APOD: 2022 March 23 - The Bubble Nebula from Hubble

Good morning, Rallypoint, and welcome to the March 23rd Hump Day edition of the Astronomy Picture of the Day (APOD): "The Bubble Nebula from Hubble." The Bubble Nebula (NGC 7635) lies 7,100 light years away in the constellation Cassiopeia, and was discovered in 1787 by William Herschel. It is produced by the star you see at about 10 o'clock in the overall cloud complex. This star is 45 times more massive than our own Sun. Gas from the star escapes away into space as a "stellar wind" moving at over 4 million miles per hour. This outflow creates the outer edge of the bubble as it interacts with surrounding colder regions. Researchers suggest that the areas at 4 o'clock are much denser and colder than other quadrants about the star, giving the Bubble Nebula its asymmetric shape relative to its host star.

Today's APOD is a composite image of datasets collected from all three Wide Field Planetary Cameras (WFPC, WFPC2, and WFPC3) that have flown aboard Hubble. Why were there three? The first WFPC was not able to focus correctly due to a tiny error in the curvature of Hubble's main mirror (anyone remember that?). In December 1993, astronauts replaced the camera with a second-generation version, WFPC2. WFPC3 was installed in May 2009, and WFPC2 was brought back to Earth. It is now on display at the Smithsonian Air and Space Museum in Washington.