December 31, 1995
The elements that make you — the calcium in your bones, the oxygen in your lungs — were scattered across space by dying stars long before...
The X-ray Sources of M31
Birthday · December 31, 1995
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APOD published December 31, 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.
Just like our own Milky Way Galaxy, the nearest major galaxy M31 has many star systems spewing high energy radiation. High energy X-radiation is visible to certain satellites in Earth orbit such as ROSAT - which took the above picture. The X-ray sources in M31 occur in globular clusters, the spiral arms, and near the galaxy's center. Probably most of these sources are accretion disk binary star systems. M31 has more X-ray sources near its center than our Galaxy, and the reason for this is currently unknown.