From the discovery that the Milky Way is just one galaxy among billions to the stunning revelation that these galaxies are speeding away from each other faster every second, this episode investigates the universe's distant past - and its future. Now, modern telescopes have added a mysterious new twist to the plot: the vast majority of the stuff of the universe is invisible, tied up in dark matter and dark energy. But what are these mysterious dark forces? A new generation of telescopes is embarking on a mission impossible to see the unseeable and answer one of the greatest unsolved mysteries of the cosmos.

Encoded with permission for digital streaming by Infobase on December 08, 2013. Learn360 is distributed by Infobase for Films for the Humanities & Sciences, Cambridge Educational, Meridian Education, and Shopware.

Space Telescopes Explore the Universe (1:41) -- Sponsors: Hunting the Edge of Space (1:06) -- Age of Discovery (2:04) -- Expanding Perceptions (1:44) -- Mt. Wilson Observatory (3:24) -- The Hale Telescope (4:09) -- Hubble Finds a Galaxy Beyond Our Own (2:58) -- Billions of New Galaxies Discovered (1:22) -- Red Shift of Light Waves (3:31) -- The Expanding Universe (2:15) -- Sloan Digital Sky Survey (1:39) -- The Big Bang Theory (2:05) -- Radio and Microwaves (1:52) -- Afterglow of the Big Bang (2:08) -- Wilkinson Microwave Anisotropy Probe (WMAP) (3:27) -- Visions of the Hubble Space Telescope (3:07) -- The Hubble Deep Field (2:35) -- The Keck Observatory Mirrored Telescopes (4:49) -- Dark Energy (1:28) -- Dark Matter (2:07) -- Future Investigations (2:37) -- Credits: Ever Expanding Universe: Telescopes- Hunting the Edge of Space (1:57).