Scientists believe that the sun formed several thousand other stars within the cluster. The Sun is 865,000 miles in diameter and the right size to burn consistently for a very long time, like 8 billion years. The solar system lies about 26,000 light-years from the center of our galaxy, the Milky Way, or around two-thirds the way. The story of these vast planets coming orbiting an average yellow star is 6 billion years long.
In 1543, Nicolaus Copernicus finally published his work proposing a Sun-centered model. Unfortunately, Copernicus’s model was top-heavy and hard to predict planetary motions. Astronomer Johannes Kepler made a brilliant mental leap: Based on observations by his mentor Tycho Brahe.
Kepler realized the planets moved around the Sun in ellipses, not circles, as Copernicus had assumed. This fixed everything, including those aggravating planetary motions. Solar comes from the word “sol,” for Sun. Many more asteroids are scattered around the solar system, but most are in the central belt.
How sun was born?
The Sun was born through stellar formation within a vast cloud of gas and dust known as a molecular cloud. Here’s a general overview of how the Sun and other stars are believed to have formed:
Molecular Cloud Collapse: Stellar formation begins with the gravitational collapse of a dense region within a molecular cloud. This collapse can be triggered by various factors, such as the shockwave from a nearby supernova or the compression caused by the collision of two molecular clouds.
Protostar Formation: As the dense region collapses, it forms a rotating disk of gas and dust, known as an accretion disk, around a central core. The core, known as a protostar, continues to accrete mass from the surrounding material. Gravitational forces pull the gas and dust inward, causing the protostar to heat up and become denser.
Nuclear Fusion Ignition: As the protostar continues to accrete mass, the temperature, and pressure at its core increase. When the temperature reaches about 15 million degrees Celsius, nuclear fusion of hydrogen begins. This fusion process releases an immense amount of energy and marks the birth of a star.
Main Sequence Star: Once nuclear fusion ignites, the protostar enters the main sequence phase, generating energy by converting hydrogen into helium through nuclear fusion. This energy release counterbalances the gravitational forces, leading to a stable equilibrium state. The Sun is currently in this phase, fusing hydrogen into helium in its core.
Lifetime and Evolution: The Sun and other stars remain in the main sequence phase for most of their lives. A star’s time in this phase depends on its mass. More massive stars burn through their nuclear fuel more rapidly and have shorter main sequence lifetimes.
End Stages: Eventually, the Sun will exhaust its hydrogen fuel in the core. The core will contract as the hydrogen runs out, and the outer layers will expand, turning the Sun into a red giant. This phase will mark the later stages of the Sun’s life, leading to the ejection of its outer layers and the formation of a white dwarf remnant.
About 4.5 billion years ago, gravity built a cloud of dust and gas together, which might have come from the explosion of a nearby star called a supernova. This massive concentration of intestinal gas and dust created a molecular cloud it would form the sun’s birthplace. The cloud began to collapse under its gravity for cold temperatures, forming young stellar objects known as protostars. As Dravid repelled the gas and earth together, a cloud collapsed, forming a sole nebula.
As it collapsed, the cloud began to spin. Eventually, the cloud is hotter in the center, with a disc of gas and dust surrounding it. It was new at the edges. As the disk got, thinner and thinner particles began to stick together and form clumps. Some of them got bigger, eventually forming planets and moons.
So near the cloud center, only rocky material could stand the great heat like Mercury, Venus, Earth, and Mars. Around the new Sun was still a spinning disk of gas and dust. Over time it cooled and came together due to magnetism and gravity. Metals and rocks began forming close to the Sun, but it was still too hot for other materials to become solid.
Fast forward 100 million years, and it had grown into a giant ball sweeping up billions of tons of celestial. It is where the earth came from. About 93 million miles away, at the heart of the giant nebula, the pressure and temperature of a ball of hydrogen gas had become so great that the atoms were beginning to fuse. Every nebula is different. The clouds contain nitrogen, oxygen, iron, silica, and all the other stuff needed to build a planet.
Then the tireless force of gravity started to pull it back together, and the heavy engineering that produced planets began. As a cloud continued to fall in, the center eventually got so hot that it became a star. Today we call it the Sun. The new star below all the gas and dust of the new solar system with a solid stellar weight. Scientists have found that the solar system is about 4.6 million years old by stirring meteorites left over from this early phase of the solar system.
As the Sun ignited, it produced a massive blast of solar wind and a radioactive gust of energy. It blew all the remaining dust and gas out to the solar system’s edge.
Size and Distance:
- About 93 million miles from Earth.
- The Sun’s volume is 1.3 million bigger than Earth’s.
- The Sun’s radius is 432,168.6 miles (695,508 kilometers).
Speed & Orbit:
- The average velocity of the Sun is 450,000 miles per hour (720,000 kilometers per hour). It takes about 230 million years to make one complete orbit around the Milky Way.
- The axial tilt of the Sun is 7.25 degrees to the plane of the planets’ orbits.
The Sun spins around 25 days at the equator but rotates once on its axis every 36 Earth days at the poles.
- Like other stars, Sun is a ball of gas.
- It is made of 91.0% hydrogen and 8.9% helium. By mass, it is about 70.6% hydrogen and 27.4% helium.
The Sun has six regions: Radiative zone, Core, Convective zone in the interior, Visible surface (photosphere), Chromosphere, and Corona.
- At the core, the temperature is about 27 million degrees Fahrenheit or 15 million degrees Celsius.
- The surface of the Sun is about 10,000 degrees Fahrenheit (5,500 degrees Celsius).
Sun energy formation (Nuclear fusion)
At the core, the Sun gives birth to light forged, one of the most violent nuclear fusion reactions in the universe. The specific nuclear reaction that powers the Sun is fusion. It is a process of converting hydrogen into helium. Two hydrogen atoms make a helium atom. It’s hard to get two atoms to fuse two protons.
They have the same charge, and both are positively charged. So they want to repel each other. For the fusion reaction, protons must come together with vast energy or velocity to get close enough. That’s very rare to force protons together. That takes immense amounts of heat and pressure generated by the invisible hand of gravity.
The Sun contains 99.08 percent of all the matter in the solar system. That’s a lot of mass, which pulls the Sun together with unimaginable gravitational force. Both gravities crush things down, things get close enough together, and nuclear fusion happens. Hydrogen atoms slammed together 100 million quadrillion times each second in this nuclear compactor.
Some of these collisions are so powerful that atoms fuse, releasing energy. When the protons come together to bind, they lose a little mass converted into energy. About 5 million tons of stuff are converted to energy every second of every day.
Sun axis & Sunspots
In 1612, Galileo Galilei observed sunspots moving across the sun discovery of the time. Sunspots occur when the sun’s plasma interacts with its magnetic field, leading to solar flares and other types of solar storms. So the Sun rotates but doesn’t spin at the same rate because it’s gas. The Sun isn’t a solid object like a planet. The Sun rotates fastest at its equator. On the sun’s equator, any point takes 24 days to rotate completely around the star, while the poles take more than 30 days.
These measurements have been made using sunspots as surface tracers and watching them turn with a star. Astronomers usually work with a rotation rate of an area about 26 degrees above or below the equator. It is where most sunspots are observed. One complete rotation takes over 27 days at this latitude, known as a Carrington rotation. The inner parts of the Sun also spend faster than the outer layers.
Solar system formation
The sun’s birth is essential for the solar system because it is the primary energy source. How was the solar system formed? When this giant cloud collapsed, it had some angular momentum. So not all the matter collapsed into the central star-forming region. The material also began to orbit around the protosun forming a protoplanetary disk roughly 200 au in diameter. It is in this disk that the planets started to form.
The disk was composed of gas and dust. Cosmic dust comprises tiny rock particles less than a micron in size. These grains began to stick together and grew in size until they formed one-kilometer-wide objects known as planetesimals. They were gravitationally attracting each other. As a result, they continued to grow in size through a process known as accretion.
- It’s thought that the inner solar system at this point contained 50 to 100 moon to mars size objects known as planetary Embryos.
Further from the Sun, water and other ice could form more relaxed. They came together to make larger pieces called planetesimals, making giant planets. These planets had enough gravity to capture the surrounding gas and became Jupiter and Saturn’s gas giants. Some scientists think Jupiter formed first and was pulled towards the Sun by the swirling material in the inner disk.
When Saturn started, it moved inwards too. The planets got closer and swept up the gas between them. They then began to journey outwards together. Jupiter’s large size stopped rocky material from clumping together. The asteroid belt is full of these rocky scraps of the Solar System.
When Jupiter moved inwards, it fed on lots of material, so Mars had less to form later. In the inner Solar System, chunks of metal and rock slowly created the rocky planets. Within 100 million years, early planets were orbiting the Sun with lots of leftover material.
The young Sun had a phase of releasing strong winds. It blew the extra gas outwards, stopping the rocky planets and early gas giants from growing. The outwards moving gas was pulled around the snowball cores of Uranus and Neptune’s ice giants in the outer Solar System.
Many of the leftover ice balls flew out into the spherical Oort cloud. They occasionally got flung inwards, becoming comets, and collided with the rocky planets. Perhaps comets brought ice and gases back to these planets providing material for their atmospheres and bringing water to the Earth. For the first billion years, any stray pieces of rock and ice would have been flying around, creating many collisions.
The Earth’s Moon could result from a large object impacting the Earth. Similar impacts may have reversed Venus’ spin and knocked Uranus onto its side. The giant planets captured some of the planetesimals still floating around to form Moons around them. Scientists are looking at distant stars with exo-planets to see how they form. Based on observations of other stars, astronomers predict Sun will die in another 10 billion years.
Pitjeva, E. V.; Standish. “Proposals for the masses of the three largest asteroids, the Moon–Earth mass ratio and the Astronomical Unit.”
Williams, D.R. “Sun Fact Sheet.” NASA Goddard Space Flight Center.
Zombeck, Martin. Handbook of Space Astronomy and Astrophysics 2nd edition. Cambridge University Press.
Asplund, M.; Grevesse, N.; Sauval. “The new solar abundances – Part I: the observations.” Communications in Asteroseismology.
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