An Astronomer is a scientist who studies the universe and its celestial bodies. STARGAZER is a 9 letter term for an Astronomer, which implies someone who looks up at the stars in wonderment. MOONSTRUCK is a 10 letter term for an Astronomer, which implies someone who is captivated by the moon's beauty. Nightwatchman is a 13 letter term for an Astronomer, which implies someone who watches the night sky vigilantly.