My nationality is polish and my job occupation is astronomer. i was one of the first to successfully challenge the geocentric model of the universe with my book, 'on revolutions of the celestial spheres'. who am i?

Using complete sentences, compare and contrast the leadership and accomplishments of martin luther king, jr. and frederick douglass.

When conducting research for forming a hypothesis, which practice should historians follow?

During the 1920s, the federal reserve increased the money supply and kept interest rates very low, encouraging consumer spending and the brisk borrowing of money. business investment and the expansion of businesses grew rapidly during the 1920 to meet the needs of this huge consumer spending. however, during the crash of 1929, the federal reserve reversed its expansionary monetary policy and cut off the money supply by almost 30%, causing banks to not have enough currency on hand when depositors wanted their hard-earned money. after reading the prompt, what can you surmise happened next that contributed to the great depression? a) black tuesday b) collapse of banks c) high unemployment d) election of franklin d. roosevelt