November 21, 1996
On the day you were born, the universe did what it has always done best: transformed chaos into beauty.
The Blue Snowball Planetary Nebula Credit:
Birthday · November 21, 1996
A little universe, just for you
Your date.
Ready to give.
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APOD published November 21, 1996. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
Will the Sun one day look like - a blue snowball? Maybe! The Blue Snowball is a planetary nebula - and in 5 billion years the Sun will throw off its outer layers and go through a planetary nebula phase. A star can appear "normal" only so long as there are sufficient nuclear reactions in its core. Soon thereafter, gravity will win out and compress the stellar core to higher temperatures. Eventually the core becomes a white dwarf. These high temperatures somehow cause the expulsion of star's outer layers, creating a planetary nebula such as the Blue Snowball pictured above. Although the Blue Snowball, also known as NGC 7662, does appear blue, the above picture's colors are not real and were chosen to highlight the emission of certain ions in the nebula. Many things are still not known about planetary nebula, including details of the physical mechanism that creates the nebula, and the reason for fast knots of gas in the outer regions known as fliers.