Andromeda Light Reaching Earth Left 2.5 Million Years Ago as Early Humans Made Stone Tools
Updated
Updated · spacedaily.com · Jun 2
Andromeda Light Reaching Earth Left 2.5 Million Years Ago as Early Humans Made Stone Tools
1 articles · Updated · spacedaily.com · Jun 2
Summary
2.5 million-year-old light from the Andromeda Galaxy is reaching Earth now, meaning naked-eye observers see M31 as it existed when the genus Homo had only recently emerged.
NASA places Andromeda 2.5 million light-years away, so its photons began crossing intergalactic space around the era of the earliest Oldowan stone tools in East Africa.
M31 is the nearest large galaxy and the most distant object widely visible without a telescope, though observers usually see only its bright core because its light is spread thinly across a broad disk.
About 1 trillion stars fill Andromeda, which spans roughly 260,000 light-years and is moving toward the Milky Way at about 110 kilometers per second, with a merger expected in 4.5 billion years.