Blog Archives

This Was Rosetta’s View of Earth and the Moon in March 2005

The Moon beyond Earth's limb imaged by ESA's Rosetta spacecraft on March 4, 2005 (ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0)

The Moon beyond Earth’s limb imaged by ESA’s Rosetta spacecraft on March 4, 2005 (ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0)

ESA’s comet-chasing Rosetta mission is best known today for its two historic firsts of entering orbit around a comet and sending a lander onto the surface of said comet, in May and November of 2014 respectively. But Rosetta didn’t just go directly from its March 2, 2004 launch to comet 67P; it had to perform several flyby maneuvers beforehand with planets and asteroids on its way out to meet a comet. And now, ESA has shared many of the images acquired during those close passes during its cruise phase in a series of online albums for the public to easily access.

The image above shows the Moon beyond the hazy line of Earth’s atmosphere, acquired on March 4, 2005 during Rosetta’s first gravity-assist flyby of Earth just over a year after its launch. (Rosetta made three such passes by our planet before gathering enough velocity to make it out to 67P!)

See a list of Rosetta’s flybys below and find out how to access the albums.

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A Northern View of Saturn’s Stained Moon Iapetus

Saturn's moon Iapetus, imaged by Cassini on March 31, 2015 (NASA/JPL-Caltech/SSI)

Saturn’s moon Iapetus, imaged by Cassini on March 31, 2015 (NASA/JPL-Caltech/SSI)

Here’s a raw image of Saturn’s moon Iapetus, looking down on its northern hemisphere from Cassini on March 31, 2015. The moon’s signature two-toned coloration is evident as its bright icy surface is partially coated by dark material, thought to have been ejected from distant neighbor Phoebe.

Iapetus is 914 miles (1,471 km) in diameter, or about as wide as Texas and Louisiana combined. It orbits Saturn at a considerable distance of 2,212,889 miles (3,561,300 km), which is nine times farther than the Moon is from us.

Iapetus’ north pole is located just below and to the left of the centrally-peaked crater south of the brightest region in the image above. (The two prominent craters near image center are Roland and Turpin.)

Learn more about Iapetus here, and for a color version of the above image click here.

Cassini Captures Narrow-Angle, Wide-Spectrum Views of Rhea

Composite image of Saturn's moon Rhea from Feb. 9, 2015. Credit: NASA/JPL-Caltech/SSI.

Composite image of Saturn’s moon Rhea from Feb. 9, 2015. Credit: NASA/JPL-Caltech/SSI.

After spending a couple of years in an orbit riding high over the northern pole of Saturn Cassini has swung back down alongside the planet’s ringplane, in perfect alignment to once again capture views of the icy moons that reside there. The image above is a composite made from several narrow-angle camera images acquired by Cassini on Feb. 9, 2015, showing an extended color view of Rhea as the spacecraft was heading to perform a targeted flyby of the larger haze-covered moon Titan.

Saturn’s second-largest moon, the heavily-cratered Rhea wouldn’t appear this golden to our eyes; its natural colors are much more monochromatic (i.e., grey.) But Cassini can “see” in light stretching from ultraviolet to infrared, and that added range lets us see Rhea in a new light.

Read the rest of this article on Discovery News here.

Ganymede’s Aurorae Hint at an Ocean Ten Times Deeper than Earth’s

Illustration of Ganymede's auroral ovals, the stability of which hint at a global underground ocean. Credit: NASA, ESA, and G. Bacon (STScI).

Illustration of Ganymede’s auroral ovals, the stability of which hint at a global underground ocean. Credit: NASA, ESA, and G. Bacon (STScI).

It’s long been suspected that Jupiter’s giant moon Ganymede may harbor a subsurface ocean of liquid water beneath its icy yet hard-as-rock crust, and now some ingenious observations with the Hubble Space Telescope are making an even more convincing case for it!

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When a Comet Met Ganymede

Galileo image of a crater chain on Jupiter's moon Ganymede (NASA/JPL)

Galileo image of a crater chain on Jupiter’s moon Ganymede (NASA/JPL)

Captured by NASA’s Galileo spacecraft on April 5, 1997, this image shows Enki Catena, a 161.3-km (100-mile) long crater chain on the surface of Jupiter’s moon Ganymede. Named after the Sumerian god of fresh water, Enki Catena is thought to have been formed when a comet approached too close to Jupiter and was torn into 13 pieces, each impacting Ganymede in rapid succession… sort of a miniature version of what occurred in 1994 with comet Shoemaker-Levy 9.

Ganymede is not only Jupiter’s largest moon but also the largest moon in the Solar System. At 5,268 km (3,273 miles) across it is larger than Pluto and Mercury, and is the only moon that generates its own magnetosphere.

Launched in October 1989, Galileo arrived at Jupiter in December 1995 and orbited the giant planet 34 times before ending its mission with a dive into Jupiter’s atmosphere on September 21, 2003. Learn more about Galileo mission highlights here.


Oh What a Relief! Cool 3D Views of the Moon via LROC

Red/cyan anaglyph of Hell Q crater on the Moon's near side  (NASA/GSFC/Arizona State University)

Red/blue anaglyph of Hell Q crater on the Moon’s near side (NASA/GSFC/Arizona State University)

Do you have any of those paper 3D viewers around? You know, with the red and blue lenses? If so, pop ’em on and check out the image above from NASA’s Lunar Reconnaissance Orbiter Camera (LROC) showing the crater “Hell Q,” located on the Moon’s southern near side near the brightly-rayed Tycho. You might think a crater was just carved into your screen!

The 3.75-km-wide Hell Q is one of a cluster of 19 craters located around the main 32.5-km Hell crater. (And no, it wasn’t named after a realm of the afterworld but rather for Hungarian astronomer Maximillian Hell.)

The image was acquired on April 11, 2014. You can see a larger 3D view of the region around Hell Q below.

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