The crossword solution for the term FERTILE PLAIN is VEGA, which is a four letter word. Vega is a star in the constellation Lyra and the fifth brightest star in the night sky. It is also known as Alpha Lyrae and is one of the most luminous stars in the Milky Way. Vega is a blue-white star that is about 25 light years away from Earth. It is a very important star in astronomy and is often used as a reference point for measuring stellar distances.