1. The Sun

2. About three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. The Sun, like most stars, is a main sequence star, and thus generates its energy by nuclear fusion of hydrogen nuclei into helium

3. Fusion vs. Fission

4. Prominence A prominence is a large, bright feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's corona.

5. Prominence A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months.

6. Prominence A typical prominence extends over many thousands of kilometers. The largest on record was observed by the Solar and Heliospheric Observatory (SOHO) in 1997 and was some 216,000 miles long – roughly half the radius of the Sun or 28 times the diameter of the Earth.

7. Solar Prominence

11. Solar Flare A solar flare is a large explosion in the Sun's atmosphere that can release massive amounts of energy (about a sixth of the total energy output of the Sun each second).

12. Solar Flare

15. Solar Wind The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. Phenomena related to the solar wind include geomagnetic storms that can knock out power grids on Earth, the aurorae (northern and southern lights), and the plasma tails of comets that always point away from the Sun.

16. Solar Wind

17. Aurora Borealis (Northern Lights) An aurora is a natural light display in the sky, particularly in the polar regions, caused by the collision of charged particles directed by the Earth's magnetic field.

18. The Northern Lights

19. Aurora Borealis (Northern Lights) An aurora is usually observed at night. The aurora borealis most often occurs near the equinoxes.

20. The Northern Lights

23. Explaining the Northern Lights