Astronomy Picture of the Day . ... 26.12.1996 . ... To peer into our cosmos' unknown depths, astronomers must deploy new tools - and the classic new tool is a larger telescope. Pictured above is the new Hobby-Eberly Telescope (HET) which recently declared "first light" in western Texas. HET currently has the largest single mirror of any optical telescope -- 11 meters in diameter. ... HET 's huge size, on the other hand, allows it to see very dim objects and determine their spectrum. ...