The Visible Universe, Then and Now
Before the telescope was invented in 1608, our picture of the universe consisted of six planets, our moon, the sun and any stars we could see in the Milky Way galaxy. But as our light-gathering capabilities have grown, so too have the boundaries of the visible universe. Our interactive map shows how the known universe has grown from 1950 to 2011.
In the late 1700s, William Herschel, an English astronomer using a telescope with an 18.7-inch aperture, made the first systematic surveys of the skies, revealing more than 2,000 distant galaxies, nebulae and other objects invisible to the naked eye. Since then, increasingly powerful optical and radio telescopes have greatly expanded our store of knowledge.
In 1948, astronomers erected the 200-inch Hale Telescope at Palomar Observatory in California, and now, large-scale projects such as the Sloan Digital Sky Survey and NASA’s Kepler mission use sensitive digital imaging and computational power to collect and analyze hundreds of terabytes of data on millions of galaxies billions of light-years from Earth. With each additional bit of data, the universe itself grows larger.