Beyond Earth | Class 6 Science Notes

12.1 Stars and Constellations

When we look up at the night sky, we see many stars that vary in brightness; some are bright, others dim. Stars are luminous celestial bodies that shine by producing their own light through nuclear reactions occurring in their cores. Groups of stars sometimes appear to form patterns resembling familiar shapes such as animals, objects, or characters from stories. Ancient people, fascinated by the night sky, identified these star patterns and named them based on their cultural stories and imaginations. These patterns, called constellations, helped people recognize stars and navigate before modern technology and compasses were invented. Even today, constellations serve as a backup method for navigation in emergencies. The International Astronomical Union (IAU) standardized the sky by defining 88 constellations, dividing the entire sky into distinct regions. The term 'constellation' now refers both to the patterns and the defined regions of the sky. For example, the constellation Orion is often depicted as a hunter with a distinctive belt of three stars. Nearby constellations include Canis Major, representing the hunter's dog, which contains Sirius, the brightest star in the night sky. Indian astronomy uses the term nakṣhatra for certain stars or groups of stars, such as Ārdrā (Betelgeuse in Orion) and Kṛittikā (Pleiades in Taurus).

📊 Diagram: Since different cultures denoted the constellation boundaries in different ways, an internationally agreed set of constellation boundaries were defined by the International Astronomical Union (IAU) in; Some constellations are shown in Fig. 12.3. The stars are joined by imaginary lines, drawn for easy identification. The constellation Orion is often represented as a hunter. There are three stars in t; Fig. 12.3: Some constellations and stars; More to know!

🔗 Connection: This section introduces constellations and stars, setting the stage for the next section about important constellations like the Big Dipper, Little Dipper, and the Pole Star.