Outer Space for Kids: The Sun

The sun is a medium-sized dwarf star that sits at the center of our solar system. It's the closest star to our planet, and it is about 93 million miles away from us. The sun is about 4.5 billion years old, and it is about halfway through its life. The sun formed from a huge cloud called a nebula. The nebula was filled with hydrogen and helium gas, dust, and ice. The cloud's gravity was so strong that it pulled almost all of the matter into the center of it, and then the center got very hot. According to NASA, the center of the sun reaches 27 million degrees Fahrenheit!

Over time, other bits of material formed the planets, moons, asteroids, and comets. However, the sun contains the most matter of any object in the solar system. In fact, the sun contains 99.8% of all the matter in the solar system! As a result, the sun's gravity is so strong that it holds all of the other objects in our solar system in its orbit.

Sources: PBS, NASA

How does the sun make heat and light for us on Earth?

The sun is made of many layers of hydrogen gas. The core, or middle, of the sun is where the sun's energy is made. Gravity forces hydrogen atoms together, and once they are fused, they turn into helium atoms. This process is called nuclear fusion. It's not easy for the hydrogen atoms to fuse together because they are both positively charged and naturally want to repel each other. The gravity in the core of the sun is so strong that it creates a large amount of heat and pressure capable of squishing the atoms together. When the atoms fuse, they lose a little bit of mass, and that mass is converted into energy. That energy then travels to the surface of the sun, radiating heat and light throughout the solar system, and it takes about 8 minutes and 20 seconds for that light to get to Earth.

Sources: The Science Channel, National Geographic Kids, phys.org

Play NASA's fun fusion game, Helios!

In this pairing game, keep the Sun shining bright by matching up particles. The goal? To convert hydrogen atoms into helium atoms.

While the center of the sun reaches temperatures of around 27 million degrees, the surface of the sun is cooler. By the time energy reaches the surface, it cools to about 11,000 degrees Fahrenheit. Some areas of the sun's surface are even cooler -- about 7,000 degrees Fahrenheit. These areas appear darker on the surface and are called sunspots. 

Sometimes energy and matter on the surface of the sun erupt in a violent explosion called a solar flare. The energy from the solar flare reaches Earth in about eight minutes, but the matter can take hours or days to reach Earth. Solar flares can interrupt electronics and satellite functioning, but the matter usually cannot get through Earth's atmosphere.

Solar flares are sometimes accompanied by a coronal mass ejection (CME). CMEs are bubbles of radiation and particles of matter that explode at a high speed. CMEs cause a beautiful light show on Earth known as auroras. While fun to look at, CMEs can affect power grids on Earth.

CMEs, solar flares, and sunspots occur as part of the sun's 11-year solar activity cycle. The sun is surrounded by a magnetic field, and as the energy in and on the sun swirls around, these solar events take place. Learn more about sunspots, solar flares, and CMEs in World Book Student through the St. Louis County Library.  

Sources: World Book Student (image and information), NASA

Do you know why we have different seasons? Scientists believe that long ago Earth rotated on its axis straight up and down. Then one day, something really big named Theia slammed into Earth, making it tilt. Scientists also think that Theia's impact sent a bunch of rubble into space that eventually became our moon. Now, when Earth travels in its orbit around the sun, one end of the planet is closer to the sun while the other is farther away. Whichever hemisphere is tipped closer to the sun gets warmer. During June, July, and August, the northern hemisphere is tilted toward the sun, and during December, January, and February, the southern hemisphere is tilted toward the sun.

Sources: National Weather Service, NASA

When the moon passes directly between Earth and the sun, it covers part or all of the sun and the sky goes dark. This is called a solar eclipse. Total eclipses happen about every year and a half somewhere on Earth. Partial eclipses happen at least twice a year somewhere on Earth. Although eclipses are fun to learn about and watch, looking directly at the sun is very dangerous. To view an eclipse, you need to wear special glasses made especially for looking at the sun or make a pinhole projector or camera.

Learn how to make your very own pinhole camera from the NASA Jet Propulsion Laboratory at California Institute of Technology.

Source: NASA Space Place, NASA

Do you sneeze when you step into the sunshine? That's called a photic sneeze. It's not an allergy to the sun but rather a reflex that affects some people who have been in darker areas and then step into lighter areas. Scientists think between 10-35% of the population has photic sneezes, and there's a good chance that it is inherited through your genes. If you want to get fancy and impress your friends, you can tell them you have ACHOO: Autosomal Dominant Compelling Helio-Ophthalmic Outburst Syndrome!

Source: PBS