These are the proceedings of the Symposium 3 of JENAM 2011 on new scientific challenges posed by the Sun. The topics covered are  

1. The unusual sunspot minimum, which poses challenges to the solar dynamo theory

2. The Sun’s Terra-Hertz emission, which opens a new observational window

3. Corona wave activity

4. Space weather agents - initiation, propagation, and forecasting

In 21 in-depth contributions, the reader will be presented with the latest findings.