Humans, animals and plants on Earth need the sun because it provides most of the energy required to survive in this solar system. Earth would be a very cold and lifeless planet if it did not get its light and heat from the sun. Similarly, the Earth's stays in orbit because of the gravitational pull of the sun.Know More
Plants also need the sun's energy for the photosynthesis process used to manufacture food and oxygen. While a plant is an autotroph that make its own nutrients, animals and humans are heterotrophs that depend on autotrophs or other heterotrophs for food. Without food and oxygen animals and humans could not live on Earth.
Humans also need sunlight to manufacture vitamin D. This vitamin is necessary for the absorption of calcium that is important for strong bones and overall health.Learn more about Our Sun
Earth is the third planet in the solar system. Earth orbits the sun at a distance of roughly 93 million miles and is the only known planet capable of supporting life.Full Answer >
The star that shares the solar system with the Earth is the Sun. It is the star around which all the planets in the system revolve. According to About.com, the Sun weighs almost 99.86 percent of the total mass in the solar system.Full Answer >
Technically speaking, the sun is, in fact, not a source of inexhaustible energy, since every star eventually burns out. However, the sun's internal fuel supply will keep it burning for at least six billion years, enough to be considered inexhaustible for all practical purposes. The sun's nuclear furnace provides as much as 174 petawatts of solar energy to the planet, approximately 70 percent of which is absorbed by the surface.Full Answer >
Earth's solar system has only one sun, but if the word "sun" is taken to mean "any star with planets in orbit," the Milky Way might have as many as 400 billion suns. If the observed ratio of approximately one planet per star is consistent everywhere, the observable universe might contain 10^24, or 1 septillion, suns.Full Answer >