page_title: Extraterrestrial sky
section_title: Jupiter's moons as seen from Jupiter
hierarchical_section_title: Extraterrestrial sky / Jupiter / Jupiter's moons as seen from Jupiter
caption_attribution_description: English: This is an artist's concept of a plume of water vapor thought to be ejected off the frigid, icy surface of the Jovian moon Europa, located about 500 million miles (800 million kilometers) from the sun. Spectroscopic measurements from NASA's Hubble Space Telescope led scientists to calculate that the plume rises to an altitude of 125 miles (201 kilometers) and then it probably rains frost back onto the moon's surface. Previous findings already pointed to a subsurface ocean under Europa's icy crust.
context_page_description: In astronomy, an extraterrestrial sky is a view of outer space from the surface of an astronomical body other than Earth.
  The only extraterrestrial sky that has been directly observed and photographed by astronauts is that of the Moon. The skies of Venus, Mars and Titan have been observed by space probes designed to land on the surface and transmit images back to Earth.
  Characteristics of extraterrestrial sky appear to vary substantially due to a number of factors. An extraterrestrial atmosphere, if present, has a large bearing on visible characteristics. The atmosphere's density and chemical composition can contribute to differences in colour, opacity and the presence of clouds. Astronomical objects may also be visible and can include natural satellites, rings, star systems and nebulas and other planetary system bodies.
context_section_description: Aside from the Sun, the most prominent objects in Jupiter's sky are the four Galilean moons. Io, the nearest to the planet, would be slightly larger than the full moon in Earth's sky, though less bright, and would be the largest moon in the Solar System as seen from its parent planet. The higher albedo of Europa would not overcome its greater distance from Jupiter, so it would not outshine Io. In fact, the low solar constant at Jupiter's distance (3.7% Earth's) ensures that none of the Galilean satellites would be as bright as the full moon is on Earth, and neither would any other moon in the Solar System. 
  All four Galilean moons stand out because of the swiftness of their motion, compared to the Moon. They are all also large enough to fully eclipse the Sun.
  Because Jupiter's axial tilt is minimal, and the Galilean moons all orbit in the plane of Jupiter's equator, solar eclipses are quite common.
caption: Water vapor plume on Europa (artist concept; December 12, 2013)[23]
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