Hubble Space Telescope (HST) has captured many unique and exceptional photographs. The picture below is another. What we are seeing is a star in the beginning stages of its death throes.
Stars live by turning hydrogen into helium in their cores. But stars have only a finite amount of fuel in their cores and surrounding layers to burn. When the fuel starts to run out the star burns whatever it can to survive. In this amazing HST image, U Cam is a star that is running out of time and fuel.
It is unstable and ever thousand years or so it puffs off a layer of gas in an almost perfectly spherical shell which HST captured in this photo. The star's image is greatly bloated as it would be only one pixel across but due to the overexposure necessary to capture the dimmer shell it has saturated the camera's sensors.
Our own Sun will look like this in about 5 billion years as it will become a Red Giant that puffs away outer layers until only the white hot core remains - becoming a white dwarf star with a surrounding nebula of gas and dust.
Read More About It: http://www.nasa.gov/mission_pages/hubble/science/red-bubble.html