Total eclipse

Never stare at the sun without proper eye protection.

An eclipse of the Sun can only occur at New Moon when the Moon passes between Earth and Sun at the correct distance. (The Moon’s orbit around the Earth is slightly elliptical).
The corona can only be safely viewed without the solar filter during the few brief minutes of totality -- that is, when the Moon blocks the entire face of the sun.
The rest of the time, you have to use the appropriate solar filter and never look directly at the Sun without proper eye protection.