Time to solve some puzzles

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Across
  1. 4. The periodic change in the sea level due to the moon and the sun
  2. 5. A system where astronomers quantify measurement of stars
  3. 6. The science of plants
  4. 7. The science that deals with climate and weather
Down
  1. 1. The science that deals with nature
  2. 2. The science that deals with universe beyond the earth
  3. 3. The science of life and living matter