HUT

Hopkins Ultraviolet Telescope

According to the big bang theory, the billions of galaxies we see today condensed out of a sea of matter, mainly hydrogen and helium gas, that filled the early Universe. But astronomers were uncertain about the quantity and composition of that primordial matter. One major project that focused on that question was HUT, the Hopkins Ultraviolet Telescope. HUT was designed to detect and measure the intergalactic medium, the gas between the galaxies.

HUT was part of a package of instruments called the Astro Observatory, which was twice carried into orbit by the Space Shuttle. Astro remained in the Shuttle's payload bay and was operated by astronauts.

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Observations

HUT studied the matter spread throughout intergalactic space. HUT confirmed that the composition of the matter fit the predictions of the big bang model. But other findings were startling. HUT's data indicated that all the stars and galaxies combined represent only a fraction-perhaps 20 percent-of the material in the known Universe. The rest consists of gas spread thinly throughout space.

This image, compiled from HUT data, is a simulated view of the distribution of matter in the early Universe, before the formation of galaxies. The darker the shade, the greater the density. Like COBE's map of an even younger Universe, HUT's map shows a lumpiness in the distribution of matter.