Celestial instruments are tools used to observe and measure astronomical objects and phenomena. They help astronomers study the positions, movements, and characteristics of celestial bodies like stars, planets, and galaxies. Common examples include telescopes, which magnify distant objects, and astrolabes, which help determine the altitude and azimuth of celestial bodies. These instruments have evolved over time, from simple devices like the armillary sphere to advanced technology such as space telescopes. Each instrument plays a crucial role in expanding our understanding of the universe and contributes to fields like astrophysics and navigation.