As we start our look at the solar system, where better to start than the sun? The sun is 150 million kilometres from earth (93 million miles). Light from the sun takes 8 minutes to reach the Earth, but since faster-than-light drive has not been invented (except in science fiction), it would take a lot longer to get there. But why would you go?
According to Wikipedia: It is a massive sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is the main source of energy for life on Earth. The Sun has been an object of veneration in many cultures and a central subject of astronomical research since antiquity.
There’s an old joke about Irishmen building a rocket to go to the sun, but they won’t burn because they’re going at night!
The clearest picture ever of a sunspot
If you want some statistics, here’s Wikipedia again: The distance between the Sun and the Earth was used to define a unit of length called the astronomical unit (au), now defined to be 149.5978707×106 kilometres. It is the largest and most massive object in the Solar System, its diameter is about 1,391,400 km (864,600 mi), around 109 times that of Earth’s. The Sun’s mass is around 330,000 times that of Earth’s, making up about 99.86% of the total mass of the Solar System. The mass of the Sun’s surface layer, its photosphere, consists mostly of hydrogen (~73%) and helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.
What began as a large molecular cloud collapsed to form the solar system, with the sun taking most of it and the remainder coalescing into the planets.
The Wikipedia article on the sun contains detailed information about the size and composition, and I recommend it if you want to go into the physics and chemistry of it.
The National Geographic website’s article on the sun is in simpler language. It says: The sun has extremely important influences on our planet: It drives weather, ocean currents, seasons, and climate, and makes plant life possible through photosynthesis. Without the sun’s heat and light, life on Earth would not exist.
The sun is largely made up of gases, and contains different layers. Interestingly, the layers don’t all revolve at the same rate and the complete sun revolves at between 25 and 35 days for one rotation. The equator revolves at a different speed to the poles. How does that work? In the core, nuclear fission occurs, converting hydrogen to helium and releasing a huge amount of energy as heat and light.
Ann Marie Thomas is the author of five medieval history books, a surprisingly cheerful poetry collection about her 2010 stroke and two further poetry collections, and the science fiction series Flight of the Kestrel, of which there are four books are out now. Follow her at http://eepurl.com/bbOsyz and get free books.