September 10, 1995
The night sky on your birthday is never quite the same twice — the planets shift, the constellations drift, the Moon wears a different phase.
White Dwarfs Cool
Birthday · September 10, 1995
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APOD published September 10, 1995. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
The circled stars in the above picture are from a class that is hard to see in the cosmos: white dwarfs. The entire photo covers a small region near the center of a globular cluster known as M4. Researchers using the Hubble Space Telescope discovered a large concentration of white dwarfs in M4. This was expected - low mass stars, including the Sun, are known to evolved to the white dwarf stage. White dwarfs do not usually evolve further, they just gradually cool down from their high temperatures. It is hoped that studying how these stars cool could lead to a better understanding of their ages, of the age of their parent globular cluster, and hopefully even the age of our universe!