{tangent} - BIRTH STARS!! and SAVE ALL THE WHALES!!

Firstly:
Stars are really really far away. The Sun is the closest star to us, and its 92.96 million miles away. Since light actually travels at a speed, 670,616,629 miles per hour, it takes an entire 8.317 minutes for light to travel this distance from the Sun's surface to our eye here on Earth. This means that if the Sun were to suddenly vanish, we wouldn't even know about it for 8.317 minutes (check out this video for more on what would happen Lights Out http://www.youtube.com/watch?v=rltpH6ck2Kc). The next closest star to us is Proxima Centauri at 29.943 trillion miles away. This is an easy one to remember because the word proxima means nearest to.

{The bright one on the left is Alpha Centauri} 

This is so far away that its better to define its distance from us in light years, the distance that light travels in a year. Light takes 4.243 years to travel the 29.943 trillion mile distance from Proxima Centauri to Earth, making it 4.243 light years away. This also means that the light we see when we look up at it tonight is 4.243 years old. 

The most distant object in the night sky is galaxy z8_GND_5296 at 13 billion light years away. For more on this check out Star Far (http://www.science.tamu.edu/news/story.php?story_ID=1129#.UyFGslFdUpw).

So when you look up at the night sky beyond our solar system your actually looking from 4.243 years to 13 billion years into the past. Some of the stars that we see when we look up have actually long since died out (maybe thats why your wishing star hasn't come through for you). What the stars actually look like at the instant of looking up can only be estimated using astrophysical generalizations and formulas that project age progressions of the stars. If 70 light years away there were an alien that could see and zoom in on Earth, it would see war and genocide. If it were 66 million light years away, it would see dinosaurs and think of earthlings as giant creatures with short arms, having no idea of the catastrophe that would soon hit and make way for human evolution. If you go even further, anything looking at Earth from more than 3.8 billion light years away, which is the majority of the universe, wouldn't even know that there was life on Earth.
Side note: If we ever do figure out how to create warp drives or move faster than the speed of light, we'll be able to blast out to the necessary distance and aim our super advanced telescopes at Earth then watch Babe Ruth sliding home, or even a real Shakespearean play, We could even settle historical questions of religion.
Its kind of wild to try to conceive. We instinctually think of visual images as one instant, but what applies when we look at the stars applies when you look at anything. Things in our three dimensional realm all very in distance to us, so light that hits your eye from one object originates fractions of a second apart from that of another object. Therefore when you look around at things, you are looking at different times and actually perceiving a calage of both time and space. Images, in brain and on paper, in fact aren't true moments, they are moments of perception.

Sorry, that was a rather abstract rational all to get you ready for this link that will tell you what star is as many light years away from us as you are old. 

Birth Star

http://outreach.jach.hawaii.edu/birthstars/year.php

If you are 22.1 years old the light from a star 22.1 light years away will just be arriving now and left the surface of the star 22.1 years ago, the day you were born. I think its pretty cool. If your birthstar is visible overhead then you can look up at the star at light that is basically as old as you are. In other words, you are getting a look at the time you were born.

Secondly:

For those of you who read my recent post Indian Givers on death by asteroid impact and thought to yourselves, "I've got to do something about these asteroids:"
Nastaroid     http://www.bbc.com/news/technology-26528516
Nasa is looking for coders to help prevent the Earth from being smashed by an asteroid. If you identify a particularly threatening one from a ground based telescope, they'l give you $35,000. Get to it

Next Time On An Existential Universe - DEATH BY GAMMA RAY BURST!

Out of all catastrophic forces that spawn out the depths of this insane universe, the ones that haunt me most are those that mover near the speed of light. We can predict weather or not we will collide with comets and galaxies based on observations and calculated trajectories, but e can’t predict catastrophe from forces moving at the speed of light. By the time we observe a catastrophic force moving at nearly the speed of light we would have already been experiencing the force itself, rendering predictions pretty futile. Put your tin foil hats on, gamma rays are coming.

The Indian Givers - DEATH BY ASTEROID!!

{this didn't happen}

To look at the Moon say that it's made of cheddar cheese would be ridiculous. Obviously its made of swiss. Even in broad daylight we can make out the large craters and different shadings of the Moon that give it its swiss cheese affectation. These are scars left behind by the impalements of asteroids. If an asteroid can create a crater 2240 kilometers wide and 13 kilometers deep on the moon, what can one do to Earth? 

Watching science fiction movies like Deep Impact and Armageddon will instill the fear of death by asteroid into anybody. These movies may be fictional, but they do depict catastrophic events that can really happen. The Moon's surface area of 37.9 million square kilometers is only 7.4% of the Earth's 510 million square kilometers. From this we can estimate that for every two asteroids that hit the Moon, roughly 27 hit Earth. Given the gravitational differences between the two, its actually more like 1 asteroid hit on the Moon is 50 or 60 on Earth. The reason that Earth is not 50 times more scarred than our moon, is that Earth has a defense shield - its atmosphere. Earth's atmosphere is way more dense and way larger than the Moon's. This means that when an asteroid comes into contact with Earth's atmosphere it faces much more impactive and frictional forces than it would in the Moon's atmosphere. Due to this, most asteroids that come to Earth either burn up before they hit the ground or combust upon hitting the atmosphere and then sizzle away. Many of the shooting stars we see at night are grain sized asteroids burning up in the atmosphere.

The differences are between asteroids, comets, and meteors are pretty subtle.

Comet: Comets are also relatively small and orbit the Sun. When close to the SUn, the solar radiation creates a coma around them. Here's a picture of "The Comet of the Century", Comet McNaught 

Meteoroid: A small rock or particle in the solar system. They can be the size of dust to around ten meters in diameter (anything larger is usually considered an asteroid).

Meteor: When a meteoroid passes through Earth's atmosphere is burns up and becomes a meteor. These are known as shooting stars.

Meteorite: A meteorite is whats left if a meteoroid makes it all the way through the atmosphere and survives colliding with Earth's surface.

Asteroid: Relatively small bodies of rock and metal that orbit the Sun. They can also carry organic compounds such as water. Asteroids are similar to comets, but they don't have a visible coma (the outline and tail).

Molecules collide and form particles. Particles collide and form dust. Dust collides and forms small asteroids. As the trend continues, asteroids collide and form bigger asteroids. Bigger asteroids begin to attract dust and small asteroids as they collide with other large asteroids. The trend continues on. Asteroids get become large enough to have moons or even be called pre or dwarf planets. The largest asteroid in the asteroid belt is Series which is 600 miles in diameter and contains a large amount of ice. Its molten core makes it a great prospect for extraterrestrial life. For more info on this and the asteroid belt check out this link about the Dawn probe: Dawn (http://dawn.jpl.nasa.gov/). Eventually an actual planet is formed. This explains the genetic material of Earth and the other 3 rocky planets. Here's a cool visualization of the process : 
Birth Earth
http://www.youtube.com/watch?v=mEuSXjpWnIQ

Asteroids not only constructed our home, they gave it one of the most essential resources of life, water. Four billion years ago, Earth and the Moon went through what is called the Heavy Bombardment period; a period when millions of asteroids rained down on Earth, creating perilous earthquakes and hurricanes as they delivered most of water here today. This period is also responsible for most of the indentations on the Moon.  What gave life can also take it. A large enough asteroid collision can definitely devastate life on Earth. This has happened in the past. Take a look at the Arizona crater and you'll see how powerful these things are. It follows that with more size comes more carnage. A 50 yard asteroid can take out a city. A half mile asteroid can take out the world. This has already happened. Take another look around Arizona and you'll see that there aren't any dinosaurs. 
You can actually dig down into the ground and see the deposit left behind by this large asteroid. This layer is called the KT boundary and marks the end of the era of the dinosaurs 66 million years ago. The layer is rich in iridium, an element thats abundant on many asteroids and extremely rare on Earth. On top of the iridium is a thin film of ash deposited by the flaming turmoil that was Earth after the impact.
Digging further down, you can find more of these layers. Geologists estimate that large asteroids hit Earth every 16 to 100 million years, meaning that we should be expecting an asteroid to be headed our way right now, ready to burn every mark of us out of existence and leave our home planet to the cockroaches. Here's a dazzling video that simulates a large asteroid impact on today's Earth:

Roided Roid

http://www.youtube.com/watch?v=PENT_hnyO-o

Luckily we are a little more advanced than our dinosaur predecessors and have the ability to look into space and find asteroids headed towards us. In fact, we were able to deem asteroid 2014 DX110 non hazardous before March 5 when it passed by within one lunar distance from us (here's an article on it: Close One http://www.slate.com/blogs/bad_astronomy/2014/03/05/asteroid_2014_dx110_tiny_rock_will_pass_the_earth_today.html). But we are not safe yet. We found an even bigger, 300 meter, asteroid that is headed right at us, its name Apophis - god of death. Here's a very informative article all about it: Hide yo Earth http://neo.jpl.nasa.gov/apophis/. In 2029 it is estimated to pass closer than the moon, and yet even closer when it comes back around in 2036. Check out Neil Degrasse Tyson describing what would happen if it hit us: Die Another Day

http://www.youtube.com/watch?v=w4l7KB3qkYg

Fortunately, researchers were able to use the Arecibo Observatory, the worlds largest radio telescope (1000 ft aperture), to determine that Apophis will most likely not hit us. Unfortunately this telecope was recently damaged in earthquakes that transpired in January.

However, most likely means that there is still some likelihood that of impact. In fact there is a 1 in 45,000 chance that it will. Not too much at all, but kind of a lot considering that all of humanity is at risk. 
Predicting is one thing, preventing is another. You can watch Neil DeGrasse Tyson talk about this here: 

Neil DeGrasse Tyson - How to Deflect a Killer Asteroid

Construct Additional Pylons

http://www.youtube.com/watch?http://www.youtube.com/watch?v=1-ReuLZ2quc&index=4&list=PLdZH0MmaSA_SuE2GUv1ptvFwvkljF2PaL
Essentially, we will eventually be smashed if we don't get off this planet or figure out a way to prevent asteroid collisions. Blowing up a large asteroid coming at us will just create many small asteroids coming at us, which just makes smaller targets. The most effective way to prevent collision is to slow down or speed up the asteroid. If we know that the Earth and asteroid will be at the same location at the same time we can try to make one of them pass through that location first. We could accomplish this with a gravitational leash where we use the gravity of a space ship to accelerate an asteroid. Due to the lack of any real threat, there are only preliminary designs for such a spacecraft.
Someday we will have such space craft. Humanity will be able to leash asteroids and control their positions, not only ensuring the safety of Earth, but capturing a vessel of resources. Asteroids are packed with rare materials that are very valuable on Earth. Obama has commenced plans for Nasa to reach its first asteroid by 2025. Eventually we will be able to create space stations on asteroids and exploit them for resources and shelter. They will become our stepping stones to the final frontier as well as our gas to get there. 
Asteroids formed our planet, brought life to our planet, and soon enough will provide the means for life to leave our planet. As far as I can conclude, we are now entering an age of such achievement that asteroids no longer threaten us but engage us into progression. 
We are actually pretty lucky to have not had any large disasters come about from asteroids. Its pretty wild to think that with respect to the cosmic clock, we are just barely gained the capabilities of asteroid prediction and are on the verge of impact prevention. In a universe of such immense possibility, asteroids could have completely erased any any trace of a civilization that grew to be as advanced or any less advanced as we are right now. Two hundred years ago we would have had no idea that an asteroid was headed towards us, then suddenly one hits causing both our species and lifestyle to change, assuming they are not obliterated. Then again, by 2036, I'm pretty sure that well be able to stick a fat straw into Apophis, the so called god of death, and say thanks for the resources before it even comes close to threatening us. 
Bring em on

If you're into space documentaries, here are links to my favorite ones about the threat of asteroids:

How the Universe Works: Asteroids - Worlds That Never Were

Roids

http://www.youtube.com/watch?v=FUdeGi3Ae1Y

This documentary completely describes everything you need to know about asteroids.

Hyperspace: Staying Alive

Live and Let Asteroid

http://www.youtube.com/watch?v=KrmNR30vGp8&list=PLB4E684D4F4DBD978

Analyses the chances of Earth being destroyed by a black hole or asteroid.

The Known Universe: The Most Explosive

Boom

http://www.youtube.com/watch?v=UwejGdnnYJM

From exploding stars to asteroid impacts, Known Universe deconstructs some of the biggest explosions in the universe with some pretty sweet CGI and slow-motion footage.

The Shining - DEATH BY SOLAR CONSUMPTION!

As the Sun gets older, what disastrous threats will the it bring forth against not only the home of mankind, but the very survival Homo sapiens itself?

{Not Drawn To Scale}

“We all shine on

Like the moon and the stars and the sun

Come on and on and on…” –John Lennon, Instant Karma

I like to think that, regardless of whatever great forces of death we inevitably face, we all shine on and on and on in one way or another. As far as the Sun goes, I’m sorry John Lennon, it will shine come on and on and then it won’t. The Sun has burnt through about half of its hydrogen supply; when it’s done with the other half in about five billion years, it will drastically change prior to fading away. Maybe John Lennon was right; maybe we shine on exactly like the Sun; maybe when the Sun stops shining on, we will too.

Come the end of their lives, stars way bigger than the Sun detonate under their own forces and create supernovae. Typically when this happens, they sling most of their residential planets way out of orbit and into space. These planets then become what are called rogue planets, or planets that are not bound to an orbit. These planets are particularly hard to find since they are not very bright and don’t regularly eclipse stars. Dr. Michael Liu and his team at University of Hawaii recently found the rogue star J318.5-22 at roughly 80 light-years away. In his excitement after finding it he said, “We have never before seen an object free-floating in space that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone."

When stars similar to the Sun deplete their nuclear fuel in their cores they swell up into red giants. When experiences this in five billion years, it will definitely grow to a size so large that it swallows the inner planets, Mercury and Venus, and maybe even so large that it engulfs Earths orbit as well. Theoretical physicist Eva Villaver at el Universidad Autónoma de Madrid describes two things that could happen to Earth when the Sun reaches this stage. The Sun could hurl its outer layers past us, and deep into space (creation of a planetary nebua), causing Earth to end up in a wider and safer orbit outside of the Sun’s bite. At the same time, the Sun’s tidal forces that would pull Earth inward could counteract this, causing Earth to be eaten by the Sun. Villaver says, “We don't know which effect will be strongest.”

Several factors make the fate of the Earth even harder to predict. The influence that the planets will have on the Sun during its evolution is one of them. The Sun will increase the energy in its outer layers after swallowing Mercury and Venus. This not only generates uncertainties in how much matter the Sun could expel past Earth, but also those on what the tidal forces will be like. Tidal interactions with Earth will dump more energy into the Sun’s outer layers. These surges could cause the Sun to shoot even more matter into space. While this may give Earth a safer orbit, its magnetic field, which acts as a shield, will certainly not be able to keep Earth’s surface protected from all of the Sun’s projections. The magnetic shield is definitely not anything that could protect Earth against Mars. According to astrophysicist Boris Gänsicke of the University of Warwick in Coventry, Earth may be pushed back into an orbit that intersects with that of Mars, causing the two planets to splinter into trillions of asteroids. This stage of the Sun’s evolution could will completely change the surface conditions on Earth, and maybe even conditions within Earth as well.

The tidal forces caused by the Sun’s swelling could be so great that they cause the Earth to periodically expand and contract, generating an insane amount of internal stresses that will lead to the Earth heating up.

Io is my favorite moon and a pretty sweet example of a celestial body under crazy tidal forces, making it an example of what Earth could come to during red giant stage of the Sun. Io is one of the four Galilean moons (moons discovered by Galileo) that orbit Jupiter. With more than 400 active volcanoes, it is the single most geologically active celestial body in our solar system. Io’s volcanoes blast plumes of sulfur up to 500 kilometers into the atmosphere. Its silicate crust has been uplifted into more than 100 mountains, a few of which are taller than Mount Everest. This insane amount of geologic activity is derived from tidal heating that’s caused by internal friction created by the tugging and pulling effect of tidal forces.

Io was named after the Princess of Argos, a mythological character who Zeus fell in love with. To keep Hera from finding him seducing Io, Zeus covered the world with a thick blanket of clouds. This only enticed Hera’s suspicion. As she began to disperse the clouds, Zeus improvised and quickly turned the lovely princess into a cow. He then testified that he knew nothing of the cow and that it sprang right out of the Earth.

Io’s name is quite fitting for a moon of its characteristic. Its volcanoes not only project dark clouds into the sky, but they produce lava flows that change the appearance of the moon, coating it with yellow, red, white, black, and green allotropes. It has gushes lava flows that leak all over the place, some reaching over 300 miles in length. Io’s volcanic ejecta even interacts with Jupiter’s magnetosphere and creates what is known as a plasma torus, basically a cloud of gas and plasma, that encompasses Jupiter.

*This guy Larry Niven wrote his novels The Integral Trees and The Smoke Ring wherein a giant gas planet orbitting a neutron star generates a gas torus dense enough to sustain human life. This is completely implausible

This is only modest for what tides could actually do to the Earth. If powerful enough, they could shred the Earth into a trillion fragments.

Even if Earth does survive the Sun’s Red Giant phase, it is only in futility, for the doom of life on Earth is lurking in the next stage of the Sun’s evolution.  As the Sun ages into its next phase, it discharges its outer layers into deep space and then compacts into a white dwarf star. Eric Agol of the University of Washington asserts that Earth-sized planets can actually end up close enough to a white dwarf where they can exist in habitable temperatures for billions of years. In fact, several examples of this have been found.

On the other hand, if Earth ends up in a trillion pieces, its remains could either rain down into the atmosphere of the white dwarf Sun, or create a disk around it. This happened to a solar system that’s only 50 light-years away. Gänsicke talks about how white dwarf GD61 has an excess of oxygen in its atmosphere that could be remnant of an Earth like planet that did not survive its physical changes.

Agol also thinks speaks of second-generation planets that form in the ring that surrounds a white dwarf, “We can't exclude that a second generation of rocky planets might form from these disks.” This means that the very fragments left behind by previously destroyed worlds can smash into each other, accumulate, and resurrect into new worlds

 “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”  - Carl Sagan, Cosmos

In this, in some kind of an abstract reincarnation, we do shine on and on and on. Not even the tremendous power of the universe can completely erase matter. It gets broken down and transformed but not erased. What was the Earth and you and me gets recycled into something else which then shines on until the time has come for it to be recycled into something else that will shine – unless it’s a black hole, they’re black and not very shiny – an existential universe.


Here is a really interesting video on what the Earth would be like if the Sun were to suddenly vanish. 
Night Night
http://www.youtube.com/watch?v=rltpH6ck2Kc

Death By SOLAR STORM!

Here is a link to an episode of Cosmic Journeys called "Attack of the Sun". Its a 24 minute video all about stuff that the Sun shoots at us. They go into great detail about solar flares and coronal mass ejections while describing modern research on the subject.
Yellow Rum
http://www.youtube.com/watch?v=fMUHkz5nx8g

The Sun follows an eleven year cycle that is currently in its solar max, the portion of the cycle when the Sun is most active and has the most solar storms. During a solar storm the Sun releases tides of electromagnetic radiation and coronal mass ejections. A coronal mass ejection, or CME, is essentially a large bubble of plasmic gas that is threaded with magnetic field lines. When CMEs reach Earth they release their energy and visibly create colorful auroras. As pretty and amicable as the auroras are, they are tied to the force of CMEs which can unleash static discharges that disrupt, or even destroy, out power grids. The Sun also releases solar flares, basically eruptions of supercharged protons, that can reach earth in minutes, reaping calamitous consequences.

Solar flares occur on the surface of the Sun and can last anywhere from minutes to hours. A large flare can release enough energy to power all of the U.S. for a million years. Solar flares typically occur in the most active regions of the Sun, such as sunspots, where the magnetic fields are strongest. A solar flare is generated by the magnetic fields within and around the Sun. When the field lines extend out of the Sun's surface, they can carry plasma with them. Stresses on the surface of the Sun can cause the solar flares to twist and make contact with their positive and negative poles. This causes a huge explosion that pulses out into space.
Flares are classified by their strength. An X1 class is at least ten times more energetic than an M1 class which is ten times more energetic than a C1 class, which in turn is ten times more energetic that a B1 class flare.

B and C class flares are not strong enough to effect Earth. M class flares are known to generate radio blackouts and radiation storms. The X class is the real oppugner. The most powerful flare every recorded was measured in 2003 during the last solar maximum. The flare was so powerful that it overloaded the sensor that measured it. NASA calculated it to be an X45, which means that it was 45 times more energetic than an X1. A flare of this magnitude can generate long lasting radiation storms that harm satellites and potentially give small radiation doses to airline passengers flying near the North or South Poles. These flares are known to create blackouts and global transmission issues.
This great potential is what inspires NASA to constantly monitor the Sun. Using their Heliophysics fleet of spacecraft, NASA nonstop looks at every side of the Sun through many wavelengths. This extensive coverage allows NASA to predict solar storms, allowing protection against the worst consequences of the Sun.
According to NASA, our power grids are now interconnected to the point that a large solar storm could generate failures that would cut power to 130 million people in the U.S. alone. This would have fiscal repercussions in the trillions of dollars and take years to fix. Communication would be cut off, international trade would slow, millions could die, and this blog will not be accessible. The last large solar storm that Earth experienced was in 1889 when a solar storm cut out all power to all of Quebec. Thirty years before that, a solar storm caused telegraph wires to short out all across the U.S. and Europe.
While we may have integrated electronics into our lives far more than in the day of the telegraph, the death force of a solar storm is most likely not strong enough to wipe out humanity. NASA tells us that the solar max that Sun is currently in is nothing to be afraid of and that their is no special risk associated with it.

Here is a link to a video that describes solar flares:

Solar Flares
http://www.youtube.com/watch?v=nmDZhQAIeXM

This link will take you to a video made pre-2012 about the solar max and what that means for the sun:
Just the Beginning
http://www.youtube.com/watch?v=d_uBlDoecak

Here is a link to a video that describes the M class solar flare that hit us this year on the 27th of January. Skip to 2:20
Smooth Solar Sailing
http://www.youtube.com/watch?v=C8KHy3Df_Xw

Our first foe - THE SUN!

"Death comes to all, but great achievements build a monument which shall endure until the sun grows cold." - Ralph Waldo Emerson

Our closest threat is the Sun. Life on Earth is completely dependent on the Sun. It feeds us, keeps us warm, and tucks us in to a safe place in the galaxy. Life would be much harder to maintain if we were closer to or further from it. The Sun is a massive 1,969,000,000,000,000,000,000,000,000,000 kilogram ball of 70% hydrogen 28% helium that is 1,390,000 kilometers across. Its core is 15,600,000 Kelvin and its surface is 5,800 Kelvin. Basically, its a humongous sphere of fire, plasma, and radiation. Nuclear fusion in its core produces its 386 billion billion mega Watts by converting about 700,000,000 tons of hydrogen to about 695,000,000 tons of helium and 5,000,000 tons of energy (gamma rays) - every second! The fragile balance of the Earth-Sun orbit combined with the extreme energy of the Sun makes the Sun a pretty laudable force that can turn against life on Earth.

The Sun is huge. It contains more than 99.8% of the total mass in our solar system. Jupiter contains most of the rest. Its easy to see that the Sun emits light and heat, but it also emits a low density stream of electrons and protons in what is known as the solar wind. This wind spreads out in our solar system at about 450 kilometers per second. Data collected from the spacecraft Ulysses has shown that the solar winds can be up to 750 kilometers per second. The solar wind creates the large tails on comets and can generate measurable effects on the trajectories of spacecraft. Additional information about the solar winds will be gathered by the recently launched Wind, Ace, and SOHO spacecraft which will be positioned 1.6 million kilometers from the Earth towards the Sun. The Sun is also know to eject high energy particles in what are called solar flares. Both the solar wind and solar flares can greatly affect Earth; they can cause radio interference, aurora, and even power line surges.
At 4.5 billion years of age, the Sun has already used up about half of the hydrogen in its core. The other half of its hydrogen supply will allow it to radiate for another 5 billion or so years, but as ages it will gain luminosity and become approximately twice as bright by the end of its hydrogen supply. When the Sun has fused all of its hydrogen it will radically change, and possible completely destroy Earth, but nevertheless create a planetary nebula where new planets can be born.

Before we look at what this adversary can do to us, lets look at what it really is and what it can do. The sun is one of more than 100 billion stars in our galaxy. Here's a really cool video done by the Discovery Channel that describes the life cycle of stars from birth to death:
Twinkle Twinkle BOOM
http://www.youtube.com/watch?v=4s7vyDLgk3M

To summarize it all up:
Nebulae (interstellar clouds made up of dust, hydrogen, helium and other ionized gases) are the procreators of stars. These gargantuan clouds eventually collapse under their own gravitational forces and form protostars. The protostars continue to collapse and become main sequence stars. As the star ages it fuses its hydrogen into helium and helium into heavier elements. Eventually the core runs out of hydrogen and later helium. This cause the core to contract and the outer layers to expand and cool making the star less bright. At this stage the star becomes a red giant or even a super red giant if it had enough initial mass. It then collapses a final time and explodes, becoming either a black dwarf (a white dwarf that has cooled and no longer emits large amounts of heat or light), neutron star, or black hole.

In more detail:
Nebula - gas and dust clouds in the cosmos. They are where stars are born and are composed of the very matter that makes the stars. There are multiple types of nebula. The Orion nebula is an emission nebula the shines overhead come winter due to the gas in it being energized by stars that have already been created within it.

In a reflection nebula light from stars is reflected of the grains of dust within the nebula. The Pleiades Cluster is an awesome example of a reflection nebula.

Dark nebula, like the Horsehead Nebula in orion, are denser clouds that can absorb a fraction or all of the light emission from behind them.

A planetary nebula consists of the outer layers that a star sheds when is changes from a red giant to a white dwarf. Here is an image of the Helix Planetary Nebula

Stars - luminescent sphere of gas that produces its heat and light by nuclear fusion. Stars are composed of mainly hydrogen and helium gas. They can have surface temperatures from 2000 K to hotter than 30,000 K. Their colors correspond to their surface temperature and range from red to a blue-white.

The most luminescent stars can emit as much light as a million Suns and have masses 100 times greater than the Sun. These stars have short lives and live for less than a million years until the die a glorious death and supernova. On the other hand, the dimmest of stars are red dwarfs; the Sun is a thousand times more bright than them. While the smallest possible mass of a star is 8% that of the sun, it is still about 8000% the mass of the biggest planet in our solar system, Jupiter. At any small of a mass, the gravitational forces wont be enough to entice nuclear reactions. Celestial bodies with masses less than this critical mass are dim and deemed either brown dwarfs or large planets.

Red Giant - large bright and cool (cold) star. These form later in the life of a Sun like star when it has exhausted its hydrogen. They usually have diameters 10 to 100 times larger than the Sun's. Their luminosity comes from their huge size. Very large red giants are called super giants and they have diameters up to 1000 times that of the Sun with luminosities 1 million times greater than the Sun's. Check out Mira in Cetus the Whale

Red Dwarf - small, cold, and faint stars. They are about 10% both the mass and diameter of the Sun. These burn their fuel very slowly and live about 100 billion years. Check out Proxima Centauri

White Dwarf - small, hot star. A white dwarf is a Sun like star in the last stage of its life cycle. They weigh about the same as the Sun but have only 1% of its diameter. Thats about the size of Earth. This gives it an insane density. A spoonful of a white dwarf would weigh several tons. On their surface they are about 8000 K and only have a luminosity of about a percent of the Sun's. Essentially a white dwarf is the shrunken remains of what it used to be. They have no more nuclear energy and live out the rest of their lives as degenerate matter as it cools and fades over billions of years. Here is a picture of the first one ever found. It lies in the triple star system 40 Eridani

Supernova - explosive euthanasia of a star. Supernovas lead to the star reaching a brightness of about 100 million Suns for a brief period. They are the main source of elements heavier than hydrogen and helium since they produce enough heat and energy to fuse them.
A type one supernova will take place in binary star systems where the gas will be expelled from one star as it is sucked onto a white dwarf. This causes the white dwarf to explode.
A type two supernova takes place in star that are ten times the mass of the Sun. These stars experience runaway internal nuclear reactions that lead to explosions. This type of supernova leaves behind either a neutron star or a black hole.

Neutron Stars - stars made of neutrons. When a supernova explodes it forces protons and electrons to combine and form a neutron star. These are very dense stars. Neutron stars that spin very rapidly create the blinking effect of a pulsar.

Neutron stars typically have a mass three times that of the Sun but only a 20 kilometer diameter. Any greater of a mass will generate a gravitational force so great that a black hole is formed. 

Black Holes - form from massive stars. Black holes have a gravitational pull so great that not even light can escape it. They are so powerful that they distort the space continuum around them. When active, black holes sick in stars and even galaxies around them. There is a black hole at the center of most galaxies, including our Milky Way, and a supermassive black hole at the center of the universe. Here is an image of a black hole distorting the light from behind it

Here's a cool video on the ways a star can die:
Exploding Stars:
RIP

http://www.youtube.com/watch?v=qfRiqwQBegQ&list=PL6667B34B30CADD6D

Here is a link to a video that will prepare you for the next blog post about the dangers posed by solar flares and coronal mass ejections. The video is a NOVA special on the Sun called "Secrets of the Sun". Its 52 minutes of information about the Sun's behavior and how it works. NOVA looks at current research on the Sun including the launch of the Solar Dynamics Observatory which will give us uninterrupted coverage and high-resolution observation of the Sun. It also includes a really interesting portion on what we can learn from the sounds that the Sun produces.  
Hot Tamale

www.youtube.com/watch?v=wisdfag6WIQ
"Unimpeded, the trip from the core to the surface would take the photons a matter of seconds. In reality, the sunlight that shines on us today may have been created during the last ice age. Energy reaching the sun's surface doesn't just result in sunlight. It can also trigger solar storms."- Watch it and find out how

A look at the universe - BEFORE IT DESTROYS EARTH!

Here is a link to a portion of the iMAX movie "Cosmic Voyage":
So Big
http://www.youtube.com/watch?v=qxXf7AJZ73A

This zooms out from 1 meter on earth and defines sizes of familiar objects at intervals of 10 to the power of n meters until we get to the size biggest thing we know of, the universe. It then zooms in again defining sizes of familiar objects at intervals of 10 to the power of -n stopping at the size of the smallest thing we can currently define, quarks. This covers 42 orders of magnitude over all. It helps generate the realization of how absolutely colossal the universe is and how it contains so many of these truly minuscule things. With such an immense size and energy, there is immense potential for things to come out of the chaos and destroy our Earth. Its a really cool and very well done video, and most importantly, Morgan Freeman narrates it. Check it out.

A look at Earth - BEFORE THE UNIVERSE DESTROYS IT!

Before we try to blow it all up with cosmic forces, here's a cool video to give us a look at Earth as it is now:

Earth Time Lapse from Space

http://vimeo.com/32430473

This takes us on seven minutes of time lapses of Earth as viewed by the International Space Station 250 miles above Earth while orbiting at 17,500 miles per hour. You get a pretty good view of California at about 5:22. This definitely forces perspective on how incredible our home planet is. You can see some really sweet shots of lightning the auroras from space. You can also see all of the light pollution generated by night lights in cities and towns and begin to understand the impact that humans have on our planet.

This next video really helps visualize Earth's place in the universe:
Where We At?
http://www.youtube.com/watch?v=mswhI90zNF4

This really makes you think about how tiny the Earth is relative to other things in the universe. Its hard for us to conceptualize the biggest buildings that humans have built, much less the Earth itself, and even less so Jupiter, the solar system and so on. We consider the force of the ocean's waves incredibly strong, but when compared to the forces of the cosmos, they are nothing but feeble little tickles.

Here is a link to a youtube video of 5 experiments that had the potential to destroy Earth.
Death to Earth
http://www.youtube.com/watch?v=A9S9gwhS6Yk

Its pretty wild to think that some experiments that we don't even know are going on could change life on Earth. Knowledge gained from these experiments is very valuable, but nonetheless they were risky. While we may have figured out how to easily destroy life on Earth, it will be a lot harder to destroy the Earth itself.