Theme: Stars

 

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Text, Viewspace. Coming up - Sail through the stars with NASA. A countdown clock counts down when the show will continue. The clocks starts at 15 seconds and ticks down to 0 seconds. Then the screen turns black. 

 

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 The Sun in space. 

Text, Our Sun is a star -- a gigantic ball of gas held together by gravity. 

Compared to the Sun, our entire planet is a mere speck. SUN. EARTH. 

A tiny blue dot hangs to the right of an enormous yellow sphere. 

Text, However, the Sun is not all that big in the realm of stars. 

Like most stars, the Sun is considered a dwarf star. 

A large blue star bumps the Sun away. 

Text, Other stars are much, much bigger. VEGA. 

A larger yellow star bumps Vega / away. 

Text, ARCTURUS. 

A larger blue star bumps Arcturus away. 

Text, RIGEL. 

A larger orange star bumps Rigel away. 

Text, ANTARES. 

A larger red-orange star bumps Antares away. 

Text, VY CANIS MAJORIS 

We skim the edge of the star. 

Text, The variety of stars in our galaxy is mind-boggling. 

A small yellow dot appears. 

Text, SUN. 

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A glowing red and orange nebula. 

 

Text, HUBBLE SPACE TELESCOPE. Pismis 24. In a nebula 8,000 light-years from Earth resides a small cluster of stars called Pismis 24. 

 

A cluster of large bright stars above the nebula gas. 

 

Text, The brightest star in this image is called Pismis 24 1. 

 

It was once thought to be as massive as 200 to 300 suns. 

 

A dotted line encircles the center, brightest star in the cluster. 

 

Text, This would have made it the most massive star known in our galaxy. 

 

However, high-resolution images from the Hubble Space Telescope reveal that Pismis 24 1 is actually three stars orbiting each other. 

 

Each star is about a hundred times more massive than the Sun.

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 Top left, a black and white picture of a minotaur. Top right, a color picture of stars. 

Text, MYTH versus REALITY 

Myth side 

Text, Stars are all the same. 

Reality side 

Text, There are a wide variety of stars in the universe, from red dwarfs to blue supergiants. They have different colors, temperatures, compositions, ages, masses, and sizes. 

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Stars and galaxies above a planet's horizon. 

 

Text, at-a-GLANCE. THE COLORFUL WAYS OF STARS 

 

Colorful stars dot into existence in space. 

 

Text, As you scan the night sky, you can find colors in the stars. 

 

Many stars appear white, but others are blue, yellow, red, or orange. 

 

Circles indicate colored stars. 

 

Text, A star's color depends on its temperature. 

 

A color bar spectrum. The visible light in the center expands. Wavy lines of purple, blue, green, yellow, orange, and red hang down. The waves are tight in purple and progressively loosen to red. Matching colored stars appear between the lines. 

 

Text, at-a-GLANCE. THE COLORFUL WAY OF STARS. ULTRAVIOLET. INFRARED. VISIBLE LIGHT. The hottest stars we can see appear blue. The coolest stars in the sky are red. Yellow or white stars (like our Sun) are temperatures in between.

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Text, Many stars live in groups, or clusters. 

Huge, spherical clusters of stars are called globular clusters. 

This is our galaxy's largest, called Omega Centauri. 

The Hubble Space Telescope has peered into the heart of Omega Centauri. 

There it found stars of different colors, sizes, and ages. 

There are many yellowish, middle-aged, Sun-like stars. 

Older, cooler, bloated stars appear orange. 

The red stars are even older, cooler, and bigger. 

The blue stars are the super-hot cores of very old stars that have cast off their outer layers. 

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A blazing orange star. Text, A star's fight for life. 

 

The horizon glows faintly under a night sky full of stars and the long pale mottled stripe of of the milky way. Text, When you look up at the night sky the stars seem peaceful and eternal. But the stars are alive, they are born and they die, sometimes catastrophically. To stay alive, stars must fight a constant battle against gravity, a battle they ultimately will lose. 

 

A three dimensional nebula in space, a pale yellow cloud colored purple, red, and green at the edges, filled with glowing stars. Text, Stars are born in giant clouds of gas and dust called nebulae. Gravity builds a star by drawing gas together tighter and tighter. An animation of small particles floating in reddish gas. Text, When a clump of gas gets hot and dense enough, hydrogen atoms smash and fuse together forming helium and releasing energy. the particles collide and combine, and small waves and particles of energy are released. Text, A star is born. A glowing spherical object in the clouds. Yet gravity doesn't give up once a star is born. An animation of arrows pushing inward in a ring around the star. Gravity relentlessly works to crush the new star ever smaller. However, the star fights back. Arrows push outward from the rim of the star. Its fusion of hydrogen to helium releases energy which applies an outward pressure. 

 

This counteracts the inward crush of gravity. As long as the star keeps fusing atoms, it stays alive. 

 

A star's lifespan and its ultimate fate depend on how massive the star is. with more mass comes more gravity. 

 

The most massive stars go through nuclear fusion at greater rates than smaller stars, allowing them to resist the greater gravitational stress they're under. 

 

They run out of fuel much faster than less massive stars. When a massive star runs out of nuclear fuel, gravity takes over and the star's core collapses. 

 

The animated star shrinks and bursts into white light. Text, The collapse generates tremendous amounts of energy which blows the star apart in a supernova explosion. The white dissipates into space. Text, The most massive stars can exhaust their fuel and explode after just a few million years of life. 

 

The daintiest of stars however can live for many billions of years. 

 

In fact, in the 13.7 billion year history of the universe none of the least massive stars in the cosmos has died. A small orb glowing deep red. We do not know how these stars will end their lives. 

 

Our sun is between these extremes. It will live for about 12 billion years in total. When the sun runs out of hydrogen to fuse, gravity will start to take over and crush our star. 

 

The pressure will turn up the heat inside the Sun, starting new nuclear reactions in its center. 

 

These new nuclear reactions will fight back gravity, and the star's outer layers will expand, turning the Sun into a "red giant." 

 

Text, eventually, the star will lose its gravitational grip on these outer layers and they will gently float away. 

 

Meanwhile, the core of our sun will be squeezed by gravity to the size of planet earth. 

 

this stellar remnant, called a white dwarf, will slowly cool down. 

 

Our sun will send the rest of its days as a victim of gravity and a phantom of what it once was. A small white glowing sphere.

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 Top left, a black and white picture of a minotaur. Top right, a color picture of stars. 

Text, MYTH versus REALITY 

Myth side 

Text, Stars live forever. 

Reality side 

Text, All stars eventually die. Some stars live for billions or trillions of years, but others live for just a few million years. 

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A starry sky over a forest. 

 

Text, STARS IN OUR GALAXY. Milky Way. 

 

All the stars we see from Earth's Northern Hemisphere belong to our Milky Way Galaxy. 

 

In a remote location away from city lights, we can see up to a couple thousand stars. 

 

But our galaxy is home to hundreds of billions of stars. 

 

Beyond our galaxy are hundreds of billions of other galaxies, each one containing billions of their own stars.