This Furniture Grows On Trees

1234567
Across
  1. 3. - the distance traversed by light in one mean solar year, about 5.88 trillion mi. (9.46 trillion km): used as a unit in measuring stellar distances
  2. 5. - the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.
  3. 7. - a body of coherent matter, usually of indefinite shape and often of considerable size
Down
  1. 1. - of, pertaining to, or resembling a planet or the planets.
  2. 2. - any surface that is flat and round,
  3. 4. - an expert in astronomy; a scientific observer of the celestial bodies.
  4. 6. - the luminance of a body, apart from its hue or saturation, that an observer uses to determine the comparative luminance of another body. Pure white has the maximum brightness, and pure black the minimum brightness.