A professional who observes and interprets celestial phenomena and relates research to basic scientific knowledge or to practical problems, such as navigation. Responsibilities include:

• Studies celestial phenomena by means of optical, radio, or other telescopes, equipped with such devices as cameras, spectrometers, radiometers, photometers, and micrometers, which may either be on ground or carried above atmosphere with balloons, rockets, satellites, or space probes.
• Interprets information obtained in terms of basic physical laws.
• Determines sizes, shapes, brightness, spectra, and motions, and computes positions of sun, moon, planets, stars, nebulae, and galaxies.
• Calculates orbits of various celestial bodies.
• Determines exact time by celestial observations, and conducts research into relationships between time and space.
• Develops mathematical tables giving positions of sun, moon, planets, and stars at given times for use by air and sea navigators.
• Conducts research on statistical theory of motions of celestial bodies.
• Analyzes wave lengths of radiation from celestial bodies, as observed in all ranges of spectrum.
• Studies history, structure, extent, and evolution of stars, stellar systems, and universe.
• May design new and improved optical, mechanical, and electronics instruments for astronomical research.
• May specialize in either observational or theoretical aspects of stellar astronomy, stellar astrophysics, interstellar medium, galactic structure, extragalactic astronomy, or cosmology.