Astronomy is a space science that has been in existence since antiquity, with its origin strongly tied with starkly varied subjects such as religion, mythology, astrology and mathematics. Dating back to the early civilizations of the Harappans, Mayans and ancient Chinese, astronomy was used for navigation, keeping track of time and orient the construction of their cities.
Studying the heavens above was primarily done through periodic observations of the night sky, recording and interpreting them. In the 17th century, Galileo Galilei became the first person to observe celestial objects using a telescope (he didn’t actually invent it) and discovered the four brightest moons of Jupiter. Since then, observational astronomy has made remarkable advancements in terms of the equipment used as well as the type, distance and number of objects observed.
Currently, observation in astronomy is all about detecting electromagnetic radiation from stars, planets, gas, dust, etc. Most objects can be seen through the visible spectrum of light they emit or reflect. As a result of the evolution in fields like electronics, photography and rocketry certain objects can be viewed in the other bands of the spectrum. The hottest stars are observed in the Ultra Violet bandwidth and the relatively cool ones in the Infra Red region. Entities possessing strong gravitational fields such as white dwarfs, neutron stars and black holes or those that are generated by explosions like supernovae remnants are perceived by the X-rays and Gamma rays they emit.
Beyond the protective cocoon of the Earth’s atmosphere (or magnetosphere), is a Universe full of radiation. Space radiation is different from the radiation we experience on Earth, such as X-rays and Gamma rays. It is comprised of atoms whose electrons have been stripped away as the atom accelerated in interstellar space to velocities nearing the speed of light and eventually only the nucleus remains. Space radiation poses a dire threat to human DNA, cells and tissues.
The most energetic Gamma rays are observed by scrutinizing their interaction with the Earth’s atmosphere. These Gamma rays have the ability to carry about million times the energy possessed by a typical Gamma ray travelling across space. For the most part, such rays traverse past the space-based detectors without any interaction. But once any of the Gamma rays strikes the atmosphere, a spontaneous cascade of particles that can be identified by the scintillating optical light emitted or through an interaction with a particle detector on the earth’s surface. However, the observation of the cosmic radiation and associated events are predominantly confined to experienced astronomers and scientists working in laboratories.
On a more fundamental level, observational astronomy is realized by ‘Star Gazing’ which extends to examining and enjoying the sky by locating and learning about constellations, galaxies, satellites, planets- ‘the wanderers’, comets-‘dirty snowballs’, meteor showers and other deep space objects by the unaided eye or with the help of a telescope.
Humans’ fascination with the night sky and everything it beholds is as old as the Creation itself. Astronomy being one of the ancient natural sciences, continues to enchant and inspire us with its magnanimity and mysteries.
As Plato rightly said, Astronomy compels the soul to look upwards and leads us from this world to another.
Observing the celestial bodies and accompanying phenomena, be it with the naked eye or telescopes, is destined to remain as a hobby, profession and passion of the people of the planet for centuries to come.