The unimaginablely powerful raging heart of our Solar System the Sun, is responsible for and maintains all life on earth, it is like an engine that drives our weather and climate, and plant life cannot photosynthesize without it. All power we use can be traced back to energy from the Sun, from turning on a light, to pressing the accelerator on your car, to powering the screen you are looking at now.
Our star in the Galaxy at around 4.5 billion years old, and 93 million miles away. It converts more than 4 million tonnes of matter in it’s core into energy every second, but it has enough to keep going for another 5 billion years. The volume of it’s interior could hold 1.3 million Earths, and 109 earths would be needed to fit across it’s disk. It contains 99.86 % of all the mass in our Solar System. In 1 second the Sun puts out more energy than has been used in all of human history, yet just half a billionth of that energy actually reaches the Earth.
A photon of light produced in the core can take hundreds of thousands to a million years, just to get to the Sun’s surface and then travel the 8 minutes to Earth. This is because the centre of the Sun is extremely dense and photons collide and bounce off each other constantly. It’s a very long journey from the core to the surface and this takes a huge amount of time, so the sunlight that warms your face is actually ancient, probably produced well before the last ice age.
The Sun was likely formed from the result of a supernova blast over 4.5 billion years ago. An ageing massive star’s nuclear fusion eventually shuts down causing the star to implode on itself before exploding with a cataclysmic blast that can even outshine the entire Galaxy. The shockwaves from the supernova radiate outwards, slamming into interstellar clouds and compressing their dust and gas to create new stars. The Sun was one of these new stars. It’s a never ending process of death and rebirth, seeding our Galaxy and others with suns and planets. The Sun is a heavy element rich star, and the solar system is also rich in heavy elements like gold and uranium. This suggests the supernova formation as these cannot be created any other way.
Everything…trees, oceans, rocks, car, bridges, even ourselves originally came from the interior of an earlier generation star in a supernova explosion. A vast cloud of gas and dust that somehow manages to come together to form planets, life, and intelligence.
The Sun has a very strong magnetic field and it’s also huge, going way past Pluto. The Sun rotates once every 27 days, and this has the effect of twisting the magnetic field around itself. Unlike the Earth which has a magnetic north and south pole, the Sun has 1 to 10 million bits of north and bits of south pole all over the surface. So this chaotic rotating, mass of different magnetic polarities gets twisted and contorted, producing complicated structures and loops thousands of kilometres over the surface. These magnetic loops are so big that the planet Jupiter could easily fit underneath them.
These magnetic contortions carry and channel plasma at temperatures of millions of degrees. When magnetic field lines tangle, twist and wrap around each other, the stress can be too great and they break apart releasing tremendous bursts of energy in the form of coronal mass ejections or solar flares. The stress is built up in the magnetic fields just like you would wind up a rubber band very tightly, then release it. These massive bursts of super hot plasma can even be seen unwinding and twisting as they race out from the Sun. One of these solar flares releases up to a billion mega tonnes of energy, equivalent to a million volcanic eruptions on Earth. A coronal mass ejection can even be so violent that a solar tsunami can result, waves of million degree plasma higher than the Earth race out from the explosion on the Sun’s surface at speeds of 560,000 miles per hour.
A lot of material is thrown out into space from the explosion in the Sun’s corona as the solar flare travels out into space at speeds of 2,400 kilometres per second, fast enough to cross the United States in 2 seconds. At this speed a solar flare can reach the Earth in a matter of hours, knocking out satellites and disrupting communications.
The Sun has darker areas on it’s surface called sunspots, these are areas where the magnetic fields are strongest, so strong that normal convection is reduced causing cooler areas. They show up as dark spots on photographs but are only dark compared to the surrounding Sun’s surface, if you could take one of the Sun an suspend it in space it would be 10 times brighter than the full Moon. Sunspots vary over an 11 year cycle called the solar cycle.
Our Sun is roughly 4.5 billion years old and will last till it’s about 10 billion years old, so it’s half way through it’s lifetime. The Sun doesn’t have enough mass to explode in a supernova but will instead become a red giant star in about 5 billion years. Up to that point the Sun will get brighter and brighter, at a rate of 10 % every billion years. Eventually the hydrogen fuel in the core will run out and cause the outer layers to expand to 250 times the present radius, while the core contracts and heats up even further. This new red giant star in the Galaxy will engulf the Earth in the process as it’s expansion will cover our orbit, boiling our seas and atmosphere away into space and wiping out all life. In the end the Sun will eventually throw off it’s outer layers into space, creating a planetary nebula and leaving behind an extremely hot stellar core in the middle. This core will cool and fade over billions of years to become a white dwarf star. Planetary nebulae are some of the most amazing and intricate astronomical objects, such as the Eskimo Nebula, the Cat’s Eye Nebula, and the Butterfly Nebula.