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If there was a way to re-fuel a commercial airliner in flight it would take one about 45 hours to fly around Earth at the equator.
It would take the same airliner about 6.3 months to fly around the Sun. The Sun is extremely close to being a perfect sphere and is not anywhere near as oblate as Earth so it wouldn't matter if you didn't fly around the Sun's equator.
As photographers we know the Sun's surface temperature (color - for white balance purposes) is about 5800° K .
The temperature of the Sun's core is some 15,700,000° K.
Each second the Sun 'burns' (actually fuses via the proton-proton chain) some 620 metric tons of hydrogen, into some 616 metric tons of helium 'ash', which produces some 4.3 metric tons of radiation (E=mc²) that is mostly light (photons).
However that 'mostly light (photons)' is pretty much all x-rays (0.01 to 10 nanometers). The x-rays work their way from the core to the surface of the Sun (a process that takes several million years) they diffuse and cool and at the surface are then some 50% infrared photons (light), 40% visible photons (light - 400 to 700 nanometers), and 10% UV photons (light).
The Sun's core is 20% to 25% of the Sun’s size. Core density is some 150 times the density of water.
They recently determined the core rotates once every 4 days or so.
Viewed from Earth's equator (synodic) the apparent rotational period of the Sun at its equator is about 26.25 days, about 35 days at the Sun's poles. Relative to the stars (sidereal) the rotational period of the Sun at its equator is 24.5 days and 33.5 days at the poles.
99% of the Sun's power is generated within 24% of the Sun's radius, and by 30% of the radius, nuclear fusion has essentially stopped.
In 5.5 billion years the Sun will be twice as luminous as it is now and will be at the end of that part of it's life it has spent as a Main Sequence star.
Over the next 500,000,000 years the Sun will double in size as it burns hydrogen in a shell around an inert helium core.
It will then expand more rapidly over the next half a billion years until it is over 200x larger than today and a couple of thousand times more luminous.
The Sun will then spend about 1 billion years as a red giant and will spew about 1/3 of it's mass away in a powerful solar wind. As a red giant the Sun's surface temperature will have dropped to about 3500° K.
When the red-giant phase ends the Sun has approximately 120 million years of active life left, but some pretty spectacular stuff is going to happen over the 120 million years.
First, that inert core of helium gets hot enough (6x hotter than the sun's core is now) to ignite violently in what is called a helium flash (triple-alpha process), where it is estimated that 6% of the core (itself 40% of the Sun's mass) will be converted into carbon within a matter of minutes.
Because of the helium flash the Sun will shrink from 200x larger to around 10x its current size and 50 times the luminosity. It's surface will heat back up to a surface temperature a little lower than today.
The sun will become moderately larger and more luminous over about 100 million years as it continues to burn helium in the core.
When the helium in the core is exhausted, the Sun will repeat the expansion it did when the hydrogen in the core was exhausted, except that this time it all happens faster. Once again the Sun becomes larger and more luminous.
The Sun will then be alternately burning hydrogen in a shell or helium in a deeper shell around the new carbon core made during the helium flash. The carbon is inert, not hot enough to fuse.
After about 20 million years the Sun becomes increasingly unstable, with rapid mass loss and thermal pulses that increase the size and luminosity of the Sun for a few hundred years every 100,000 years or so.
The thermal pulses become larger each time, with the later pulses pushing the luminosity to as much as 5,000 times the current level and the radius to over 1 AU (1 AU is the radius of Earth's orbit).
The process speeds up again and the Sun begins rapidly ejecting mass.
The luminosity stays approximately constant as the temperature increases, with the ejected half of the Sun's mass becoming ionized into a planetary nebula as the now exposed core reaches 30,000 K. The core no longer has any active nuclear processes and is pretty much just carbon.
The final naked core, called a white dwarf, will have a surface temperature of over 100,000 K, and contain an estimated 54.05% of the Sun's present day mass.
The planetary nebula will be visible for some 10,000 years before it disperses, but the white dwarf core will survive for trillions of years before fading to a hypothetical black dwarf.
Note: the oldest any star can be is some 13.3 billion years, so no star is anywhere old enough to have become a black dwarf.
Somewhat more than 97% of all the stars in the universe will become white dwarfs.
It would take the same airliner about 6.3 months to fly around the Sun. The Sun is extremely close to being a perfect sphere and is not anywhere near as oblate as Earth so it wouldn't matter if you didn't fly around the Sun's equator.
As photographers we know the Sun's surface temperature (color - for white balance purposes) is about 5800° K .
The temperature of the Sun's core is some 15,700,000° K.
Each second the Sun 'burns' (actually fuses via the proton-proton chain) some 620 metric tons of hydrogen, into some 616 metric tons of helium 'ash', which produces some 4.3 metric tons of radiation (E=mc²) that is mostly light (photons).
However that 'mostly light (photons)' is pretty much all x-rays (0.01 to 10 nanometers). The x-rays work their way from the core to the surface of the Sun (a process that takes several million years) they diffuse and cool and at the surface are then some 50% infrared photons (light), 40% visible photons (light - 400 to 700 nanometers), and 10% UV photons (light).
The Sun's core is 20% to 25% of the Sun’s size. Core density is some 150 times the density of water.
They recently determined the core rotates once every 4 days or so.
Viewed from Earth's equator (synodic) the apparent rotational period of the Sun at its equator is about 26.25 days, about 35 days at the Sun's poles. Relative to the stars (sidereal) the rotational period of the Sun at its equator is 24.5 days and 33.5 days at the poles.
99% of the Sun's power is generated within 24% of the Sun's radius, and by 30% of the radius, nuclear fusion has essentially stopped.
In 5.5 billion years the Sun will be twice as luminous as it is now and will be at the end of that part of it's life it has spent as a Main Sequence star.
Over the next 500,000,000 years the Sun will double in size as it burns hydrogen in a shell around an inert helium core.
It will then expand more rapidly over the next half a billion years until it is over 200x larger than today and a couple of thousand times more luminous.
The Sun will then spend about 1 billion years as a red giant and will spew about 1/3 of it's mass away in a powerful solar wind. As a red giant the Sun's surface temperature will have dropped to about 3500° K.
When the red-giant phase ends the Sun has approximately 120 million years of active life left, but some pretty spectacular stuff is going to happen over the 120 million years.
First, that inert core of helium gets hot enough (6x hotter than the sun's core is now) to ignite violently in what is called a helium flash (triple-alpha process), where it is estimated that 6% of the core (itself 40% of the Sun's mass) will be converted into carbon within a matter of minutes.
Because of the helium flash the Sun will shrink from 200x larger to around 10x its current size and 50 times the luminosity. It's surface will heat back up to a surface temperature a little lower than today.
The sun will become moderately larger and more luminous over about 100 million years as it continues to burn helium in the core.
When the helium in the core is exhausted, the Sun will repeat the expansion it did when the hydrogen in the core was exhausted, except that this time it all happens faster. Once again the Sun becomes larger and more luminous.
The Sun will then be alternately burning hydrogen in a shell or helium in a deeper shell around the new carbon core made during the helium flash. The carbon is inert, not hot enough to fuse.
After about 20 million years the Sun becomes increasingly unstable, with rapid mass loss and thermal pulses that increase the size and luminosity of the Sun for a few hundred years every 100,000 years or so.
The thermal pulses become larger each time, with the later pulses pushing the luminosity to as much as 5,000 times the current level and the radius to over 1 AU (1 AU is the radius of Earth's orbit).
The process speeds up again and the Sun begins rapidly ejecting mass.
The luminosity stays approximately constant as the temperature increases, with the ejected half of the Sun's mass becoming ionized into a planetary nebula as the now exposed core reaches 30,000 K. The core no longer has any active nuclear processes and is pretty much just carbon.
The final naked core, called a white dwarf, will have a surface temperature of over 100,000 K, and contain an estimated 54.05% of the Sun's present day mass.
The planetary nebula will be visible for some 10,000 years before it disperses, but the white dwarf core will survive for trillions of years before fading to a hypothetical black dwarf.
Note: the oldest any star can be is some 13.3 billion years, so no star is anywhere old enough to have become a black dwarf.
Somewhat more than 97% of all the stars in the universe will become white dwarfs.
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