For The Heliosphere go to https://youtu.be/1oDUN74yzuo

the Sun is moving through the Galactic medium like a ship in the ocean and we're just tagging along as we talked about earlier the Sun is a thermonuclear fireball that's continually ejecting large quantities of high-energy particles into space this is the solar wind and it goes out in all directions the extent of the solar wind defines the final frontier of the influence of the Sun it's called the heliosphere the solar wind strength dies down as it spreads out over increasing volumes of space once it equals the strength of the interstellar wind coming from the rest of the Milky Way a stalemate is reached this point is called the termination shock the high velocity particles from the Sun come to a veritable standstill in a stalemate with the rest of the galactic medium a wide area of space where that transition from solar wind to galactic wind occurs is called a heliosheath or Helio pause and like ocean water being pushed aside by the bow of a great ship the Sun with its solar wind does the same in the galactic medium that's why they call the final boundary the bow shock this marks the final extent of the solar wind and defines the outer limits of the heliosphere unlike other objects in the solar system that can be seen and triangulated to determine how far away they are the only way to find out how far away the termination and bow shocks are and therefore how to calculate the size of the solar system is to go there measure which way the wind is blowing and report back how far you've gone this is exactly what Voyager 1 and Voyager 2 have done launched in 1977 both spacecraft have passed through the termination shock voyager 2 is currently deep into the heliosheath I'll tell you where Voyager 1 is a bit later in this segment we now know that the heliosphere is not exactly a sphere it is squashed by the Galactic women at the squashed end we know it extends to around 11 billion miles from the Sun that's 118 times further than the distance between the Earth and the Sun it takes light around 16 hours to get from the Sun to the heliosheath nasa's goddard space flight center in cooperation with international partners manages a fleet of spacecraft monitoring all aspects of the heliosphere this fleet is called sentinels of the heliosphere the grey mesh around the earth that you see is called the magnetosphere it's the Earth's magnetic field pushed back by the solar wind it's critical for life on Earth because it routes charged particles in the wind around the earth instead of letting it bombard us head-on that makes it very important for us to understand here's the near-earth fleet is monitoring solar activity and orbiting Earth every 92 minutes [Music] now we are taking a look at the geo space fleet that orbits deep into and around magnetosphere cluster is a group of four satellites to fly in formation to measure the three-dimensional boundaries of the magnetosphere as it intersects with the solar wind gol conducts measurements of electrons and ions in the Earth's magnetotail the magnetosphere pushed back by the solar wind [Music] stereo-a and be observed the Sun with images and particle detectors and they fly off the Earth's Sun line providing a three-dimensional view of solar activity [Music] watch they use the moon to set themselves apart at the best possible distance to view the heliosphere [Music] you [Music] here we see the l1 fleet orbiting the Lagrange point number one between the Earth and the Sun l1 is the point between the Earth and the Sun where the gravitational pull is approximately equal in both directions spacecraft can orbit this location for continuous coverage of the Sun you might remember the Trojan asteroids of Earth Jupiter and Neptune that orbit the Lagrange points that we discussed earlier out here there is no magnetosphere so a good look at the solar wind is possible ace measures the composition and characteristics of the solar wind wind measures particle flows and fields in the solar wind Soho it's a famous satellite that studies the Sun from its deep core to the outer Corona and the solar wind it Ron I'll show you what it sees when a solar flare occurs you here we see the famous fleet satellites to study how magnetospheric instabilities produced the aurora borealis also known as sub storms you the heliopause fleet is Voyager 1 and Voyager 2 these spacecraft conducted the original planetary grand tour of the solar system in the 1970s and 1980s they have now traveled further than any human built spacecraft and are still returning measurements of the heliosphere [Music] remember one of the Sentinels of the heliosphere stereo - space-based observatories went ahead of the earth in its orbit the other trailing behind with this new pair of viewpoints scientists can see the structure and evolution of solar storms as they blast from the Sun and move out through space a coronal mass ejection with a broad front blasted from the Sun and headed towards Earth on November 26 through 28 2011 stereo caught the action the particle cloud the darker mass can be seen buffeting earth late in November 28 without the stereo instruments we would not be able to see the track of solar storms like this one these solar storms with their coronal mass ejections were responsible for the aurora borealis or northern lights and the Aurora Australis or Southern Lights here's a look at the aurora borealis and Aurora Australis taken from the space station the Aurora lights were a mystery for most of man's existence it wasn't until our modern understanding of the magnetosphere hiyya satellite observations in the second half of the 20th century was combined with quantum mechanics developed in the first half of the 20th century that a real understanding was reached [Music] what happens is that that magnetosphere routes the solar wind charge particles along the Earth's magnetic field lines to the north and south polar regions there they collide with oxygen and nitrogen atoms in the thermosphere quantum mechanics explains how these collisions create light I'll take a minute to explain this because it's relevant for understanding how a star's light can tell us how far away the star is thanks to the work of Niels Bohr a Danish physicist we discovered that electrons attached to atoms occupy quantized discrete energy levels call shells the further the shell is from the nucleus the greater the energy level and the larger the quantum number and thanks to Albert Einstein we discovered that light was also quantized as photons and that they were created when electrons dropped from higher to lower energy levels sometimes referred to as taking a quantum leap and absorbed when a photon collides with an atom and drives an electron to a higher energy level in the case of the Aurora the high velocity particles from the solar wind collide with the oxygen and nitrogen atoms in the thermosphere driving electrons in those atoms to higher energy levels when they drop back down photons are created for oxygen emissions we get mostly green light the most common roars from nitrogen emissions we get mostly blue or red these are rare in that there is less nitrogen that oxygen at the very top of the atmosphere will go deeper into quantum mechanics and light at the beginning of our segment on distant stars Voyager one no longer has a working plasma sensor so scientists needed a different way to measure the spacecraft's plasma environment to see if it was still in the heliopause or had moved into the bow shock area in interstellar space that's where the plasma density is expected to be 40 times greater than what we see inside the heliosphere but Voyager 1 can still measure the pitch of oscillations of the medium it is flying in in March 2012 a coronal mass ejection erupted from the Sun the solar storm that this zme created arrived at Voyager 1's location 13 months later in April 2013 voyager ones plasma wave instrument detected the movement here's the sound of the oscillations these particular oscillations meant that the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the heliopause so at 12 billion miles Voyager 1 was no longer in the heliosphere it was in interstellar space [Music] although the voyage craft will only transmit information to us for another decade or so they will continue to wander in a billion year journey to the Stars now that we have a feel for the size of the heliosphere let's review how far away the main objects in our solar system are the Sun is 93 million miles away and a million earths could fit inside it Jupiter the largest planet in the Solar System is 5.2 times further away from the Sun than the earth this puts its orbit at 480 million miles away from ours Pluto's orbit is three-and-a-half billion miles away we have seen the determination shock is 11 billion miles away and the bow shock is 12 billion miles away we'll cover how far away our nearest stellar neighborhood system Alpha Centauri is in our next segment on nearby stars [Music] in our first chapter on the earth we learned just how vast they are this how high the sky how far away the continents across the great oceans of the world but now that we've seen the enormous size of the solar system we can put Earth's size into this broader perspective back in 1990 Carl Sagan requested that Voyager 1 be turned around the photograph the earth it was only four billion miles away back then the picture highlights just how small the earth really is compared to the huge size of the solar system here is the famous clip he created around his photograph he expresses my feelings to a tee from this distant vantage point the earth might not seem of any particular interest but for us it's different consider again that dot that's here that's home that's us on it everyone you love everyone you know everyone you ever heard of every human being who ever was lived out their lives the aggregate our joy and suffering thousands of confident religions ideologies and economic doctrines every hunter and forager every hero and coward every creator and destroyer of civilization every King and peasant every young couple in love every mother and father hopeful child inventor and Explorer every teacher of morals every corrupt politician every superstar every Supreme Leader every saint and sinner in the history of our species lived there on the mote of dust suspended in a sunbeam the earth is a very small stage in a vast cosmic arena think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction of a dot think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner how frequent their misunderstandings how eager they are to kill one another how fervent their hatreds our posturings our imagined self-importance the delusion we have some privileged position in the universe are challenged by this point of pale light our planet is a lonely speck in the great enveloping cosmic dark in our obscurity in all this vastness there is no hint that help will come from elsewhere to save us from ourselves the earth is the only world known so far to harbor life there is nowhere else at least in the near future to which our species could migrate visit yes settle not yet like it or not for the moment the earth is where we make our stand it has been said that astronomy is a humbling and character-building experience there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world to me it underscores our responsibility to deal more kindly with one another and to preserve and cherish the pale blue dot the only home we've ever known [Music] you [Music]

Channel: David Butler

Views: 149,234

Rating: 4.9132009 out of 5

Keywords: howfarawayisit, \how far away is it\, \David Butler\, Heliosphere, \Termination Shock\, Heliopause, Heliosheath, \Bow Shock\, Voyager, Geotail, SOHO, Stereo, Magnetosphere, Borealis, Bohr, \quantum leap\, \Solar System\, Hubble, Spitzer, Chandra, ESO, telescope, Lagrange Point, STEM

Id: t3_VkTfCKv0

Length: 17min 42sec (1062 seconds)

Published: Fri Jan 24 2014

Reddit Comments

[u/babbles_mcdrinksalot]

Braveheart soundtrack is playing in the background, oddly enough.