Answer:
Muslim astronomers made many significant accomplishments in the field of astronomy. Here are some of their major contributions:
1. Development of the astrolabe: Muslim astronomers developed the astrolabe, an ancient astronomical instrument that was used for solving problems related to time and the position of the stars.
2. Measurement of the Earth's circumference: Muslim astronomer and geographer Al-Farghani (also known as Alfraganus) made an estimate of the Earth's circumference that was close to the current-day value.
3. Accurate observations of the positions of celestial objects: Muslim astronomers made extensive observations of the positions of celestial objects and developed accurate methods for measuring their positions.
4. Calculation of the length of the year: Muslim astronomer and mathematician Al-Khwarizmi developed a method for calculating the length of the year with a high degree of accuracy.
5. Cataloguing of stars: Muslim astronomers catalogued many stars and constellations, and developed methods for naming and organizing them.
6. Advancements in trigonometry: Muslim mathematicians developed new trigonometric techniques, which were used extensively in astronomical calculations.
7. Advancements in optics: Muslim scientists made significant advancements in optics, including the development of the camera obscura and the study of refraction and reflection.
Overall, Muslim astronomers made significant contributions to the field of astronomy, and their work was instrumental in advancing scientific knowledge and understanding in the Islamic world and beyond.