Question

1. if objects cannot be seen from earth with optical telescopes, how are astronomers able to study them?

Explanation:

The problem is about studying celestial objects not visible with optical telescopes, which relates to astronomy (a subfield of Natural Science, specifically Physics or Astronomy - here Physics as a subfield of Natural Science is relevant). Astronomers use non - optical telescopes (like radio telescopes, X - ray telescopes, etc.) that detect other forms of electromagnetic radiation (radio waves, X - rays, gamma rays, etc.) emitted by these objects. Also, they use techniques like spectroscopy to analyze the light (or other radiation) from objects to determine their composition, temperature, etc., and astrometry to study their positions and motions.

Answer:

Astronomers use non - optical telescopes (e.g., radio, X - ray, gamma - ray telescopes) to detect other forms of electromagnetic radiation emitted by these objects. They also use techniques like spectroscopy (to analyze radiation for composition, temperature, etc.) and astrometry (to study positions/motions) to study such objects.