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Rosetta’s Comet Looks Like a Giant Peep

Video of Comet 67P/Churyumov-Gerasimenko made from images acquired by the approaching Rosetta on July 14, 2014.

Video of Comet 67P/Churyumov-Gerasimenko’s nucleus made from images acquired by the approaching Rosetta on July 14, 2014.

Surprise!* Rosetta’s target comet 67P/C-G is apparently a contact binary, with a nucleus made of two objects joined at a point and held together by gravity based on the latest images in from the spacecraft. Tumbling through space on its orbit around the Sun, it bears an uncanny resemblance to… a giant marshmallow Peep. (The chick kind, not the bunny.)

At nearly 4 km across at its longest dimension, that’s one big Peep!

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Venus Express Survived Its Dive!

Illustration of ESA's Venus Express aerobraking in Venus' upper atmosphere (ESA)

Illustration of ESA’s Venus Express aerobraking in Venus’ upper atmosphere (ESA)

Having made over 3,000 orbits of Venus over the past eight years, ESA’s Venus Express has (as of May 15) completed its science mission and is now in the final few months of its operational life. With a nothing-left-to-lose attitude, the spacecraft recently made a daring and risky dive down into the upper layers of the planet’s thick atmosphere, coming within 80 miles of Venus’ broiling surface on July 12 — that’s the closest any human-made spacecraft have gotten to Venus since the Soviet Vega balloon-and-lander missions of 1985!

As dangerous as it may have been for the spacecraft, Venus Express survived the encounter and grabbed some valuable data about the planet’s atmosphere along the way. It’s now working its way up to a higher altitude orbit, but there’s no escaping the fact that its fuel reserves are nearly depleted and it will soon be back on its way down into Venus’ atmosphere on a mission-ending, one-way trip.

Read the rest of my article on Discovery News here.

Cassini Marks Ten Discovery-Filled Years at Saturn

Cassini by the Numbers: an infographic of the spacecraft's achievements over the past decade (NASA/JPL-Caltech)

Cassini by the Numbers: an infographic of the spacecraft’s achievements over the past decade (NASA/JPL-Caltech)

Just a week after Curiosity celebrated its first Martian year in Gale Crater and we have yet another milestone anniversary in Solar System exploration: as of 10:48 p.m. EDT tonight Cassini will have been in orbit around Saturn for a full decade!

“There are times when human language is inadequate, when emotions choke the mind, when the magnitude of events cannot properly be conveyed by the same syllables we use to navigate everyday life. The evening of June 30, 2004 was such a time.” 

– Carolyn Porco, Cassini Imaging Team Leader, CICLOPS “Captain’s Log” on June 30, 2014

That’s ten years and over 2 billion miles of discoveries and explorations of our Solar System’s most majestic planet and its incredibly varied family of moons. Over the course of its primary mission and three extended missions, we have been able to get a close-up look at Saturn and its moons like never before, witnessing first-hand the changes that occur as their seasons change. What’s been discovered by the Cassini mission about Saturn has offered invaluable insight into the evolution of our entire Solar System, as well as planets that could be found elsewhere in our galaxy.

“Having a healthy, long-lived spacecraft at Saturn has afforded us a precious opportunity,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “By having a decade there with Cassini, we have been privileged to witness never-before-seen events that are changing our understanding of how planetary systems form and what conditions might lead to habitats for life.”

Launched on October 15, 1997, the Cassini-Huygens spacecraft established orbit around Saturn on June 30, 2004 (July 1, UTC).

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Hubble Spots Saturn’s Northern Lights

Hubble image of aurora on Saturn (NASA/ESA)

Hubble image of aurora on Saturn (NASA/ESA)

Earth isn’t the only planet with auroras — any world with a magnetic field and an atmosphere can get a light show around its poles when its star’s wind is blowing hard enough!* The image above shows Saturn’s northern lights, as seen in ultraviolet light by the Hubble Space Telescope’s Advanced Camera for Surveys in April 2013.

See the full lineup of images below:

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This is How Saturn’s Rings Would Look to a Butterfly

Ultraviolet image of Saturn's rings acquired by Cassini in 2004 (NASA/JPL-Caltech/University of Boulder)

Ultraviolet image of Saturn’s rings acquired by Cassini in 2004 (NASA/JPL-Caltech/University of Boulder)

You don’t typically see Saturn’s rings looking like this, but then you can’t see in ultraviolet like Cassini (or many insects) can! The image above was acquired by the UVIS (UltraViolet Imaging Spectrograph) instrument aboard the Cassini-Huygens spacecraft on June 30, 2004, just as it was entering orbit around Saturn.

The area shown here is about 10,000 km (6,200 miles) across. It’s a small section of ring segments… just a portion of Saturn’s magnificent expanse of rings. Part of the C ring, toward Saturn, is along the left, and the inner edge of the B ring begins just right of the center. The colors are related to the composition of the ring particles; blue and green colors are from bright water ice, reds are rings with darker, “dirtier” particles.

While the colors aren’t “real” per se — our eyes simply can’t see UV light — the association of colors we can see to specific UV wavelengths allows scientists to accurately observe relative differences in the ring segments.

“It is cool that we can pick our own colors in the pictures we produce,” said Dr. Larry W. Esposito, a professor of Astrophysical and Planetary Sciences at the University of Colorado and UVIS Principal Investigator. “No person has ever seen ultraviolet light, although some butterflies can. Our pictures may thus represent a ‘butterfly’s-eye view’ of the Saturn system.”

Click the image to access a higher-resolution image on ESA’s Flickr page, and read more about the Cassini mission here.

The Glory of Venus

A rainbow-colored "glory" in Venus' atmosphere seen by ESA's Venus Express

A rainbow-colored “glory” in Venus’ atmosphere seen by ESA’s Venus Express

Oh, glorious Venus! How fragrant are your sulphuric skies! How your rainbow clouds do shimmer!

Actually the sulfuric acid-laden clouds of our neighboring planet would be anything but pleasant for humans, but ESA’s Venus Express orbiter did spot some iridescent hues as it flew over. The picture above, made from images acquired on July 24, 2011, show a circular “rainbow” effect known as a glory. It’s the backscattering of sunlight observed around the shadow point of an object when the Sun is directly behind it from the perspective of the observer (in this case, Venus Express itself.)

Glories are often seen here on Earth from aircraft (but sometimes even from the ground within banks of dense fog) and the mechanics of this one on Venus are pretty much the same — except that the composition of Venus’ clouds is very different, leading to a perfect opportunity for science! Read more…

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A Ceres of Surprises: the Largest Asteroid is a Water World

Artist's interpretation of Ceres, the largest object in the main asteroid belt. (NASA/JPL-Caltech)

Artist’s interpretation of Ceres, the largest object in the main asteroid belt. (NASA/JPL-Caltech)

By now you must know about the jets of ice particles blasting out of Saturn’s moon Enceladus, and maybe have even heard about the recent discovery of water vapor issuing forth from Jupiter’s frozen moon Europa. But now we know of another spray-happy world out there: Ceres, which at 591 miles across is our solar system’s smallest dwarf planet but the largest object in the  asteroid belt. New findings from ESA’s Herschel Space Observatory reveal that this diminutive world is jetting water vapor out into space, proving both that it has an icy surface and that water does in fact exist in the main asteroid belt, which stretches out between the orbits of Mars and Jupiter. Read more below: Read the rest of this entry

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