Solar System Archives

February 11, 2013April 26, 2016 by Jason Major

Help Name Pluto’s Newest Moons!

Pluto's known system of moons (NASA/ESA/M. Showalter))

Today marks seven months since the announcement of Pluto’s fifth moon and over a year and a half since the discovery of the one before that. But both moons still have letter-and-number designations, P5 and P4, respectively… not very imaginative, to say the least, and not really fitting into the pantheon of mythologically-named worlds in our Solar System.

Today, you can help change that.

According to the New Horizons research team, after the discovery of P4 in June 2011 it was decided to wait to see if any more moons were discovered in order to choose names that fit together as a pair, while a*lso following accepted IAU naming practices. Now, seven months after the announcement of P5, we think a decision is in order… and so does the P4/P5 Discovery Team at the SETI Institute.

"Hey, I can be democratic about this!" — “Hey, I can be democratic about all this!”

Today, SETI Senior Research Scientist Mark Showalter revealed a new poll site, Pluto Rocks, where visitors can place their votes on a selection of names for P4 and P5 — or even write in a suggestion of their own. In line with IAU convention these names are associated with the Greek and Roman mythology surrounding Pluto/Hades and his underworld-dwelling minions.

“In 1930, a little girl named Venetia Burney suggested that Clyde Tombaugh name his newly discovered planet ‘Pluto.’ Tombaugh liked the idea and the name stuck. I like to think that we are doing honor to Tombaugh’s legacy by now opening up the naming of Pluto’s two tiniest known moons to everyone.”

– Mark Showalter, SETI Institute

As of the time of this writing, the ongoing results look like this:

Results of Pluto Rocks voting as of Feb. 11, 2013 at 10 am EST (15:00 UT)

Do you like where the voting is headed? Are you hellishly opposed? Go place your vote now and make your opinion count in the naming of these two distant worlds!

(After all, New Horizons will be visiting Pluto in just under two and a half years, and she really should know how to greet the family.)

Voting ends at noon EST on Monday, February 25th, 2013.

The SETI team welcomes you to submit your vote every day, but only once per day so that voting is fair.

UPDATE: On Feb. 25, the final day of voting, the tally is looking like this:

PlutoRocks results as of Feb. 25, 2013 - Vulcan is in the lead, thanks to publicity from Mr. William Shatner — PlutoRocks results as of Feb. 25, 2013 – Vulcan is in the lead, thanks to publicity from Mr. William Shatner

Thanks in no small part to a bit of publicity on Twitter by Captain Kirk himself, Mr. William Shatner (and support by Leonard Nimoy) “Vulcan” has made the list and warped straight to the lead. Will SETI and the IAU honor such Trek fan support with an official designation? We shall soon find out…

January 24, 2013December 23, 2015 by Jason Major

27 Years Ago: Voyager 2’s Visit to Uranus

Image of Uranus’ crescent taken by a departing Voyager 2 on January 25, 1986 (NASA/JPL)

27 years ago today, January 24, 1986, NASA’s Voyager 2 spacecraft sped past Uranus, becoming simultaneously the first and last spacecraft to visit the blue-tinged gas giant, third largest planet in the Solar System.

The image above shows the crescent-lit Uranus as seen by Voyager 2 from a distance of about 965,000 km (600,000 miles.) At the time the spacecraft had already passed Uranus and was looking back at the planet on its way outwards toward Neptune.

Although composed primarily of hydrogen and helium, trace amounts of methane in Uranus’ uppermost atmosphere absorb most of the red wavelengths of light, making the planet appear a pale blue color.

Image of the 1,500-km-wide Oberon acquired by Voyager 2 on Jan. 24, 1986 (NASA/JPL)

The second of NASA’s twin space explorers (although it launched first) Voyager 2 came within 81,800 kilometers (50,600 miles) of Uranus on January 24, 1986, gathering images of the sideways planet, its rings and several of its moons. Voyager 2 also discovered the presence of a magnetic field around Uranus, as well as 10 new small moons.

Three moons discovered by Voyager 2 in 1986 (NASA/JPL)

Data gathered by Voyager 2 revealed that Uranus’ rate of rotation is 17 hours, 14 minutes.

At the time of this writing, Voyager 2 is 15,184,370,900 km from Earth and steadily moving toward the edge of the Solar System at a speed of about 3.3 AU per year. At that distance, signals from Voyager take just over 14 hours and 4 minutes to reach us.

See images from Voyager 2’s visit of Uranus here, and check out a video of the August 20, 1977 launch below along with more images from the historic Voyager mission’s “Grand Tour” of the outer Solar System.

January 21, 2013December 23, 2015 by Jason Major

Take a Rollercoaster Ride Around Venus

If you’ve ever wanted to see what it’s like to buzz Venus like only a spacecraft can, here’s your chance: this is a video animation of images taken by ESA’s Venus Express as it makes a pole-to-pole orbit of our neighboring world.

Captured in ultraviolet wavelengths, the images were acquired by the spacecraft’s Venus Monitoring Camera last January over a period of 18 hours. It’s truly a “day in the life” of Venus Express!

From ESA’s description of the video:

We join the spacecraft from a staggering 66,000 km above the south pole, staring down into the swirling south polar vortex. From this bird’s-eye view, half of the planet is in darkness, the ‘terminator’ marking the dividing line between the day and night sides of the planet.

Intricate features on smaller and smaller scales are revealed as Venus Express dives to just 250 km above the north pole and clouds flood the field of view, before regaining a global perspective as it climbs away from the north pole.

The observed pattern of bright and dark markings is caused by variations in an unknown absorbing chemical at the Venus cloud tops.

False-color image of cloud features on Venus. Captured by Venus Express from a distance of 30,000 km (18,640 miles) on December 8, 2011. (ESA/MPS/DLR/IDA)

Source: European Space Agency

January 15, 2013December 23, 2015 by Jason Major

A Hi-Res Mosaic of Mercury’s Crescent

A view of Mercury from MESSENGER’s October 2008 flyby (NASA / JHUAPL / Gordan Ugarkovic)

Every now and then a new gem of a color-composite appears in the Flickr photostream of Gordan Ugarkovic, and this one is the latest to materialize.

This is a view of Mercury as seen by NASA’s MESSENGER spacecraft during a flyby in October 2008. The image is a composite of twenty separate frames acquired with MESSENGER’s narrow-angle camera from distances ranging from 18,900 to 17,700 kilometers and colorized with color data from the spacecraft’s wide-angle camera. (North is to the right.)

Click the image for a closer look, and for an even bigger planet-sized version click here. Beautiful!

The images that made up this mosaic were taken two and a half years before MESSENGER entered orbit around Mercury on March 19, 2011 UT, becoming the first spacecraft ever to do so and making Mercury the final “classical” planet to be orbited by a manmade spacecraft.

Since that time MESSENGER has completed well over 1,000 orbits and taken more than 100,000 images of the first planet in the Solar System, which filled in most of our gaps in Mercury’s map and showed us many never-before-seen features of the planet’s Sun-scoured surface. And just this past year MESSENGER’s extended mission helped confirm what could be called its most important discovery of all: water ice on Mercury’s north pole.

This was even selected by Scientific American as one of the Top 5 Space Stories of 2012.

With all that’s been achieved by MESSENGER in 2011 and 2012, 2013 is looking to be an interesting year!

“We learned a great deal about Mercury over the past year,” said MESSENGER Principal Investigator Sean Solomon of Columbia University’s Lamont-Doherty Earth Observatory. “The team published three dozen scientific and technical papers and delivered more than 150 presentations at national and international meetings. New measurements continue to stream back from our spacecraft, and we can look forward with excitement to many additional discoveries in 2013.”

Follow the MESSENGER mission news here and see more of Gordan’s space images here.

Inset image: 12 Mercurial discoveries by MESSENGER in 2012. Click to review.

January 10, 2013December 23, 2015 by Jason Major

What Craters on the Moon Teach Us About Earth

When the Moon was receiving its highest number of impacts, so was Earth. Credit: Dan Durda

Some questions about our own planet are best answered by looking someplace else entirely… in the case of impact craters and when, how and how often they were formed, that someplace can be found shining down on us nearly every night: our own companion in space, the Moon.

By studying lunar impact craters both young and old scientists can piece together the physical processes that took place during the violent moments of their creation, as well as determine how often Earth — a considerably bigger target — was experiencing similar events (and likely in much larger numbers as well.)

With no substantial atmosphere, no weather and no tectonic activity, the surface of the Moon is a veritable time capsule for events taking place in our region of the Solar System. While our constantly-evolving Earth tends to hide its past, the Moon gives up its secrets much more readily… which is why present and future lunar missions are so important to science.

Take the crater Linné, for example. A young, pristine lunar crater, the 2.2-km-wide Linné was formed less than 10 million years ago… much longer than humans have walked the Earth, yes, but very recently on lunar geologic terms.

It was once thought that the circular Linné (as well as other craters) is bowl-shaped, thus setting a precedent for the morphology of craters on the Moon and on Earth. But laser-mapping observations by NASA’s Lunar Reconnaissance Orbiter (at right) determined in early 2012 that that’s not the case; Linné is actually more of a truncated inverted cone, with a flattened interior floor surrounded by sloping walls that rise up over half a kilometer to its rim.

On our planet the erosive processes of wind, water, and earth soon distort the shapes of craters like Linné, wearing them down, filling them in and eventually hiding them from plain sight completely. But in the Moon’s airless environment where the only weathering comes from more impacts they retain their shape for much longer lengths of time, looking brand-new for many millions of years. By studying young craters in greater detail scientists are now able to better figure out just what happens when large objects strike the surface of worlds — events that can and do occur quite regularly in the Solar System, and which may have even allowed life to gain a foothold on Earth.

Most of the craters visible on the Moon today — Linné excluded, of course — are thought to have formed within a narrow period of time between 3.8 and 3.9 billion years ago. This period, called the Late Heavy Bombardment, saw a high rate of impact events throughout the inner Solar System, not only on the Moon but also on Mars, Mercury, presumably Venus and Earth as well. In fact, since at 4 times its diameter the Earth is a much larger target than the Moon, it stands to reason that Earth was impacted many more times than the Moon as well. Such large amounts of impacts introduced material from the outer Solar System to the early Earth as well as melted areas of the surface, releasing compounds like water that had been locked up in the crust… and even creating the sorts of environments where life could have begun to develop and thrive.

(It’s been suggested that there was even a longer period of heavy impact rates nicknamed the “late late heavy bombardment” that lingered up until about 2.5 billion years ago. Read more here.)

In the video below lunar geologist David Kring discusses the importance of impacts on the evolution of the Moon, Earth and eventually life as we know it today:

“Impact cratering in Earth’s past has affected not only the geologic but the biologic evolution of our planet, and we were able to deduce that in part by the lessons we learned by studying the Moon… and you just have to wonder what other things we can learn by going back to the Moon and studying that planetary body further.”

– David Kring

David is a senior staff scientist at the Lunar and Planetary Institute in Houston, TX.

It’s these sorts of connections that make lunar exploration so valuable. Keys to our planet’s past are literally sitting on the surface of the Moon, a mere 385,000 km away, waiting for us to just scoop them up and bring them back. While the hunt for a biological history on Mars or resource-mining an asteroid are definitely important goals in their own right, only the Moon holds such direct references to Earth. It’s like an orbiting index to the ongoing story of our planet — all we have to do is make the connections.

Learn more about lunar research at the LPI site here, and see the latest news and images from LRO here.

January 7, 2013December 23, 2015 by Jason Major

Kepler Finds Hundreds of New Exoplanet Candidates

Artist’s depiction of the Kepler 10 system, which contains planets 2.2 and 1.4 times the size of Earth. (NASA/Ames/JPL-Caltech)

Kepler mission scientists announced today the discovery of literally hundreds of new exoplanet candidates — 461, to be exact — orbiting distant stars within a relatively small cross-section of our galaxy, bringing the total number of potential planets awaiting confirmation to 2,740. What’s more, at least 4 of these new candidates appear to be fairly Earth-sized worlds located within their stars’ habitable zone, the orbital “sweet spot” where surface water could exist as a liquid.

Impressive results, considering that NASA’s planet-hunting spacecraft was launched a little under 4 years ago (and watching 150,000 stars to spot the shadows of planets is no easy task!)

“… the ways by which men arrive at knowledge of the celestial things are hardly less wonderful than the nature of these things themselves.”

— Johannes Kepler

Since the last official announcement of Kepler candidates in Feb. 2012 the number of smaller Earth- and super-Earth-sized worlds observed has risen considerably, as well as the identification of multi-planet systems that are organized more-or-less along a flat plane… just like ours.

“There is no better way to kickoff the start of the Kepler extended mission,” said Kepler scientist Christopher Burke, “than to discover more possible outposts on the frontier of potentially life bearing worlds.”

From the NASA press release:

Since the last Kepler catalog was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars. The most dramatic increases are seen in the number of Earth-size and super Earth-size candidates discovered, which grew by 43 and 21 percent respectively.

The new data increases the number of stars discovered to have more than one planet candidate from 365 to 467. Today, 43 percent of Kepler’s planet candidates are observed to have neighbor planets.

The most dramatic increases are seen in the number of Earth-size and super Earth-size candidates discovered, which grew by 43 and 21 percent respectively. (NASA)

Although some of the new candidates announced today are large Neptune-sized planets, more than half are Earth- to super-Earth sized worlds less than twice the radius of our own planet.

In order for Kepler candidates to be “officially” called exoplanets, they must be observed 3 times on a regular orbit — that is, their signature dimming of the light from their home star must occur as predicted once their presence and then orbital period is calculated. Only then is an exoplanet confirmed.

To date Kepler has confirmed 105 exoplanets.

The longer the mission continues, the better the chance that Kepler will be able to confirm smaller Earth-sized worlds in longer-period orbits.

“The analysis of increasingly longer time periods of Kepler data uncovers smaller planets in longer period orbits — orbital periods similar to Earth’s,” said Steve Howell, Kepler mission scientist. “It is no longer a question of will we find a true Earth analogue, but a question of when.”

Scientists analyzed more than 13,000 transit-like signals called ‘threshold crossing events’ to eliminate known spacecraft instrumentation and astrophysical false positives, phenomena that masquerade as planetary candidates, to identify the potential new planets. Watch the video below to see how Kepler observes the light-curve of transit events.

Read more on the NASA press release, and learn more about the Kepler mission here.

January 4, 2013December 23, 2015 by Jason Major

Ancient Impacts Stained Vesta with Carbon-Rich Material

Composite-color 3D image of Cornelia crater on Vesta (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Ever since arriving at Vesta in July 2011, NASA’s Dawn spacecraft has been capturing high-resolution images of the protoplanet’s surface, revealing a surprisingly varied and complex terrain covered in ridges, hills, grooves and, of course, craters of many different sizes and ages. Many of Vesta’s largest craters exhibit strange dark stains and splotches within and around them, some literally darker than coal. These stains were a puzzle to scientists when they were first seen, but the latest research now confirms that they may actually be the remains of the ancient impacts that caused them: dark deposits left by the myriad of carbon-rich objects that struck Vesta over the past four-and-a-half billion years.

Even though Vesta had a completely molten surface 4.5 billion years ago it’s believed that its crust likely solidified within a few million years, making the 530-km (329-mile) -wide world a literal time capsule for events taking place in the inner Solar System since then… one reason why Vesta was chosen as a target for the Dawn mission.

Using data acquired by Dawn during its year in orbit around Vesta, a team led by researchers from Germany’s Max Planck Institute for Solar System Research and the University of North Dakota investigated the dark material seen lining the edges of large impact basins located on the protoplanet’s southern hemisphere. What they determined was that much of the material was delivered during an initial large, low-velocity impact event 2–3 billion years ago that created the largest basin — Veneneia — and was then partially covered by a later impact that created the smaller basin that’s nearly centered on Vesta’s southern pole — Rheasilva.

“The evidence suggests that the dark material on Vesta is rich in carbonaceous material and was brought there by collisions with smaller asteroids.”

– Vishnu Reddy, lead author, Max Planck Institute for Solar System Research and the University of North Dakota

Dawn framing camera images of dark material on Vesta. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Subsequent smaller asteroid impacts over the millennia likely brought more carbonaceous material to Vesta’s surface, both delivering it as well as revealing any that may have existed beneath brighter surfaces.

The dark, carbon-rich material observed on Vesta by Dawn also seems to match up with similarly dark clasts found in meteorites that have landed on Earth which are thought to have originated from Vesta.

“Our analysis of the dark material on Vesta and comparisons with laboratory studies of HED meteorites for the first time proves directly that these meteorites are fragments from Vesta,” said Lucille Le Corre from the Max Planck Institute for Solar System Research, another lead author of the study.

If evidence of such collisions between worlds can be found on Vesta, it’s likely that similar events were occurring all across the inner solar system during its early days, providing a clue as to how carbon-rich organic material was delivered to Earth — and possibly Mars as well. Such material — the dark stains we see today lining Vesta’s craters — would have helped form the very building blocks of life on our planet.

The team’s findings were published in the November/December issue of the journal Icarus.

Read more on the Max Planck Institute’s news page here, and on the NASA release here. Learn more about the Dawn mission in the video below, narrated by Leonard Nimoy.

December 28, 2012December 23, 2015 by Jason Major

How Long is a Day on Mercury?

1/3 the distance from the Sun than Earth, it should be no surprise that a day on Mercury is a real scorcher with temperatures soaring over 400 ºC. But in addition to its solar proximity it also has an extremely slow rotation: a single day on Mercury is 58.6 Earth days long… and you thought your Mondays lasted forever!

To be even more precise, for every 2 Mercury years, 3 Mercury days pass — a 3:2 spin-orbit resonance, caused by the planet’s varying elliptical orbit. (This also makes for some interesting motions of the Sun in Mercury’s sky.)

To illustrate this, UK’s The Open University has published a new video in their 60 Second Adventures in Astronomy series… check it out above (and see more of their excellent and amusing animations here.)

Video: The Open University. Narrated by David Mitchell.

December 24, 2012December 23, 2015 by Jason Major

A Color View of Darling Dione

Color-composite of Dione made from raw Cassini images acquired on Dec. 23, 2012. (NASA/JPL/SSI. Composite by J. Major.)

Although made mostly of ice and rock, Saturn’s moon Dione (pronounced dee-oh-nee) does have some color to it, as seen in this color-composite made from raw images acquired by Cassini on December 23.

700 miles (1120 km) wide, Dione is covered pole-to-pole in craters and crisscrossed by long, bright regions of “wispy line” terrain — the reflective faces of sheer ice cliffs and scarps that are too steep for darker material drifting in from Saturn’s E ring to remain upon.

The composite was assembled from raw images captured in red, green and blue visible light wavelengths by Cassini from a distance of 154,869 miles (249,238 km).

The view above looks at a region on Dione’s mid-northern hemisphere. The bright-walled crater in the center surrounded by warmer-hued terrain is named Creusa, and the long rift system next to it is Tibur Chasmata, which runs north-to-south. Dione’s north pole is to the upper left.

Dione’s heavily cratered areas are most common on its trailing hemisphere. Logically, a moon’s leading hemisphere should be the more heavily cratered, so it has been hypothesized that a relatively recent impact spun Dione around 180 degrees. The moon’s small size mean that even a modest-scale impact could have done the job.

Relative sizes of Earth, Moon and Dione (J. Major)

Dione orbits Saturn at a distance of 209,651 miles (377,400 km), closer than our Moon is to us.

See more images and news from the Cassini mission here. And for more on Dione, see some of my previous posts on Lights in the Dark.

October 22, 2012December 23, 2015 by Jason Major

Valles Marineris: The Grandest Canyon of All

A digital terrain model of a portion of Mars’ Valles Marineris, the largest canyon in the Solar System. Credit: ESA/DLR/FU Berlin (G. Neukum)

Anyone who’s visited the Grand Canyon in Arizona can attest to its beauty, magnificence and sheer sense of awe that comes upon approaching its rim, whether for the first time or hundred-and-first. “Grand” almost seems too inferior a title for such an enormous geological feature — yet there’s a canyon much, much bigger stretching across the surface of Mars, one that could easily swallow all of our Grand Canyon within one of its side gullies.

The image above, released online for the first time today by ESA, is a digital terrain model of a portion of Mars’ Valles Marineris: our Solar System’s grandest canyon.
It’s easy to fall into hyperbole when describing Valles Marineris. Named for NASA’s Mariner 9 spacecraft, which became the first spacecraft to orbit Mars on November 14, 1971, the canyon is over 4000 km long, 200 km wide, and 10 km deep (2,480 x 125 x 6 miles) — that’s five times deeper than the Grand Canyon and long enough to stretch across the entire contiguous United States! It’s a rift unparalleled on any other world in the Solar System.

Valles Marineris is thought to be the result of the formation of the nearby Tharsis volcanic region, home to Olympus Mons, the Solar System’s largest volcano. As the region swelled with magma billions of years ago the planet’s crust stretched and split, collapsing into a vast, deep canyon.

Much later, landslides and flowing water would help erode the canyon’s steep walls and carve out meandering side channels.

The 45-degree view above was was made from data acquired during 20 individual orbits of ESA’s Mars Express. It is presented in near-true color with four times vertical exaggeration (to increase relief contrast.) Download a high-res JPEG version here.

The largest portion of the canyon seen crossing left to right is known as Melas Chasma. Candor Chasma is the connecting trough to the north, and Hebes Chasma is in the far top left.

Below is a video released by JPL in 2006 showing a virtual fly-through of Valles Marineris, shown as if you were on a Grand Canyon-style helicopter sightseeing tour (that is, if helicopters could even work in the thin Martian air!)

Hopefully someday we’ll be seeing actual videos taken above Valles Marineris and photos captured from its rim… perhaps even by human explorers! (Please exit through the gift shop.)

Image source: ESA. Video by Eric M. De Jong and Phil Christiansen et. al, Arizona State University.