Galilean Moons

Jupiter and three of the four Galilean Moons.
The Great Red Spot is visible in the Southern Equatorial Belt.
The fourth moon, Callisto, was outside the frame of this image.

The image was taken from our backyard on the 4th February 2013. The picture was created from a video clip taken with a QHY5v planetary camera attached to my 127mm Apo-refracting telescope. The image size was increased by the use of a 2.5x Revelation Barlow lens.  The still image was derived from the video clip using the freeware AutoStakkert and the final photograph was manipulated in Photoshop.

As Dorothy might have said "Its amazing what you can see from your own backyard"!

Europa

NASA  image of Europa taken from a distance of 417,489 miles
by the Cassini Spacecraft

Jupiter's moon Europa is an ice-world comprised of blocks which are broken apart and rafted into new positions. These geological features are indicative that Europa may have had a sub-surface ocean at some time in its past. Europa has its own magnetic field and this combined with other geological data lead scientist's to believe that a hidden ocean is mostly likely present on Europa today. The ridges shown in these images returned by NASA's Galileo spacecraft 1996-97 represent fractures in the ice-crust  caused by the gravitational influence of Jupiter. The Europa sub-surface ocean offers a potential habitat for extraterrestrial microbial life.

Ganymede

Ganymede image taken by the
New Horizon's Spacecraft on its way to Pluto.

This is New Horizons' best image of Ganymede, Jupiter's largest moon, taken with the spacecraft's Long Range Reconnaissance Imager (LORRI) camera at 10:01 Universal Time on February 27 from a range of 3.5 million kilometers (2.2 million miles). The longitude of the disk center is 38 degrees West and the image scale is 17 kilometers (11 miles) per pixel. Dark patches of ancient terrain are broken up by swaths of brighter, younger material, and the entire icy surface is peppered by more recent impact craters that have splashed fresh, bright ice across the surface.

With a diameter of 5,268 kilometers (3.273 miles), Ganymede is the largest satellite in the solar system.

This is one of a handful of Jupiter system images returned by New Horizons during its close approach to Jupiter.  Most of the data gathered by the spacecraft was stored onboard and was subsequently downlinked to Earth during March and April 2007.

Io

Two images of Io
taken by the New Horizons Spacecraft

This New Horizons image of Jupiter's volcanic moon Io was taken at 13:05 Universal Time during the spacecraft's Jupiter flyby on February 28, 2007. It shows the reddish color of the deposits from the giant volcanic eruption at the volcano Tvashtar, near the top of the sunlit crescent, as well as the bluish plume itself and the orange glow of the hot lava at its source. The relatively unprocessed image on the left provides the best view of the volcanic glow and the plume deposits, while the version on the right has been brightened to show the much fainter plume, and the Jupiter-lit night side of Io.

New Horizons' color imaging of Io's sunlit side was generally overexposed because the spacecraft's color camera, the super-sensitive Multispectral Visible Imaging Camera (MVIC), was designed for the much dimmer illumination at Pluto. However, two of MVIC's four color filters, the blue and "methane" filter (a special filter designed to map methane frost on the surface of Pluto at an infrared wavelength of 0.89 microns), are less sensitive than the others, and thus obtained some well-exposed views of the surface when illumination conditions were favorable. Because only two color filters are used, rather than the usual three, and because one filter uses infrared light, the color is only a rough approximation to what the human eye would see.

The red color of the Tvashtar plume fallout is typical of Io's largest volcanic plumes, including the previous eruption of Tvashtar seen by the Galileo and Cassini spacecraft in 2000, and the long-lived Pele plume on the opposite side of Io. The color likely results from the creation of reddish three-atom and four-atom sulfur molecules (S3 and S4) from plume gases rich in two-atom sulfur molecules (S2 After a few months or years, the S3 and S4 molecules recombine into the more stable and familiar yellowish form of sulfur consisting of eight-atom molecules (S8), so these red deposits are only seen around recently-active Io volcanoes  Though the plume deposits are red, the plume itself is blue, because it is composed of very tiny particles that preferentially scatter blue light, like smoke. Also faintly visible in the left image is the pale-colored Prometheus plume, almost on the edge of the disk on the equator at the 9 o'clock position.

Io was 2.4 million kilometers from the spacecraft when the picture was taken, and the center of Io's disk is at 77 degrees West longitude, 5 degrees South latitude. The solar phase angle was 107 degrees.

Credits

NASA/JPL

NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute