The James Webb Space Telescope will be launched in 2020. It's going to be fantastic. "It will search for the very first stars to shine in the Universe."

The successor to the Hubble Space Telescope has been delayed yet again and will not now launch until "approximately May 2020".

JWST is a joint venture between the American space agency and its European and Canadian counterparts.

When it eventually goes into space, it will search for the very first stars to shine in the Universe.

To achieve this ambition, it will deploy a 6.5m-wide mirror, giving the observatory roughly seven times the light-collecting area of Hubble.

Allied to instruments that are sensitive in the infrared, Webb will be tuned to detect the faint, "stretched" glow of objects that originally shone more than 13.5 billion years ago.