text: Deflection of starlight was observed by William Wallace Campbell while he was observing one of these events at the Lick Observatory.
full_question: Deflection of starlight was observed by William Wallace Campbell while he was observing one of these events at the Lick Observatory. Walter Grotrian and Bengt Edlen found that the green emission line found as a result of these events was not actually a new element, but was instead highly ionized iron. Arthur Eddington experimentally confirmed Einstein's theory of general relativity using one of these events in 1919. While working in Madras, Pierre (*) Hansen used one of these events to discover the element Helium. The "annular" type of this event occurs when a disk surrounds the occuluding body. For 10 points, name these events during which the corona becomes visible because the moon is in front of the sun.
first_sentence: Deflection of starlight was observed by William Wallace Campbell while he was observing one of these events at the Lick Observatory.
raw_answer: solar eclipse [prompt on eclipses until "sun" is read and accept it afterwards] 