Astro Glossary

James Webb Space Telescope

The next big space telescope is named in honor of James Webb, a former head of NASA who oversaw the Mercury and Gemini missions that prepared the agency for the Apollo Moon flights. It will observe the universe at infrared wavelengths, and will be deployed one million miles from Earth. That location will shield it from the warmth of Earth, which produces a lot of infrared energy.

Japanese Astronomy and Folklore

Japanese Space Program

JUICE Mission to Jupiter

Jupiter Ice Moons Explorer (JUICE) is a European spacecraft designed to study the three largest moons of Jupiter: Ganymede, Callisto, and Europa. All three moons appear to have large oceans of liquid water beneath their icy crusts. Europa is of particular because its crust is thinner and it may have more interior heat to warm the ocean, making it both a more comfortable abode for possible microscopic life and an easier world to probe. JUICE is scheduled to enter orbit around Jupiter in July 2031. It will make multiple passes by all three moons, then settle into orbit around Ganymede in December 2034. That will make it the first spacraft to orbit any planetary moon other than Earth's. 

Juno Mission

A spacecraft designed to study Jupiter’s interior and atmosphere by orbiting from pole to pole. It will obtain precise measurements of the giant planet’s magnetic and gravitational fields, and peer deep into its turbulent clouds.

Jupiter

The fifth planet from the Sun and the largest planet in our solar system. Jupiter orbits the Sun at an average distance of 5.2 time Earth’s distance (about 465 million miles/745 million km). The planet has a mass 318 times the mass of Earth and a radius 11.2 times the radius of Earth. Jupiter is a gas planet and has no solid surface. It is made of hydrogen and helium, with trace amounts of ammonia, water vapor, and methane. The most recognizable features of the planet are its bands of clouds and a giant storm visible from Earth called the Great Red Spot. Jupiter has more than 60 known moons, the largest of which are Io, Europa, Ganymede, and Callisto.

Jupiter's Great Red Spot

A raging red swirling storm located in Jupiter’s upper atmosphere. The storm has been observed since at least the late 1800s, and perhaps as far back as the 1600s. It appears to rotate counterclokwise once every six days. Its size varies from about 1 to 2 times the diameter of Earth, while its color varies from pale pink to vivid red.

Jupiter's Moons

Jupiter has almost 80 known moons. The four largest, known as Galilean moons for their discoverer, Galileo Galilei, are Io, Europa, Ganymede, and Callisto. Ganymede is the largest moon in the solar system.