Earth, Moon, and Jupiter, as Seen From Mars | Mars News Earth, Moon, and Jupiter, as Seen From Mars View more images at the MSSS release page . Image Credit: NASA/JPL-Caltech/MSSS What does Earth look like when viewed from Mars? At 13:00 GMT on 8 May 2003, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) had an opportunity to find out. In addition, a fortuitous alignment of Earth and Jupiter---the first planeary conjunction viewed from another planet---permitted the MOC to acquire an image of both of these bodies and their larger satellites. At the time, Mars and the orbiting camera were 139 million kilometers (86 million miles) from Earth and almost 1 billion kilometers (nearly 600 million miles) from Jupiter. The orbit diagram, above, shows the geometry at the time the images were obtained. Because Jupiter is over 5 times farther from the Sun than Earth, two different exposures were needed to image the two planets. Mosaiced together, the images are shown above (top picture).

The composite has been highly contrast-enhanced and "colorized" to show both planets and their satellites. The MGS MOC high resolution camera only takes grayscale (black-and-white) images; the color was derived from Mariner 10 and Cassini pictures of Earth/Moon and Jupiter, respectively, as described in the note below. View more images at the MSSS release page . Image Credit: NASA/JPL-Caltech/MSSS Earth/Moon: This is the first image of Earth ever taken from another planet that actually shows our home as a planetary disk. Because Earth and the Moon are closer to the Sun than Mars, they exhibit phases, just as the Moon, Venus, and Mercury do when viewed from Earth. As seen from Mars by MGS on 8 May 2003 at 13:00 GMT (6:00 AM PDT), Earth and the Moon appeared in the evening sky. The MOC Earth/Moon image has been specially processed to allow both Earth (with an apparent magnitude of -2.5) and the much darker Moon (with an apparent magnitude of +0.9) to be visible together.

The bright area at the top of the image of Earth is cloud cover over central and eastern North America. Below that, a darker area includes Central America and the Gulf of Mexico. The bright feature near the center-right of the crescent Earth consists of clouds over northern South America. The image also shows the Earth-facing hemisphere of the Moon, since the Moon was on the far side of Earth as viewed from Mars. The slightly lighter tone of the lower portion of the image of the Moon results from the large and conspicuous ray system associated with the crater Tycho. Jupiter/Galilean Satellites: When Galileo first turned his telescope toward Jupiter four centuries ago, he saw that the giant planet had four large satellites, or moons. These, the largest of dozens of moons that orbit Jupiter, later became known as the Galilean satellites. The larger two, Callisto and Ganymede, are roughly the size of the planet Mercury; the smallest, Io and Europa, are approximately the size of Earth's Moon. This MGS MOC image, obtained from Mars orbit on 8 May 2003, shows Jupiter and three of the four Galilean satellites: Callisto, Ganymede, and Europa.

At the time, Io was behind Jupiter as seen from Mars, and Jupiter's giant red spot had rotated out of view. This image has been specially processed to show both Jupiter and its satellites, since Jupiter, at an apparent magnitude of -1.8, was much brighter than the three satellites. January guide to the bright planets | Astronomy Essentials | EarthSky January guide to the bright planets By Bruce McClure and Deborah Byrd in Astronomy Essentials | January 12, 2017 In January 2017, Venus blazes in the west after sunset. Mars is fainter, and nearby. The other 3 bright planets – Jupiter, Saturn and Mercury – light up the hours before sunrise. Next moon and planet pairing will be centered on or near January 19, 2017. The moon will sweep past Jupiter and the star Spica. Read more . Two of the five bright planets rise to great prominence in January 2017 sky. Venus rules over the evening sky while Jupiter rules the morning. Venus, the brightest planet, blazes in the west first thing at dusk, and reaches its greatest elongation as the “evening star” on January 12 .

Jupiter, the second-brightest planet, lords over the eastern half of sky between midnight and sunrise. Mars is near Venus in the evening sky, but it’s higher up and much fainter than Venus, setting in the west shortly after Venus does. Meanwhile, Saturn appears in the southeastern sky before dawn. Mercury a short hop beneath Saturn, just as darkness is giving way to morning twilight. Follow the links below to learn more about planets in January 2017. Skywatcher, by Predrag Agatonovic . Brilliant Venus is the “evening star.” Okay, it’s not a star. It’s a planet. But people will call it the evening star all the same. In these past weeks, many have noticed Venus and been amazed at its brilliance in the west after sunset. It’s the brightest planet and very, very bright, to reach its greatest evening elongation on January 12 . Be sure to catch the waxing crescent moon near Venus in early January, as displayed on the sky chart above. Click here for details . Watch for Venus to close the gap between itself and Mars.

These two visible evening planets will be closer together on the sky’s dome by the month’s end and closer yet in early February 2017. From mid-northern latitudes (U.S. and Europe), Venus sets about four hours after the sun throughout the month. At mid-southern latitudes (Australia and South Africa), Venus sets about about three hours after the sun in early January and about 2.5 hours after sun by the month’s end. The moon will sweep by Venus and Mars again before January, 2017 ends. Read more . You needed a telescope to see Neptune … but Venus, the brightest planet, was in conjunction with Neptune, the Hof our solar system’s major planets, on January 12, 2017. Photo by Borislava Georgieva in Bulgaria. Mars, east of Venus, until mid-evening. After appearing as a bright red light in our sky last May and June 2016, Mars now appears only modestly bright (though possibly still ruddy), above dazzling Venus. Venus is so bright that it pops out almost immediately after sunset, but you’ll have to wait until nightfall to see fainter Mars.

Look for the moon close to Mars for a few evenings, on or near January 2 or 3 . From mid-northern latitudes (U.S. and Europe), look for the red planet Mars to set in the west around 9 to 10 p.m. all month long. At mid-southern latitudes (Australia and South Africa), Mars sets in the west around 9 to 10 p.m. (10 to 11 p.m. summer time). Mars will linger in our sky for several more months. Keep in mind, however, that Earth is traveling away from Mars as we speak – moving far ahead of this planet in the endless race around the sun – so Mars is dimming in our evening sky. Mars is in its long, lingering, relatively inconspicuous phase now. It’ll be still visible in the west to the unaided eye – though not prominent – during its conjunction with Uranus on the evening of February 27, 2017. Mars won’t make its transition from the evening to morning sky until July 27, 2017.

Even so, Mars’ stature in the evening sky will continue to diminish to that of a rather faint “star,” and we expect few – if any – skywatchers to observe the conjunction of Mars and Mercury in the evening sky on June 28, 2017. The conjunction of Mars and Venus in the morning sky on October 5, 2017, may well present the first good opportunity to spot Mars in the morning sky when it returns from being behind the sun on July 27, 2017. Looking for a sky almanac? EarthSky recommends… View larger | Mikhail Chubarets in the Ukraine made this chart. It shows the view of Mars through a telescope in 2016. We never see Mars as a disk like this with the eye alone. But you can see why Mars was bright to the eye in 2016, and is now fading. Watch for the moon to meet up with Saturn on or near Janaury 24, 2017. Read more . Saturn returns to the morning sky. Saturn swung behind the sun on December 10, 2016, transitioning from the evening to morning sky.

In both the Northern and Southern Hemispheres, Saturn returned to the morning sky in late December 2016. In early January, Saturn rises in the east about two hours before the sun, and by the month’s end, Saturn comes up several hours before sunrise. Be sure to let the waning crescent moon guide you to Saturn (and the nearby star Antares) for several days, centered on or near January 24 . Saturn, the farthest world that you can easily view with the eye alone, appears golden in color. It shines with a steady light. Binoculars don’t reveal Saturn’s gorgeous rings, by the way, although binoculars will enhance Saturn’s golden color. To see the rings, you need a small telescope. A telescope will also reveal one or more of Saturn’s many moons, most notably Titan . Saturn’s rings are inclined at nearly 27o from edge-on, exhibiting their northern face. In October 2017, the rings will open most widely, displaying a maximum inclination of 27o. As with so much in space (and on Earth), the appearance of Saturn’s rings from Earth is cyclical.

In the year 2025, the rings will appear edge-on as seen from Earth. After that, we’ll begin to see the south side of Saturn’s rings, to increase to a maximum inclination of 27o by May 2032. Tom Wildoner over-exposed Saturn itself to capture this view of Saturn’s moons on June 25, 2016. Visit Tom at LeisurelyScientist.com . Contrasting the size of Saturn and its rings with our planet Earth via Hubble Heritage Team . The moon swings by the planet Jupiter and the star Spica for several days, centered on or near January 19, 2017. Read more . Bright Jupiter lords over the morning sky. Jupiter’s increasing prominence as the “morning star” will be hard to overlook. To see Jupiter, seek out the brightest starlike object in the predawn sky or the morning twilight and that’ll be the king planet Jupiter! Jupiter rises in the east at late night and soars to its highest point in the sky at or near dawn. From mid-northern latitudes, like those in the U.S. and Europe, Jupiter rises around one hour after the midnight hour in early January.

By the month’s end, Jupiter rises roughly one hour before midnight. From mid-southern latitudes (Australia), look for Jupiter to rise around midnight in early January and about two hours before midnight by the end of the month. If you’re not a night owl, your best bet for catching Jupiter is to wake up before sunrise to see this brilliant beauty of a planet lighting up the predawn and dawn sky. Watch for the waning moon to join up with Jupiter for several days, centered on or near January 19 . See the above sky chart. By the way, Jupiter shines in front of the constellation Virgo, near Virgo’s brightest star, Spica . Jupiter serves a great reference for learning the constellations of the zodiac , because Jupiter stays in each constellation for roughly a year. So use Jupiter to become familiar with the star Spica and the constellation Virgo, starting now, and throughout 2017. If you have binoculars or a telescope, it’s fairly easy to see Jupiter’s four major moons, which look like pinpricks of light on or near the same plane.

They are often called the Galilean moons to honor Galileo, who discovered these great Jovian moons in 1610. In their order from Jupiter, these moons are Io, Europa, Ganymede and Callisto. Jupiter and its four major moons via Jan Sandberg These moons circle Jupiter around the Jovian equator. In cycles of six years, we view Jupiter’s equator edge-on. So, in 2015, we got to view a number of mutual events involving Jupiter’s moons through a high-powered telescope. Click here or here or here for more details. Although Jupiter’s axial tilt is only 3o out of perpendicular relative to the ecliptic (Earth’s orbital plane), Jupiter’s axis will tilt enough toward the sun and Earth so that the farthest of these four moons, Callisto, will NOT pass in front of Jupiter or behind Jupiter for a period of about three years, starting in late 2016. During this approximate 3-year period, Callisto will remain “perpetually” visible, alternately swinging “above” and “below” Jupiter. Click here for a Jupiter’s moons almanac, courtesy of Sky & Telescope.

Eliot Herman in Tucson, Arizona caught Mercury on the night of December 11, 2016, amidst crepuscular rays from the setting sun. Look for the thin waning crescent moon and the planet Mercury low in the sky as the predawn darkness gives way to dawn. Who knows? Someone might even catch the moon below Mercury on January 26! The green line depicts the ecliptic – Earth’s orbital plane projected on the sky. Read more . Mercury in the morning sky. Mercury transitioned from the evening to morning sky on December 28, 2016. This month, beginning in the second week of January 2017, Mercury should climb far enough from the glare of sunrise to become visible in the morning sky from both the Northern Hemisphere and the Southern Hemisphere. Saturn rises before Mercury does, so use Saturn as your guide “star” to locating Mercury closer to the horizon. Try viewing Mercury before sunrise for a few weeks, centered on Mercury’s greatest morning elongation on January 19 . Mercury is tricky. If you look too soon, Mercury will be lost in the twilight glare; if you look too late, it will have followed the sun beneath the horizon.

Watch for Mercury low in the sky, and near the sunrise point on the horizon, seeking for this hidden treasure around 90 to 60 minutes before sunrise. Remember, binoculars are always helpful for any Mercury search. Good Luck! For a big challenge, seek for the slender waning crescent moon pairing up with Mercury before sunrise on January 25 and 26 . Binoculars may come in handy! Click here for recommended almanacs; they can give you Mercury’s rising time in your sky . What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try. This image is from February 8, 2016.

It shows all 5 bright planets at once. Photo by our friend Eliot Herman in Tucson, Arizona. Bottom line: In January 2017, two of the five bright planets appear in the evening sky at dusk/nightfall: Venus and Mars. The other three planets – Jupiter, Saturn and Mercury – are found in the morning sky. Jupiter and the Moon Rendezvous Tonight: How to Watch Jupiter and the Moon Rendezvous Tonight: How to Watch By Joe Rao, SPACE.com Skywatching Columnist | October 25, 2013 12:28pm ET MORE Skywatcher Victor Rogus captured this shot of Jupiter and the moon near Jadwin, Missouri on Oct. 24, 2013. Credit: Victor Rogus If you are up late on this last Friday night (Oct. 25) in October — or during the predawn hours of Saturday (Oct. 26) — two objects will likely immediately catch your eye if the sky is clear: a waning gibbous moon and Jupiter.

The waning gibbous phase, which is 56 percent illuminated, will emerge from above the east-northeast horizon around 11:20 p.m. local daylight time. And shining brightly, roughly 7 degrees above it, will be the largest planet in our solar system, Jupiter . Your clenched fist measures about 10 degrees across at arm’s length, so the moon and Jupiter will be separated by roughly three-quarters of a fist. It is, of course, an illusion of perspective: the moon is only 248,000 miles (399,300 kilometers) from Earth. Meanwhile, Jupiter is 451 million miles (726 million km) away — over 1,800 times farther out in space compared with our natural satellite. [ Best Stargazing Events of October 2013 (Sky Map Gallery) ] Best views early in the morning Next to dazzling Venus , Jupiter is the best observer's planet during the fall and early winter. But Venus will quickly exit the evening sky early in January, leaving Jupiter unchallenged in the evening sky for the rest of the winter and on into early spring.

Look for Jupiter currently glimmering balefully above the east-northeast horizon by 11 p.m. local daylight time. But the gas giant will not reach an altitude of 30 degrees above the horizon — one-third of the way up in the sky — until 1:30 a.m. For some, that's considered to be the dividing line between objects that are "low" versus objects that are considered to be "well placed." Sharp telescopic views are seldom possible until an object reaches an altitude of 30 degrees, given the typical turbulent state of Earth's atmosphere. Soaring high Right now, Jupiter is in the constellation of Gemini, the Twins, near the star that marks the waist of the twin brother Pollux. Gemini is also where the ecliptic — the pathway of the sun, moon and planets — comes farthest north. This gives northern observers a decided advantage, for the farther north a planet is, the more time it spends above the horizon and the higher up over the southern part of the sky it will appear.

When Jupiter reaches its highest point in the southern sky, just after the first light of dawn twilight begins breaking over the eastern horizon, it will stand about 55 degrees high for Portland, Ore., and Minneapolis/St. Paul; 60 degrees for Salt Lake City and Philadelphia; 70 degrees for Houston and New Orleans and 75 degrees for Brownsville, Texas, and the Florida Keys. Two eclipses for the price of one Through a telescope, Jupiter is always a fascinating sight. Light and dark cloud belts in the giant planet's atmosphere appear to parallel the equator and slowly change, while the famous Great Red spot , some 30,000 mile (nearly 50,000 km) long, now appears rather pale and has been described with hues ranging from very pale beige to salmon pink. The other attractions are the four Galilean moons . During the overnight hours of late Friday night into Saturday morning, binoculars or a telescope will readily show all four of these big moons. Three will be on one side of Jupiter — Callisto (IV), Io (I) and Europa (II), with Ganymede (III) sitting by itself on the other side.

Interestingly, Io and Europa will appear relatively close to each other, and both will end up being eclipsed by Jupiter's shadow. Io will go first at 4:18 a.m. ET (1:18 a.m. PT). Nineteen minutes later, it will be Europa's turn. If you look at Jupiter anytime after that, you'll only see two of the remaining satellites, Callisto on one side, Ganymede on the other. Editor's note: If you snap an amazing photo of the moon and Jupiter, or any night sky view, that you'd like to share for a possible story or image gallery, please contact managing editor Tariq Malik at spacephotos@space.com . Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us @Spacedotcom , Facebook or Google+ . Originally published on SPACE.com.

JUPITER'S Moons - EnchantedLearning.com Jupiter's Moons Activities, Web Links JUPITER'S MOONS Jupiter has four large moons and dozens of smaller ones (there are about 67 known moons so far). Galileo first discovered the four largest moons of Jupiter, Io, Europa, Ganymede, and Callisto in 1610, using a 20-power telescope; these moons are known as the Galilean moons. The moons of Jupiter are (in order by their distance from Jupiter): Metis, Adrastea, Amalthea, Thebe, Io, Europa, Ganymede (the biggest), Callisto (the second biggest), Leda (the smallest), Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae, Sinope, and many newly-discovered moons that haven't been named yet. METIS Metis is the closest moon to Jupiter. Metis is 25 miles (40 km) in diameter and orbits 79,500 miles (128,000 km) from Jupiter, within its main ring.

Metis and the next moon, Adrastea, are probably the source of the dust in this ring. Metis has a mass of 9 x 1016kg. It orbits Jupiter in 0.294780 (Earth) days; this is faster than Jupiter rotates on its axis. Metis was discovered by Stephen Synnott (Voyager 2) in 1980. ADRASTEA Adrastea is the second-closest moon to Jupiter. Adrastea is 12 miles (20 km) in diameter and orbits 80,000 miles (129,000 km) from Jupiter, within its main ring. Adrastea and the first moon, Metis, are probably the source of the dust in this ring. Adrastea has a mass of 1.91 x 1016kg. It orbits Jupiter in 0.29826 (Earth) days; this is faster than Jupiter rotates on its axis. Adrastea was discovered by D. Jewitt and E. Danielson (Voyager 2) in 1979.

AMALTHEA Amalthea is the third-closest moon to Jupiter and the reddest object in our solar system . Amalthea is 145 x 91 x 83 miles (232 x146 x134 km) in diameter and orbits 112,700 miles (181,300 km) from Jupiter, within the faint Gossamer ring. Amalthea and Thebe likely provide the dust for the Gossamer ring. Amalthea has a mass of 7.2 x 1021kg. It orbits Jupiter in 0.49817905 (Earth) days and is in synchronous rotation (always keeping the same side facing Jupiter). Amalthea gives off more heat than it receives from the Sun. Amalthea was discovered by Edward Emerson Barnard in 1892. THEBE Thebe is the fourth-closest moon to Jupiter. Thebe is 68 x 56 miles (110 x 90 km) in diameter and orbits 138,000 miles (222,000 km) from Jupiter.

Amalthea and Thebe likely provide the dust for the Gossamer ring. Thebe has a mass of 8 x 1017kg. It orbits Jupiter in 0.6745 day (Earth) days and is in synchronous rotation (always keeping the same side facing Jupiter). Thebe was discovered by Stephen Synnott (Voyager 1) in 1980. THE GALILEAN MOONS Two sulfurous eruptions on Io. Pillan Patera, a volcanic caldera at the left, spews sulfur 86 miles above the surface. IO Io is a large, rocky, volcanically active moon of Jupiter. Its volcanoes spew out molten sulfur, making Io a very colorful moon. It is the innermost of Jupiter's four large moons and the third largest. It has a diameter of 1,942 miles (3,636 km), very close in size to our moon . Io's mean distance from Jupiter is 220,000 miles (422,000 km). It has a mass of 8.93x1022 kg.

It takes Io 1.77 days to orbit Jupiter. There is a doughnut-shaped plasma cloud around Jupiter near Io's orbit (known as the "Io plasma torus") This torus is caused by Jupiter's strong magnetic field, which strips ions from Io as it rotates; Io acts like an electrical generator. Io was discovered by Galileo and Marius (independently) in 1610. Ole Romer (1644-1710) was a Danish astronomer who, in 1675-1676, was the first person to demonstrate that the speed of light is finite. Romer did this by observing eclipses of Jupiter's moon Io as Jupiter's distance from Earth varied through the year. He noticed that the observed period of Io's orbit differed by about 20 minutes; he concluded that this difference was due to the extra distance that the light had to travel to Earth. His calculations put the speed of light at about 225,000 kilometers per second (it is really a bit faster, at 299,792 kilometers per second). EUROPA Europa is a large, dense, icy moon of Jupiter.

Europa is the smoothest object in our Solar System . Its surface is covered with long, crisscrossing trackways (but few craters) on water ice. Frozen sulfuric acid has been found on its surface. Europa's diameter is less than 2,000 miles (3,138 km), smaller than the Earth's moon . It takes Europa 3.55 days to orbit Jupiter (in a synchronous orbit). Its mean distance from Jupiter is about 420,000 miles (670,900 km). Its mass is 4.80x1022 kg. It was discovered by Galileo and S. Marius (independently) in 1610. GANYMEDE Ganymede is the largest moon of Jupiter, a large, icy, outer moon that is scarred with impact craters and many parallel faults. It has a diameter of about 3,400 miles (5,268 km) and orbits Jupiter at a mean distance of 664,000 miles (1,070,000 km). It has a magnetic field and probably has a molten iron core.

It takes Ganymede 171.75 hours (7.15 Earth days) to orbit Jupiter. Its mass is 1.48x1023 kg. It was discovered by Galileo and S. Marius (independently) in 1610. Ganymede is the largest moon in the solar system; it is also larger than the planets Mercury and Pluto. CALLISTO Callisto is a large, icy, dark-colored, low-density outer moon of Jupiter that is scarred with impact craters and ejecta. It has a diameter of about 3,000 miles (4800 km), the second-largest moon of Jupiter; it is roughly the size of Mercury . Callisto has the largest-known impact crater in the Solar System, Valhalla, which has a bright patch 600 km across and rings that go out to almost 3000 km. Callisto orbits Jupiter at a mean distance of 1,170,000 miles (1,883,000 km). Its mass is 1.08x1023 kg.

It takes Callisto 400.8 hours = 16.7 days to orbit Jupiter (in a synchronous orbit). Callisto was discovered by Galileo and S. Marius (independently) in 1610. LEDA Leda is Jupiter's ninth and smallest moon. Leda is 9.9 miles (16 km km) in diameter and orbits at an average of 6,900,000 miles (11,094,000 km) from Jupiter. Leda has a mass of 5.68 x 1015kg. It orbits Jupiter in 238.72 (Earth) days. Very little is known about Leda. Leda was discovered by Charles Kowal in 1974. HIMALIA Himalia is Jupiter's tenth moon. Himalia is 110 miles (170 km) in diameter and orbits 7,000,000 miles (11,480,000 km) from Jupiter. Himalia has a mass of 9.5 x 1018kg.

It orbits Jupiter in 250.5662 (Earth) days. Very little is known about Himalia. Himalia was discovered by C. Perrine in 1904. LYSITHEA Lysithea is Jupiter's eleventh moon. Lysithea is 15 miles (24 km) in diameter and orbits 7,200,000 miles (11,720,000 km) from Jupiter. Lysithea has a mass of 8 x 1016kg. It orbits Jupiter in 259.22 (Earth) days. Very little is known about Lysithea. Lysithea was discovered by S. Nicholson in 1938. ELARA Elara is Jupiter's twelfth moon. Elara is 50 miles (80 km) in diameter and orbits 7,250,000 miles (11,737,000 km) from Jupiter. Elara has a mass of 8 x 1017kg. It orbits Jupiter in 259.6528 (Earth) days.

Very little is known about Elara. Elara was discovered by C. Perrine in 1905. ANANKE Ananke is Jupiter's thirteenth moon. Ananke is 12.5 miles (20 km) in diameter and orbits 13,100,000 miles (21,200,000 km) from Jupiter. Ananke has a mass of 4 x 1016kg. It orbits Jupiter in 631 (Earth) days and is in a retrograde orbit (orbiting opposite to the direction of Jupiter). Very little is known about Ananke. Ananke was discovered by S. Nicholson in 1951. CARME Carme is Jupiter's fourteenth moon. Carme is 18.5 miles (30 km) in diameter and orbits 13,800,000 miles (22,600,000 km) from Jupiter. Carme has a mass of 9 x 1016kg. It orbits Jupiter in 692 (Earth) days and is in a retrograde orbit (orbiting opposite to the direction of Jupiter).

Very little is known about Carme. Carme was discovered by S. Nicholson in 1938. PASIPHAE Pasiphae is Jupiter's fifteenth moon. Pasiphae is 22 miles (36 km) in diameter and orbits 14,600,000 miles (23,500,000 km) from Jupiter. Pasiphae has a mass of 2 x 1023kg. It orbits Jupiter in 735 (Earth) days and is in a retrograde orbit (orbiting opposite to the direction of Jupiter). Very little is known about Pasiphae. Pasiphae was discovered by P. Melotte in 1908. SINOPE Sinope is Jupiter's sixteenth moon. Sinope is 17.5 miles (28 km) in diameter and orbits 14,700,000 miles (23,700,000 km) from Jupiter. Sinope has a mass of 8 x 1016kg.

It orbits Jupiter in 758 (Earth) days and is in a retrograde orbit (orbiting opposite to the direction of Jupiter). Very little is known about Sinope. Sinope was discovered by S. Nicholson in 1914. S/1999 J 1 (a provisional name) The seventeenth and outermost moon; S/1999 J 1 is the smallest-known moon orbiting a major planet. This moon is 3 miles (5 km) in diameter and has an irregular orbit roughly 15 million miles (24 million km) from Jupiter. It orbits Jupiter in 774 (Earth) days and is in a retrograde orbit (orbiting opposite to the direction of Jupiter). It was discovered by Robert S. McMillan et al (at the Spacewatch program at the University of Arizona ) in 2000. Mars Global Surveyor MOC2-368 Release Earth, Moon, and Jupiter, as Seen From Mars MGS MOC Release No.

MOC2-368, 22 May 2003 All Images Credit: NASA/JPL/Malin Space Science Systems View of Earth and Jupiter from Mars on May 8, 2003. Alignment of Earth and Jupiter as seen from Mars on May 8, 2003. North and South America were in view. All Images Credit: NASA/JPL/Malin Space Science Systems What does Earth look like when viewed from Mars? At 13:00 GMT on 8 May 2003, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) had an opportunity to find out. In addition, a fortuitous alignment of Earth and Jupiter---the first planetary conjunction viewed from another planet---permitted the MOC to acquire an image of both of these bodies and their larger satellites. At the time, Mars and the orbiting camera were 139 million kilometers (86 million miles) from Earth and almost 1 billion kilometers (nearly 600 million miles) from Jupiter. The orbit diagram, above, shows the geometry at the time the images were obtained.

Because Jupiter is over 5 times farther from the Sun than Earth, two different exposures were needed to image the two planets. Mosaiced together, the images are shown above (top picture). The composite has been highly contrast-enhanced and "colorized" to show both planets and their satellites. The MGS MOC high resolution camera only takes grayscale (black-and-white) images; the color was derived from Mariner 10 and Cassini pictures of Earth/Moon and Jupiter, respectively, as described in the note below. Earth/Moon: This is the first image of Earth ever taken from another planet that actually shows our home as a planetary disk. Because Earth and the Moon are closer to the Sun than Mars, they exhibit phases, just as the Moon, Venus, and Mercury do when viewed from Earth. As seen from Mars by MGS on 8 May 2003 at 13:00 GMT (6:00 AM PDT), Earth and the Moon appeared in the evening sky. The MOC Earth/Moon image has been specially processed to allow both Earth (with an apparent magnitude of -2.5) and the much darker Moon (with an apparent magnitude of +0.9) to be visible together.

The bright area at the top of the image of Earth is cloud cover over central and eastern North America. Below that, a darker area includes Central America and the Gulf of Mexico. The bright feature near the center-right of the crescent Earth consists of clouds over northern South America. The image also shows the Earth-facing hemisphere of the Moon, since the Moon was on the far side of Earth as viewed from Mars. The slightly lighter tone of the lower portion of the image of the Moon results from the large and conspicuous ray system associated with the crater Tycho. Jupiter/Galilean Satellites: When Galileo first turned his telescope toward Jupiter four centuries ago, he saw that the giant planet had four large satellites, or moons. These, the largest of dozens of moons that orbit Jupiter, later became known as the Galilean satellites. The larger two, Callisto and Ganymede, are roughly the size of the planet Mercury; the smallest, Io and Europa, are approximately the size of Earth's Moon. This MGS MOC image, obtained from Mars orbit on 8 May 2003, shows Jupiter and three of the four Galilean satellites: Callisto, Ganymede, and Europa.

At the time, Io was behind Jupiter as seen from Mars, and Jupiter's giant red spot had rotated out of view. This image has been specially processed to show both Jupiter and its satellites, since Jupiter, at an apparent magnitude of -1.8, was much brighter than the three satellites. A note about the coloring process: The MGS MOC high resolution camera only takes grayscale (black-and-white) images. To "colorize" the image, a Mariner 10 Earth/Moon image taken in 1973 was used to color the MOC Earth and Moon picture, and a recent Cassini image acquired during its Jupiter flyby was used to color the MOC Jupiter picture. The procedure used was as follows: the Mariner 10 and Cassini color images were converted from 24-bit color to 8-bit color using a JPEG to GIF conversion program. These 8-bit color images were converted to 8-bit grayscale and an associated lookup table mapping each gray value of that image to a red-green-blue color triplet (RGB). Each color triplet was root-sum-squared (RSS), and sorted in increasing RSS value. These sorted lists were brightness-to-color maps for their respective images.

Each brightness-to-color map was then used to convert the 8-bit grayscale MOC image to an 8-bit color image. This 8-bit color image was then converted to a 24-bit color image. The color image was edited to return the background to black. Three separate color tables were used: one each for the Earth, Moon and Jupiter. Jupiter's Galilean Satellites were not colored. To view the unprocessed Earth/Moon image, download the following to your desktop and view with your favorite image viewing or processing tool: R05-00763.gif . To view the unprocessed Jupiter image, download the following to your desktop and view with your favorite image viewing or processing tool: R05-00762.gif . Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.

Ganymede: Facts About Jupiter's Largest Moon Ganymede: Facts About Jupiter's Largest Moon By Kim Zimmermann | June 15, 2016 10:53am ET MORE NASA's Voyager 2 spacecraft snapped this color image of Jupiter's moon Ganymede, the largest satellite in the solar system, on July 7, 1979 from a distance of 745,000 miles (1.2 million kilometers). Credit: NASA Jupiter's moon Ganymede is the largest satellite in the solar system. Larger than Mercury and Pluto, and only slightly smaller than Mars, it would easily be classified as a planet if were orbiting the sun rather than Jupiter. The moon likely has a salty ocean underneath its icy surface, making it a potential location for life. The European Space Agency plans a mission to Jupiter's icy moons that in 2030, is planned to arrive and put special emphasis on observing Ganymede. Facts about Ganymede Age: Ganymede is about 4.5 billion years old, about the same age as Jupiter .

Distance from Jupiter: Ganymede is the seventh moon and third Galilean satellite outward from Jupiter, orbiting at about 665,000 miles (1.070 million kilometers). It takes Ganymede about seven Earth-days to orbit Jupiter. [ Photos of Ganymede, Jupiter's Largest Moon ] Size: Ganymede's mean radius is 1,635 miles (2,631.2 km). Although Ganymede is larger than Mercury it only has half its mass, classifying it as low density. Temperature: Daytime temperatures on the surface average minus 171 degrees Fahrenheit to minus 297 F, and night temperatures drop to -193C. In 1996, astronomers using the Hubble Space Telescope found evidence of a thin oxygen atmosphere. However, it is too thin to support life as we know it; it is unlikely that any living organisms inhabit Ganymede. Magnetosphere: Ganymede is the only satellite in the solar system to have a magnetosphere. Typically found in planets, including Earth and Jupiter, a magnetosphere is a comet-shaped region in which charged particles are trapped or deflected.

Ganymede's magnetosphere is entirely embedded within the magnetosphere of Jupiter. This montage compares New Horizons' best views of Ganymede, Jupiter's largest moon, gathered with the spacecraft's Long Range Reconnaissance Imager (LORRI) and its infrared spectrometer, the Linear Etalon Imaging Spectral Array (LEISA). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute Discovery and exploration of Ganymede Ganymede was discovered by Galileo Galilei on Jan. 7, 1610. The discovery, along with three other Jovian moons , was the first time a moon was discovered orbiting a planet other than Earth. Galileo's discovery eventually led to the understanding that planets orbit the sun, instead of our solar system revolving around Earth. Galileo called this moon Jupiter III. When the numerical naming system was abandoned in the mid-1800s, the moon was named after Ganymede, a Trojan prince in Greek mythology. Zeus, a counterpart of Jupiter in Roman mythology, carried Ganymede, who had taken the form of an eagle, to Olympus, where he became a cupbearer to the Olympian gods and one of Zeus' lovers.

Several spacecraft have flown by Jupiter and its moons. Pioneer 10 arrived first, in 1973, followed by Pioneer 11 in 1974. Voyager 1 and Voyager 2 returned striking photos during their flybys. The Galileo spacecraft passed as low as 162 miles (261 km) over the surfaces of the Galilean moons and produced detailed images. The European Space Agency plans a mission called JUICE (JUpiter ICy moons Explorer) that would launch from Earth in 2022 for arrival at Jupiter in 2030. While the mission will look at three moons (Ganymede, Callisto and Europa), Ganymede will be the focus because it shows how icy worlds evolve and could be habitable in general, ESA said on its website. Scientists will try to figure out more about its ocean and icy crust, map its surface in detail, learn about the interior, probe the atmosphere and study the magnetic field.

Ganymede sound and signal illustration Characteristics of Ganymede Ganymede has a core of metallic iron, which is followed by a layer of rock that is topped off by a crust of mostly ice that is very thick. There are also a number of bumps on Ganymede's surface, which may be rock formations. In February 2014, NASA and the United States Geological Survey unveiled the first detailed map of Ganymede in images and a video animation created using observations from NASA's Voyager 1 and Voyager 2 spacecraft, as well as the dedicated Jupiter-orbiting Galileo spacecraft. Ganymede's surface is made up of primarily two types of terrain: about 40 percent is dark with numerous craters, and 60 percent is lighter in color with grooves that form intricate patterns to give the satellite its distinctive appearance. The grooves, which were likely formed as a result of tectonic activity or water being released from beneath the surface, are as high as 2,000 feet and stretch for thousands of miles. A global image mosaic of Jupiter's moon, Ganymede created with images from the Voyager and Galileo missions.

Credit: Wes Patterson It is believed that Ganymede has a saltwater ocean below its surface. In 2015, a study by the Hubble Space Telescope looked at Ganymede's auroras and how they change between Ganymede's and Jupiter's magnetic fields. The “rocking” seen by the auroras gives evidence that the probable ocean underneath is salty , more salty than oceans of Earth, scientists said at the time. Some scientists are skeptical that Ganymede could host life, however. Due to its internal structure, it is believed that the pressure at the base of the ocean is so high that any water down there would turn to ice . This would make it difficult for any hot-water vents to bring nutrients into the ocean, which is one scenario under which scientists believe extraterrestrial life would occur. Additional reporting by contributor Elizabeth Howell. Additional resource

Question: Which moon of Jupiter is roughly three-quarters of the size of Mars?
Answer: Ganymede