The 3 Banu Musa brothers were among the most important scientists in Baghdad in the 9th century during the Islamic Golden Age.
They were excelling in astronomy, mechanics, and geometry.
For this reason they were employed in the famous House of Wisdom, a library and a translation center in Baghdad.
As a result scientific works from all over the world were translated to Arabic. Then Islamic scholars used this knowledge while adding their own ideas and concepts in order to develop their inventions in many domains.
Coming back to The Banu Musa brothers, they invented automatic machines and mechanical devices. Then described a 100 of them in their “Book Of Tricks” or “Book of Ingenious Devices” (“Kitab al-Hiyal”)
Most importantly their contribution in the field of mechanical sciences set the foundations for modern mechanics and hydraulics. Their work inspired other famous Muslim scientists like Al-Jazari three centuries after.
Basically all these researches and inventions paved the way for Europe’s industrial revolution.
As for the astronomy, one of their many achievements was about the solar year. Indeed they used to spend their time observing the sky. Which lead them to conclude that a solar year lasts for 365 days and six hours.