The James Webb Space Telescope is the successor to the Hubble's throne. In order to pick up extremely faint infra-red signals from extremely distant stars and galaxies, the JWST has to be extremely cold. Any noise from the IR radiation of the Sun or Earth would make it impossible to see as far into the past as scientists want to.
Thus, the JWST has to be a million miles from the earth, protected by a six-layer heat shield as big as a tennis court. This will allow the Webb Telescope to peer into the deepest reaches of space, through clouds of dust into stellar nurseries and back in time 13.4 billion years.
Not only will we get the most detailed views of our universe ever, but the JWST will provide insights into how solar systems, galaxies, stars and even the Universe were formed.