The Sun: Practice Problem Solutions

1. About 109.

2. About 99.86%.

3. Fusion joins hydrogen nuclei into helium and releases energy. It happens in the core.

4. The photosphere.

5. Dark, cooler patches where strong magnetic fields break through the surface. The cycle is about 11 years.

6. A stream of charged particles from the Sun. When it hits Earth's magnetic field it makes auroras.

7. Sunlight can burn the retina in seconds without any pain, and homemade filters may let harmful light through. Use certified solar glasses (ISO 12312-2) or project the image.