that, I'm going to tell you about how stars live at all. This is what will determine the entire life of a star - something we'll be focusing on throughout this series. Two words: nuclear fusion.

        Nuclear fusion is "a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or absorption of energy." (Wikipedia) And this is where nuclear fusion gets REALLY important to stars. Throughout their lives, stars undergo nuclear fusion in their core. This is mostly in the form of fusing two or more hydrogen atoms into one or more helium atoms. This releases energy in the form of light (the pressure of nuclear fusion in the core also prevents the star from collapsing under the weight of gravity, something we'll get to later). The energy transports to the surface of the star and then radiates at an "effective temperature." (Britannica) 

        Stars are different colors due to differing amounts of energy. This is best explained by Einstein's e=mc2 or the mass-energy equivalence. In other words, the more mass something has, the more energy, and vice versa. Stars with greater mass undergo more nuclear fusion - and as such - emit more energy/temperature. And so, the bigger the star, the greater the temperature, the bluer the star; and the smaller the star, the lower the temperature, the redder the star (Universe Today). Another way to think about this is this: the hotter something is, the shorter frequency of energy it emits. Blue light has a shorter frequency than red light, and so, higher energy/temperature stars are bluer.

        Another important classification of a star is its luminosity (or the brightness, or the magnitude of the star). (The Life of a Star)

        The most famous diagram classifying stars is the Herzsprung Russell Diagram, shown in this article's picture. The x-axis of the diagram shows surface temperature, hottest left, and coolest right. The y-axis shows brightness, brighter higher, and dimmer lower. There are main groups on the diagram. 

        Most stars fall in a long band stretching diagonally, starting in the upper left corner and ending in the right lower corner, this is called the main sequence. The main sequence shows stars which mostly use their life going through nuclear fusion. This process takes up most of a star's life. Most stars which are hotter and more luminous fall in the upper left corner of the main sequence and are blue in color. Most stars that have lower-masses are cooler, and redder falls in the lower right. Yellow stars like our Sun fall in the middle. 

         The group located in the lower-left corner are smaller, fainter, and bluer (hotter) and are called White Dwarfs. These stars are a result of a star like our Sun one day running out of Hydrogen.

          The group located right above the righter's main sequence is larger, cooler, brighter, and a more orange-red or red, are called Red Giants. They are also part of the dying process of a star like our sun. Above them in the upper right corner are Red Super Giants, massive, bright, cooler, and much more luminous. To the left of the Red Super Giants are similar stars which are just hotter and bluer and are called the Blue Super Giants.

        That explains the most famous star classifying diagram. The important thing to remember is the data on the chart is not what a star will be like it's whole life. A star's position on the chart will change like our Sun will one day do.

        In a ThoughtCo. article on the Hertzsprung Russell Diagram, Carolyn Collins Petersen wrote: "One thing to keep in mind is that the H-R diagram is not an evolutionary chart. At its heart, the diagram is simply a chart of stellar characteristics at a given time in their lives (and when we observed them). It can show us what stellar type a star can become, but it doesn't necessarily predict the changes in a star." ( The Hertzsprung-Russell Diagram and the Lives of Stars)

        And this will continue to be important in the next chapters. Stars don't just stay in the same position their entire lives: they change in their color, luminosity, and temperature. In this series, we'll be tracking how stars form, live and die - all dependent on these three factors - and nuclear fusion - again - super important :)

Previous -  Chapter 1: An Introduction

Next -  Chapter 3: Star Nurseries

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It’s been two years, and I’ll never forget him.

I remember when I was little and I loved space, but I was worried that I would be too bored of the astrophysics area. Then I read Mr. Hawking’s book a Brief History of Time, and I fell in love.

Thanks, Stephie.

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The world lost an amazing thinker today. Celebrated world-renowned physicist Stephen Hawking passed away in Cambridge on March 14th, 2018 (Pi Day), at age 76. Somehow, I think he would have found this to be very poetic.

Stephen William Hawking CH CBE FRS FRSA was an English theoretical physicist, cosmologist, author and Director of Research at the Centre for Theoretical Cosmology within the University of Cambridge.

Omg particles are such players - JUST CHOOSE ONE!!!

But yeah wave-particle duality is kinda confusing sometimes lol

Like, how is it both? I dunno! Maybe I’ll read up on that later ...

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Photons : Hello I’m a particle . Oh yeah but i behave like a wave too , isn’t that beautiful !!

It surprises me how disinterested we are today about things like physics, space, the universe and philosophy of our existence, our purpose, our final destination. Its a crazy world out there. Be curious.

Stephen Hawking

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This was such a pretty poem that I had to reblog :)

But really, it’s 100% accurate. We are star-stuff.

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My favorite YouTube video as of now (I know this doesn’t seem like it’s related to space - but it has a nice discussion about black holes and hawking radiation, which is I love it so much)

Remember kids: be cautious of bouncy castles!

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Accurate

Even though it’s possible the apple thing never happened.

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Thinking intensifies

I swear every-time I see the quadratic formula I get the song stuck in my head

During math tests if you listen closely you can hear me mumbling

“oooooh x equals the opposite of b, plus or minus the square root, b squared minus 4ac all divided by 2a!”

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It was at this moment he knew…….

Bad Astronomy

The Bad Astronomy blog is all about real-world science — it covers the entire Universe, from subatomic particles to the Big Bang itself. Astronomy, space exploration, the effect of politics on science... you'll find it all here, as well as anything else that pops into the science-drenched brain of Phil Plait - astronomer, author and communicator. And you'll find it described with obvious joy and love for all things cosmic.

So I just finished re-watching Crash Course Astronomy - and I didn’t know that Phil had a blog :OOOOOOOO

Welp I know what my next read is gonna be

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