Our Sun The centre of our solar system
Nicolaus Copernicus
Our Sun The sun represents 99.86% of the mass in our solar system. It is ¾ hydrogen and ¼ helium. More than 1 million Earths can fit inside the Sun. The surface area of the Sun is 11 990 times larger than the Earth s. The Sun s energy is created by nuclear fusion. This enormous quantity of energy is created when two hydrogen atoms fuse into a helium atom.
Our Sun The Sun travels at a speed on 220 km per second and it takes roughly 225-250 million years to complete an orbit of the Milky Way. The Sun is almost a perfect sphere. It takes 8 minutes for the light of the Sun to reach Earth. At 4.5 million years old, the Sun is about halfway through its life.
Formation of our Solar System Vidéo Our story starts about 4.6 billion years ago with a wispy cloud of stellar dust This cloud was part of a bigger nebula Part of the nebula was hit by a shockwave caused by a neighbouring exploding star and started to compress When it collapsed, it fell in on itself, creating a disk of material surrounding it.
Formation of our Solar System Finally the pressure caused by the material was so great that hydrogen atoms began to fuse into helium, releasing a tremendous amount of energy. Our Sun was born! Even though the Sun gobbled up more than 99% of all the stuff in its disk, there was still some material leftover.
Formation of our Solar System Bits of this material clumped together because of gravity. Big objects collided with bigger objects, forming still bigger objects. Finally some of these objects became big enough to be spheres these spheres became planets and dwarf planets Rocky planets, like Earth, formed near the Sun, because icy and gaseous material couldn t survive close to all that heat. Gas and icy stuff collected further away, creating the gas and ice giants. And like that, the solar system as we know it today was formed.
There are still leftover remains from the early days Asteroids in the asteroid belt are the bits and pieces of the early solar system that could never quite form a planet. Way off in the outer reaches of the solar system are comets. These icy bits haven t changed much at all since the solar system s formation.
Goldilocks Zone Planet Earth is in an ideal position from the Sun. We are far enough away so that it s not too hot. We are close enough so that it s not too cold. It is the perfect temperature for liquid water - Essential for life on our planet. Kepler-186f is another planet that resides in the habitable zone. Located about 500 light-years away in the Cygnus constellation.
Sunspots Sunspots are darker, cooler areas on the Sun s surface in the region called the photosphere. The photosphere has a temperature of 5,800 degrees Kelvin. Sunspots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them.
Sunspots Sunspots can be very large, up to 50,000 kilometers in diameter. They are caused by interactions with the Sun's magnetic field. It is somewhat like the cap on a soda bottle: shake it up, and you can generate a big eruption. Sunspots occur over regions of intense magnetic activity, and when that energy is released, solar flares and big storms called coronal mass ejections erupt from sunspots.
Solar Flare Video The magnetic field lines near sunspots often tangle, cross, and reorganize. This can cause a sudden explosion of energy called a solar flare. Solar flares release a lot of radiation into space. If a solar flare is very intense, the radiation it releases can interfere with our radio communications here on Earth. They can cause electricity shortages and power outages. Solar flares and CMEs are the most powerful explosions in our solar system.
Aurores Boréales Auroras are the result of collisions between gas particles in the Earth s atmosphere and charged particles coming from the Sun s atmosphere. The different colours are caused by the different gas particles in the sky (nitrogen, oxygen, carbon dioxide etc.) Vidéo 2
Radiation Radiation from the Sun, which is more popularly known as sunlight, is a mixture of electromagnetic waves ranging from infrared (IR) to ultraviolet rays (UV). It of course includes visible light, which is in between IR and UV in the electromagnetic spectrum.
Ozone Ozone is a molecule comprised of three oxygen atoms O3 and is abundant in Earth s upper atmosphere. Absorbs high-energy UV radiation from the Sun before it can hit the surface of the Earth.
There was a hole in the ozone layer
Comets A comet is a small, icy Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere around the comet and sometimes also a tail.
Comet 67P As seen from the Rosetta Spacecraft at a distance of 285 km.
Asteroids Asteroids are small, rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets. They are leftover remnant from the formation of the solar system 4.6 billion years ago There are lots of asteroids in our solar system. Most of them live in the main asteroid belt a region between the orbits of Mars and Jupiter.
Meteoroids A meteoroid is a piece of stony or metallic debris which travels in outer space Most meteoroids that enter the Earth's atmosphere are so small that they vaporize completely and never reach the planet's surface. If any part of a meteoroid survives the fall through the atmosphere and lands on Earth, it is called a meteorite.