The Sun
The Sun is a yellow dwarf star (G2V), about 4.6 billion years old, and the dominant gravitational force in the Solar System. It has a diameter of roughly 1.4 million kilometers and contains around 99.8% of the Solar System’s mass. Nuclear fusion in its core converts hydrogen into helium, producing energy that warms the planets. Above the core lie the radiative and convective zones, followed by the visible photosphere (~5,500 °C), the chromosphere, and the much hotter corona (~2 million °C).
Source: science.nasa.gov
APODs including "The Sun"
A Total Solar Eclipse Reflected
05/08/2019
If you saw a total solar eclipse, would you do a double-take? One astrophotographer did just that -- but it took a lake and a bit of planning. Realizing that the eclipse would be low on the horizon, he looked for a suitable place along the thin swath of South America that would see, for a few minutes, the Moon completely block the Sun, both directly and in reflection. The day before totality, he visited an Argentine lake called La Cuesta Del Viento (The Slope of the Wind) and, despite its name, found so little wind that the lake looked like a mirror. Perfect. Returning the day of the eclipse, though, there was a strong breeze churning up the water -- enough to ruin the eclipse reflection shot. Despair. But wait! Strangely, about an hour before totality, the wind died down. This calmness may have been related to the eclipse itself, because eclipsed ground heats the air less and reduces the amount rising warm air -- which can dampen and even change the wind direction. The eclipse came, his tripod and camera were ready, and so was the lake. The featured image of this double-eclipse came from a single exposure lasting just one fifteenth of a second. Soon after totality, the winds returned and the water again became choppy. No matter -- this double-image of the 2019 July total solar eclipse had been captured forever.