Back in December 1995, the Hubble Space Telescope created the now-famous "deep field" image, which took more than 300 exposures over the course of 10 days to peer deep into the history of the universe and spot more than 1,500 galaxies. A decade and a half later—after failures, upgrades, and the "ultra deep field"—Hubble marches on. Yesterday at the American Astronomical Society meeting, astronomers announced they'd used the telescope to look deeper into the past than ever before. The new image captures 7,500 galaxies of all kinds and shapes. The oldest galaxies in the image glow an intense blue, indicating high concentrations of the lighter elements hydrogen and helium.
Hydrogen fusion inside active stars creates heavier elements such as iron and nickel, which get spread across the universe when massive stars explode. These elements cause modern galaxies to glow in a rainbow of colors, so the extreme blueness of the ...
