MISSION EXPLORING THE SUN Have you ever played outside on a summer day You likely felt the sun's warm rays on your skin The sun is the biggest brightest object in our galaxy It brings heat light and energy to Earth Without the sun there would be no life here Our planet would be too cold and icy Super Star The sun is actually a star It's the closest star to Earth in the universe But it is still very far away Imagine there is a highway leading straight to the sun It would take more than 163 years to drive there Earth's next closest star is 250 000 times farther away than the sun Milky Way Marvel Most stars are part of large clusters called galaxies And there are billions of galaxies in the universe The sun
Earth's atmosphere bends light So we can still see the sun after it has disappeared over the horizon belongs to the Milky Way galaxy The sun spins on its axis as it orbits the center of the Milky Way Stuck in the Middle The sun is at the center of our solar system This giant ball of light makes up more than 99 8 percent of our solar system's mass It is about 109 times larger than Earth
CHAPTER 1 FROM BEGINNING TO END To watch the sun's birth you would need to travel more than 4 5 billion years back in time That is when our solar system formed The sun began as a huge cloud of gas and dust particles Energy waves pressed the particles together Gravity made them spin and collapse inward As the cloud compressed further it spun faster Over time it became a flat pancake like disk Leftover chunks of gas and dust orbited the disk These eventually became our solar system's eight planets Most of the disk's mass clumped at its core Its temperature became hotter and hotter Finally a protostar formed Over the next 50 million years this protostar's core continued to collapse It also became much hotter Eventually it grew into the star we call the sun
This stellar nursery or nebula contains more than 300 newborn stars The force of gravity is very strong in the sun's core It fuses hydrogen atoms together creating helium This process called nuclear fusion makes a lot of energy
