Answer:
Emmett Till's murder was such a spark in the civil rights movement because there was proof that Emmett was not guilty of what the people accused him of, he was only 14 years old at the time of his death and because the people that killed him admitted in a national newspaper that they killed him and were still found not guilty.
The success of Portugal's exploration of Africa affected Spain in that it put Portugal in a position of economic dominance, which forced Spain to up its efforts to obtain new resources from the Americas.