Astrophysics & Particle Physics-APPC 2026

Optical Astronomy is that area of observational astronomy concerned with the observation of celestial objects using visible light. It is a very old form of astronomy, and it uses telescopes and instruments to look at stars, galaxies, planets, nebulae, and other celestial events.Telescopes play a crucial role in optical astronomy because they enable astronomers to collect light and create detailed images. Ground-based optical telescopes are fitted with state-of-the-art optics and adaptive hardware to compensate for atmospheric distortion, whereas space-based telescopes, like the Hubble Space Telescope, avoid atmospheric disturbance altogether, delivering high-resolution images of distant objects.Photometry and spectroscopy are major methods in optical astronomy.

Photometry is used to measure the brightness of objects in the sky to analyze stellar variability, eclipsing binaries, and exoplanets, whereas spectroscopy examines the spectra of light to find chemical composition, temperature, radial velocities, and physical conditions in stars and galaxies.Optical astronomers also study star clusters, nebulae, galaxies, and planetary systems and trace their structure and evolution. High-resolution imaging allows for the identification of stellar birthplaces, supernova remnants, and active galactic nuclei, leading to a better knowledge of cosmic processes.Higher observational precision is achieved through advanced optical technology, such as charge-coupled devices (CCDs), adaptive optics, and interferometers. Multi-wavelength optical observations coupled with radio, infrared, ultraviolet, and X-ray telescopic data offer a complete picture of astronomical objects.Optical astronomy is instrumental in mapping the universe, stellar evolution, understanding galaxy evolution, and the detection of exoplanets.

It spans observational methods and theoretical astrophysics, enabling scientists to study light emitted or absorbed by stars and other objects in the universe, follow cosmic history, and make more sophisticated models of the structure and evolution of the universe.By observing the universe in visible light, optical astronomy keeps expanding humanity's understanding of the universe, providing information about both nearby planetary systems and far-away galaxies observable.