Free Astronomy Magazine March-April 2022

MARCH-APRIL 2022 ready been formed but before grav- ity drew them together into the first galaxies. This process, from stars to galaxies within the architecture of the early cosmos, will hopefully be revealed in detail by Webb. In terms of design and implementa- tion, Webb’s greatest strength for astronomy – infrared sensitivity – is also its greatest challenge for engi- neers. Just as one would not find much success trying to measure the cosmic microwave background from the inside of a running microwave oven, nor to try to use a 12” Dobson- ian telescope to observe distant galaxies (nor arguably anything dim- mer than Saturn) during their noon- time lunch break, the usability of an infrared telescope is limited dramat- ically by its proximity to both in- frared-emitting objects and to the heat being generated by its own electronics. The seeing from the ground for infrared astronomy is poor on its best days, as Earth’s at- mosphere is not only being actively heated by the Sun but is also itself an excellent infrared absorber of radiation coming from any object duction. Hubble, for instance, has just taken us back to Chapter Four, a redshift of about z=11. The Cosmic Background Explorer, or COBE, gave us a notion of the shape of the book binding through its measurement of the cosmic background radiation. Webb gives us access to Chapters Two and Three, corresponding to a redshift of z= 20, a time 180 million years after the Big Bang when the first stars are theorized to have al- A n artist’s side-on view of the equipment bus and solar pan- els, five stacked sunshields, and the honeycomb mirror array and detec- tors. [NASA GSFC/CIL/Adriana Man- rique Gutierrez]