अवलोकन संबंधी खगोल विज्ञान में महत्वपूर्ण प्रगति किस काल की शुरुआत में दूरबीन के आविष्कार और अनुप्रयोग के साथ हुई?

Who was the Italian astronomer that first pointed a systematically constructed telescope at the night sky in 1609?

The dwarf planet Ceres, the largest object in the asteroid belt, was discovered by an astronomer from which country?

In which year was the dwarf planet Pluto discovered by astronomer Clyde Tombaugh?