The primary mirror of the JWST, the Optical Telescope Element, is composed of 18 hexagonal mirror segments made of gold-plated beryllium which combine to create a 6. 5-meter (21 ft; 260 in) diameter mirror that is much larger than the Hubble’s 2. 4-meter (7. 9 ft; 94 in) mirror. Unlike the Hubble, which observes in the near ultraviolet, visible, and near infrared (0. 1 to 1 μm) spectra, the JWST will observe in a lower frequency range, from long-wavelength visible light through mid-infrared (0. 6 to 27 μm), which will allow it to observe high redshift objects that are too old and too distant for the Hubble to observe. The telescope must be kept very cold in order to observe in the infrared without interference, so it will be deployed in space near the Earth–Sun L2 Lagrangian point, and a large sunshield made of silicon- and aluminum-coated Kapton will keep its mirror and instruments below 50 K (−220 °C; −370 °F).
Among the ringed gas giant planet Saturn's amazing collection of 62 diverse, bizarre, and beautiful moons and moonlets, sometimes one of them just seems to stand out in the crowd. Such a moon is little Methone. Looking like a shiny white egg in Space, and composed of very lightweight fluffy stuff, Methone is less dense than any other known moon or asteroid in our Solar System. In March 2013, astronomers announced at the 44th Lunar and Planetary Science Conference held in the Woodlands, Texas, that this strange little 5-kilometer-size moon is one of a batch of Space eggs in orbit around Saturn!
The discovery of Makemake's little moon increases the parallels between Pluto and Makemake. This is because both of the small icy worlds are already known to be well-coated in a frozen shell of methane. Furthermore, additional observations of the little moon will readily reveal the density of Makemake--an important result that will indicate if the bulk compositions of Pluto and Makemake are similar. "This new discovery opens a new chapter in comparative planetology in the outer Solar System," Dr. Marc Buie commented in the April 26, 2016 Hubble Press Release. Dr. Buie, the team leader, is also of the Southwest Research Institute.
This important measurement was made using Cassini's INMS instrument, which detects gases with the goal of determining their composition. INMS was designed to sample the upper atmosphere of Saturn's large, smoggy moon Titan. However, after Cassini's surprising discovery of a tall plume if icy spray erupting from cracks on Enceladus in 2005, planetary scientists turned its detectors to that small moon.