The COSMOS-Webb survey will map 0.6 square degrees of the sky — about the area of three full Moons — using the James Webb Space Telescope’s Near Infrared Camera (NIRCam) instrument, while simultaneously mapping a smaller 0.2 square degrees with the Mid Infrared Instrument (MIRI). (JEYHAN KARTALTEPE (RIT); CAITLIN CASEY (UT AUSTIN); AND ANTON KOEKEMOER (STSCI) GRAPHIC DESIGN CREDIT: ALYSSA PAGAN (STSCI))

What James Webb’s Most Ambitious First-Year Science Mission Will Teach Us

Hubble, our greatest space-based observatory today, is just the beginning.

The Hubble Space Telescope has been astronomy’s most revolutionary observatory in history.

The stars and galaxies we see today didn’t always exist, and the farther back we go, the closer to an apparent singularity the Universe gets, as we go to hotter, denser, and more uniform states. While Hubble has provided humanity with our deepest views of the cosmos to date, even it is limited in how far back it can ‘see’ the distant Universe. (NASA, ESA, AND A. FEILD (STSCI))

For over 30 years, it’s taken us to the farthest depths of space.

Only because this distant galaxy, GN-z11, is located in a region where the intergalactic medium is mostly reionized, can Hubble reveal it to us at the present time. To see further, we require a better observatory, optimized for these kinds of detection, than Hubble: exactly what James Webb will deliver. (NASA, ESA, AND A. FEILD (STSCI))

Hubble’s deep-field views have revealed galaxies to unprecedented distances and faintnesses.

The Hubble eXtreme Deep Field (XDF) may have observed a region of sky just 1/32,000,000th of the total, but was able to uncover a whopping 5,500 galaxies within it: an estimated 10% of the total number of galaxies actually contained in this pencil-beam-style slice. The remaining 90% of galaxies are either too faint or too red or too obscured for Hubble to reveal. (HUDF09 AND HXDF12 TEAMS / E. SIEGEL (PROCESSING))

Despite these successes, its narrow field-of-view restricts its views to under 1% of the cumulative sky.

A close-up of over 550,000 science related observations made by the Hubble Space Telescope. The locations and sizes of the observations made can all be seen here. Although they are located in many different places, the total sky coverage is minimal. Many of the observations are clustered in the galactic plane or around surveys such as COSMOS, GOODS, or Frontier Fields. (NADIEH BREMER / VISUAL CINNAMON)

With larger-aperture, infrared capabilities, NASA’s James Webb Space Telescope will surpass Hubble in many ways.