The Sun - basics

 

1. Composition: The Sun is mainly composed of hydrogen (about 74% by mass) and helium (about 24% by mass). more
2. 
   
3. The remaining 2% consists of trace amounts of other elements. more
4. 
   
5. Size and Mass: The Sun is enormous, with a diameter of about 1.4 million kilometers (870,000 miles), which is about 109 times the diameter of Earth. 
6. 
   
7. It has a mass of approximately 1.989 × 10^30 kilograms, which is about 333,000 times the mass of Earth.
8. 
   
9. Energy Source: The Sun generates energy through a process called nuclear fusion.
10. 
    
11. In its core or centre, hydrogen atoms fuse together to form helium, releasing vast amounts of energy in the process. 
12. 
    
13. This process is responsible for the Sun's heat and light.
14. 
    
15. Surface Features: The Sun's surface, known as the photosphere, is a dynamic and active region. 
16. 
    
17. The word photosphere means "light sphere" – which is apt because this is the layer that emits the most visible light. It's what we see from Earth with our eyes. source
18. 
    
19. It has dark spots called sunspots more , which are cooler and less active areas caused by magnetic activity. more
20. 
    
21. Solar flares and coronal mass ejections (CMEs) are also common, which are powerful eruptions of energy and particles into space.
22. 
    
23. Solar Atmosphere: Surrounding the photosphere is the Sun's atmosphere, consisting of several layers. The outermost layer is the corona, which is visible during a total solar eclipse as a faint, pearly-white halo. more  images lower down on the page
24. 
    
25. The corona has extremely high temperatures and emits solar wind  more , a stream of charged particles that affects space weather.
26. 
    
27. In physics, a charged particle is a particle with an electric charge.  source
28. 
    
29. Importance to Earth: The Sun plays a crucial role in sustaining life on Earth. 
30. 
    
31. It provides light and heat, enabling photosynthesis in plants and driving the planet's weather systems. 
32. 
    
33. It also affects Earth's climate and seasons.
34. 
    
35. Age and Lifespan: The Sun is estimated to be about 4.6 billion years old and is roughly halfway through its expected lifespan. How long do we have?
36. 
    
37. It is expected to continue fusing hydrogen and producing energy for another 5 billion years before it exhausts its fuel and eventually transitions into a red giant.