Continuing our top 10 ranges, today we will write about top 10 largest cities in the world by land area.
California-based skywatcher Larry Van Vleet captured a photo which shows a giant bubble of gas blown by the nebula NGC 7635, also known as the Bubble nebula. Van Vleet used a RCOS 16 Truss telescope and Apogee U16M to capture the photo from his Sierra Remote Observatories in Shaver Lake,Calif., in August. The bubble was created by fierce stellar winds and intense radiation from a nearby star, which likely has a mass 10 to 20 times that of the sun. The bubble is located 7,100 light-years from Earth in the constellation Cassiopeia, and is about 6 light-years wide. It glows pink because of the red, hot gas that surrounds it. Emission nebulas are clouds of high temperature gas.
The atoms in the cloud are energized by ultraviolet light from a nearby star and emit radiation as they fall back into lower energy states. The relatively bright star at about the 11 o’clock position within the prominent bubble is known as BD 60°2522 or SAO 20575 and is the source of the bubble shape. The star is known as a Wolf-Rayet star, which is an O-type star that is nearing the supernova stage. These stars are incredibly hot.