Is That a Big Crater on Pluto? Pyramidal Mountain Found on Ceres

You’re probably as eager as I am for new images of Pluto and Ceres as both New Horizons and Dawn push ever closer to their respective little worlds. Recent photos, of which there are only a few, reveal some wild new features including what appears to a large crater on Pluto.

The latest photo of Pluto (lower left) and its largest moon Charon taken on June 29. A large possible crater-like feature is visible at lower right. Charon shows intriguing dark markings. Pluto's diameter is  1,471 miles (700 miles smaller than Earth's Moon); Charon is 750 miles across. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
The latest photo of Pluto (lower left) and its largest moon Charon taken on June 29. A large possible crater-like feature is visible at lower right. Charon shows intriguing dark markings. Pluto’s diameter is 1,471 miles (700 miles smaller than Earth’s Moon); Charon is 750 miles across. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

In the end, this apparent large impact might only be a contrast effect or worse, an artifact of over-processing, but there’s no denying its strong resemblance to foreshortened, shadow-filled craters seen on the Moon and other moons. It’s also encouraging that an earlier photo from June 27 shows the same feature. But the “crater” is just so … big! Its size seems disproportionate to the Pluto’s globe and recalls Saturn’s 246-mile-wide moon Mimas with its 81-mile-wide crater Herschel.

Pluto (right) and Charon, with its unusual dark north polar cap or “anti-cap” in a photo taken by New Horizons’ long-range camera on June 19, 2015. Pluto’s 1,471 miles in diameter; Charon’s half that size. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Pluto (right) and Charon, showing an unusual dark north polar cap or “anti-cap” in a photo taken by New Horizons’ long-range camera on June 19, 2015. The two were about 20 million miles away at the time. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Astronomers speculate the impact that gouged out Herschel came perilously close to shattering the moon to pieces. If it does turn out to be an crater, Pluto’s surface opposite the impact will likely show many fractures. Not to be outdone, the dwarf planet’s largest moon, Charon, is starting to show a personality of its own with a prominent dark north polar cap.

Since polar caps are normally bright, icy features, some have referred to this one as an “anti-polar cap”. Speaking of ice, the bright rim around Pluto in the photo above may be nitrogen frost condensing out of Pluto’s scant atmosphere as it slowly recedes from the Sun. Think how cold it must have to get for nitrogen to freeze out. How about -346° F (-210° C)! For new images of the Pluto system, be sure to check the New Horizons LORRI gallery page.

Dawn took this photo of an intriguing pyramidal mountain on Ceres on June  14 from an altitude of 2,700 miles. It rises 3 miles above a relatively smooth surface. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Dawn took this photo of an intriguing pyramidal mountain (top center) on Ceres on June 14 from an altitude of 2,700 miles. It rises 3 miles above a relatively smooth surface. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Closer to home, new photos of Ceres show a peculiar, pyramid-shaped mountain towering 3 miles (5 km) high from a relatively smooth region between two large craters. Mountains poking from crater floors aren’t unusual. They’re tossed up after the crust later rebounds after a large impact. What makes this one unusual is the lack of an associated crater. Moreover, the mountain’s pale hue could indicate it’s younger than the surrounding landscape. As far as we can tell, it’s the only tall mountain on the face of the dwarf planet.

Another more overhead view of the mountain (right of center) taken by NASA's Dawn probe on June 6. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Another more overhead view of the mountain (right of center) taken by NASA’s Dawn probe on June 6. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Cropped version of the photo above. Notice the striations on the mountainside possibly from landslides. Credit:
Cropped version of the photo above. Notice the striations on the mountainside possibly from landslides. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The Dawn team also photographed that cluster of white spots again, this time with a very shot exposure in to eke out more details. What do you think? If you’re as interested in asteroids as I am, Italian astrophysicist Gianluca Masi, a frequent photo contributor to Universe Today, will host a special live Asteroid Day event today starting at 6 p.m. CDT (23:00 UT). Masi will review near-Earth asteroids, explain discovery techniques and observe several in real time.

The Dawn team greatly underexposed Ceres in order to tease out more details from the white spot cluster in this image made on June 15 from 2,700 miles altitude. I've lightened the limb of Ceres, so you can see the context better. Credit:
The Dawn team greatly underexposed Ceres in order to tease out more details from the white spot cluster in this image made on June 15 from 2,700 miles altitude. I’ve lightened the limb of Ceres to provide context. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Dawn photographed the large crater at left along with an interesting chain of craters and possible fault or collapse features. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Dawn photographed the large crater at left along with an interesting chain of craters and possible fault or collapse structures. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Ceres Has Lots of Bright Spots

Those bright mystery spots aren’t the only ones on Ceres. Recent photos posted on JPL’s Photojournal site  feature a spectacular rayed crater resembling the familiar lunar craters Kepler and Copernicus.

Unique view of the lunar crater Proclus showing an extension system of bright rays taken from Apollo 15. Credit: NASA
Unique view of the lunar crater Proclus showing an extension system of bright rays taken from Apollo 15. Credit: NASA
Bright dribs and drabs of material are seen in this photo taken by Dawn on May 22, 2015 from 3,200 miles (5,100 km). Credit: NASA
Bright dots and patches of material are seen in this photo taken by Dawn on May 22, 2015 from 3,200 miles (5,100 km) away. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Taken back on May 4 from 8,400 miles, this photo shows the rayed crater (bottom) and another bright spot. Credit:
Taken back on May 4 from 8,400 miles (13,600 km), this photo shows the rayed crater (bottom) and another bright spot above center. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Lunar rays are bright because they contrast with their older surroundings which have been darkened by exposure to solar and cosmic radiation. Impacts expose fresh material from below the surface that settles into a spider web of rays around the newly excavated crater. Huge boulders lofted above the Moon’s surface during the impact slam back into the crust to create secondary craters also crowned with bright dust and rock.

Based on Ceres' density, it contains a large fraction of low density materials including clays, water ice, salts and organic compounds. This schematic gives a general idea of the dwarf planet's makeup. Credit: NASA/ESA/STScI
Based on Ceres’ density, it contains a large fraction of low density materials including clays, water ice, salts and organic compounds. This schematic gives a general idea of the dwarf planet’s makeup. Credit: NASA/ESA/STScI

Most models of Ceres depict a rocky crust,  mantle of ice and a rocky inner core.  This makes us wonder if the bright material unearthed might be ice. If so, it would gradually vaporize on the virtually air-free dwarf planet.

Dawn will spend through early 2016 at Ceres during its primary mission and then remain in orbit there perpetually. We should be able to cipher the composition of the white material during that time with the spacecraft’s Gamma Ray and Neutron Detector and Visible and Infrared Mapping Spectrometer, but a lengthy stay might allow us to see changes in the extent of any ice exposures as they gradually vaporize away.

Uncropped, untoned view of the rayed crater seen in the earlier image. Credit:
Uncropped, untoned view of the rayed crater seen in the earlier image. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

One thing we know for certain about Ceres are its dimensions. Dawn observations have revised the size to be about 599 miles (963 km) across at the equator with a polar diameter of 554 miles (891 km). Like Earth and other planets, Ceres is a slightly flattened sphere wider at the equator than from pole to pole. The temperature there ranges from about -100°F (-73°C) during the day and dips to -225°F (-143°C) at night. That makes its daytime high about 28° warmer than coldest temperature ever recorded on Earth.

Ceres Bright Spots Keep Their Secret Even From 2,700 miles Up

Don’t get me wrong. I love this new photo. Dawn snapped it from its second mapping orbit from 2,700 miles up on June 6. The number of craters and the detail visible in the parallel troughs snaking through the scene are breathtaking. That’s why I hate to niggle about the white spots.

While they appear larger and sharper than images taken in May from a greater distance, they’re too bright to show much new detail. I can’t help but wonder if mission scientists might adjust the exposure a bit the next time around.

Tighter crop on the 55-mile crater that's home to the cluster of white spots. Credit:
Tighter crop on the 55-mile (90-km) crater that’s home to the cluster of white spots. I applied a small amount of sharpening and toned down the spots just a little. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

When photographing bright objects here on Earth, we expose “for the highlights” or the bright areas in photos to avoid overexposure and loss of detail.

What a satisfying view! NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
What a satisfying view! This image, also taken on June 6, shows a large crater in Ceres’ southern hemisphere as well as cracks and radial fractures possibly associated with impacts. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Naturally, when you try to capture details in something bright, your background will go dark. But that might be what’s needed here – a change in exposure to reveal more detail in the spots at the expense of the landscape. Doubtless NASA will release enlarged and detailed images of these enigmatic dots later this summer. Just call me impatient.

Scientists still don’t understand the nature of the spot cluster, but reflective ice or salt remain the strongest possibilities.

What is this - the Moon? A view of craters in Ceres' northern hemisphere from June 6, 2015. Credit: Bright Spots Shine in Newest Dawn Ceres Images VIR Image of Ceres, May 2015Bright Spots in Ceres' Second Mapping OrbitCeres' Southern Hemisphere in Survey Ceres' Northern Hemisphere in Survey Craters in the northern hemisphere of dwarf planet Ceres are seen in this image taken by NASA's Dawn spacecraft on June 6, 2015. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
A lunar-like landscape in Ceres’ northern hemisphere photographed on June 6, 2015. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“The bright spots in this configuration make Ceres unique from anything we’ve seen before in the solar system,” said Chris Russell, principal investigator for the Dawn mission. “The science team is working to understand their source. Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt.”

Images from Dawn's visible and infrared mapping spectrometer (VIR) show a portion of Ceres' cratered northern hemisphere, taken on May 16, 2015. From top to bottom, the views include a black-and-white image, a true-color view and a temperature image. The true-color view contains reddish dots that are image artifacts, which are not part of Ceres' surface.
Images from Dawn’s visible and infrared mapping spectrometer (VIR) show a portion of Ceres’ cratered northern hemisphere, taken on May 16, 2015 from 4,500 miles (7,300 km) away. From top to bottom, the views include a black-and-white image, a true-color view and a temperature image. In the bottom infrared view, the lightest areas are hottest and darkest are the coolest. Credit: NASA/JPL-Caltech/UCLA/ASI/INAF

It’s interesting to compare and contrast Ceres with Dawn’s first target asteroid, Vesta. Craters of every size dominate both small worlds, but Ceres shows evidence of a more activity in the form of relaxed crater rims (possibly due to ice deformation), landslides and collapsed structures.

Dawn takes about three days to orbit at its current 2,700 mile altitude. It will continue to take photos and make science observations until dropping into a new lower altitude of 900 miles (1, 450 km) in early August.

Dawn Does Dramatic Fly Over of Ceres, Enters Lower Mapping Orbit: Video

Video caption: This new video animation of Ceres was created from images taken by NASA’s Dawn spacecraft at altitudes of 8,400 miles (13,600 kilometers) and 3,200 miles (5,100 kilometers) away. Vertical dimension has been exaggerated by a factor of two and a star field added. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Scientists leading NASA’s Dawn mission to dwarf planet Ceres have just released a brand new animated video showing a dramatic fly over of the heavily cratered world featuring its mysterious bright spots whose exact origin and nature remain elusive.

Meanwhile, the venerable probe has just successfully entered its new and lower mapping orbit on June 3 from which researchers hope to glean hordes of new data to unravel the secrets of the bright spots and unlock the nature of Ceres origin and evolution.

Pockmarked Ceres is an alien world unlike any other in our solar system.

“Dawn completed the maneuvering to reach its second mapping orbit and stopped ion-thrusting on schedule. Since May 9, the spacecraft has reduced its orbital altitude from 8,400 miles (13,600 kilometers) to 2,700 miles (4,400 kilometers),” reported Marc Rayman, Dawn Chief Engineer/ Mission Director of NASA’s Jet Propulsion Laboratory, Pasadena, California.

“As Dawn flew 2,700 miles (4,400 kilometers) over Ceres’ north pole on June 5 that marked the beginning of the new mapping phase, and Dawn began taking photos and making other measurements on schedule.”

Each orbit of Dawn around Ceres at this second science mapping orbit lasts 3.1 days.

The new video was created by the research team based on observations of Ceres that were taken from Dawn’s initial mapping orbit, at an altitude of 8,400 miles (13,600 kilometers), as well as the most recent navigational images taken from 3,200 miles (5,100 kilometers), according to NASA.

It is based on data from over 80 images captured by Dawn’s framing cameras which were provided The German Aerospace Center (DLR) and Max Planck Institute for Solar System Research in Göttingen, Germany.

The images were used to provide a three-dimensional video view. The vertical dimension is exaggerated by a factor of two in the video.

“We used a three-dimensional terrain model that we had produced based on the images acquired so far,” said Dawn team member Ralf Jaumann of the German Aerospace Center (DLR), in Berlin.

“They will become increasingly detailed as the mission progresses — with each additional orbit bringing us closer to the surface.”

Imagery of the mysterious bright spots show them to seemingly be sheets of many spots of water ice, and not just single huge patches. The famous duo of ice spots are located inside the middle of a 57 miles (92 kilometers) wide crater situated in Ceres northern hemisphere.

Dawn is an international science mission managed by NASA’s Jet Propulsion Laboratory, Pasadena, California. The trio of science instruments are from the US, Germany and Italy.

The framing camera was provided by the Max Planck Institute for Solar System Research, Göttingen, Germany and the German Aerospace Center (DLR).

This view of Ceres was taken by Dawn spacecraft on May 23 and shows finer detail becoming visible on the dwarf planet. The spacecraft snapped the image at a distance of 3,200 miles (5,100 kilometers) with a resolution of 1,600 feet (480 meters) per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
This view of Ceres was taken by Dawn spacecraft on May 23 and shows finer detail becoming visible on the dwarf planet. The spacecraft snapped the image at a distance of 3,200 miles (5,100 kilometers) with a resolution of 1,600 feet (480 meters) per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn will spend most if June at this second mapping orbit before firing up the ion engines and spiraling yet lower for a mission expected to last until at least June 2016.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

Dawn’s spiral descent from its first mapping orbit (RC3) to its second (survey). The two mapping orbits are shown in green. The color of Dawn’s trajectory progresses through the spectrum from blue, when it began ion-thrusting on May 9, to red, when ion-thrusting concludes on June 3. The red dashed sections show where Dawn is coasting, mostly for telecommunications. The first two coast periods include OpNav 8 and 9. Image credit: NASA/JPL-Caltech
Dawn’s spiral descent from its first mapping orbit (RC3) to its second (survey). The two mapping orbits are shown in green. The color of Dawn’s trajectory progresses through the spectrum from blue, when it began ion-thrusting on May 9, to red, when ion-thrusting concludes on June 3. The red dashed sections show where Dawn is coasting, mostly for telecommunications. The first two coast periods include OpNav 8 and 9. Image credit: NASA/JPL-Caltech

Ceres’ White Spots Multiply in Latest Dawn Photos

We don’t know exactly what those mysterious white spots on Ceres are yet, but we’re getting closer to an explanation. Literally. The latest images from the Dawn spacecraft taken a mere 8,400 miles from the dwarf planet Ceres reveal that the pair of  spots are comprised of even more spots. 

“Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice,” said Christopher Russell, principal investigator for the Dawn mission from the University of California, Los Angeles.

This animation shows a sequence of images taken by NASA's Dawn spacecraft on May 4, 2015, from a distance of 8,400 miles (13,600 kilometers), in its RC3 mapping orbit. The image resolution is 0.8 mile (1.3 kilometers) per pixel. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
This animation shows a sequence of images taken by NASA’s Dawn spacecraft on May 4, 2015, from a distance of 8,400 miles (13,600 km), in its RC3 or science mapping orbit. The image resolution is 0.8 mile (1.3 km) per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn recently concluded its first science orbit, making a 15-day full circle around Ceres while gathering data with its suite of science instruments. This past Saturday, May 9, its ion engine fired once again to lower the spacecraft to its second science orbit which it will enter on June 6. On that date, the probe will hover just 2,700 miles (4,400 km) above the dwarf planet and begin a comprehensive mapping of the surface. Scientists also hope the bird’s eye view will reveal clues of ongoing geological activity.


Check out this great video compiled from Dawn’s still frames of Ceres by Tom Ruen. Almost feels like you’re there.

There’s no doubt a lot’s been happening on Ceres. One look at all those cracks hint at either impact-related stresses some kind of crustal expansion. Geological processes may still make this little world rock and roll.

In this uncropped single frame, not only are multiple white spots visible but also long, parallel cracks or troughs in Ceres' surface. Credit:
In this uncropped single frame, not only are multiple white spots visible but also long, roughly parallel cracks or troughs in Ceres’ surface. Are they impact-related or caused by some other stress? Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Fortunately, we won’t have to wait till next month for more photos. NASA plans to pause the probe twice on the way down to shoot and send fresh images.

Dawn Rises Over Ceres North Pole

Brand new images taken on April 10 by NASA’s Dawn probe show the dwarf planet from high above its north pole. Photographed at a distance of just 21,000 miles (33,000 km) — less than 1/10 the Earth-moon distance — they’re our sharpest views to date. The crispness combined with the low-angled sunlight gives Ceres a stark, lunar-like appearance.

Artist's concept of Dawn above Ceres around the time it was captured into orbit by the dwarf planet in early March. Since its arrival, the spacecraft turned around to point the blue glow of its ion engine in the opposite direction. Image credit: NASA/JPL
Artist’s concept of Dawn above Ceres around the time it was captured into orbit by the dwarf planet in early March. Since its arrival, the spacecraft turned around to point the blue glow of its ion engine in the opposite direction. Because it’s been facing the Sun while lowering its orbit, the new images of Ceres show it as a crescent. Credit: NASA/JPL

Images will only get better. Dawn arrived at Ceres on March 6 and immediately got to work using its ion thrusters in conjunction with the dwarf planet’s gravity to gradually lower itself into a circular orbit. Once the spacecraft settles into its first science orbit on April 23 at a distance of 8,400 miles from the surface, it will begin taking a hard look at this cratered mini-planet.  A little more than two weeks later, the probe will spiral down for an even closer view on May 9.

The map is an enhanced color view that offers an expanded range of the colors visible to human eyes. Pictures were taken using blue, green and infrared filters and combined. Scientists use this technique to highlight subtle color differences across Ceres, which can provide insights into the physical properties and composition of the surface.  Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/ID
The map is an enhanced color view that offers an expanded range of the colors visible to human eyes. Pictures were taken using blue, green and infrared filters and combined. Scientists use this technique to highlight subtle color differences across Ceres, which can provide insights into the physical properties and composition of the surface. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/ID

Dawn’s gravity spiral continues throughout the summer and fall until the probe tiptoes down to just 233 miles (375 km) altitude in late November. From there it will deploy its Gamma Ray and Neutron Detector (GRaND) to map the elements composing Ceres’ surface rocks. We’re in for a great ride!


Simulated Ceres rotation by Tom Ruen using the new color map

Meanwhile, scientists have assembled images taken by Dawn through blue, green and infrared filters to create a new color-enhanced map of the dwarf planet. The variety of landforms in conjunction with the color variations hint that Ceres was once an active body or one with the means to resurface itself from within. Mechanisms might involve internal heating and / or movement of water or ice.

Pictures from Dawn’s VIR instrument highlight two regions on Ceres containing bright spots. The top images show a region scientists labeled “1” and the bottom images show the region labeled “5,” which show the Ceres’ brightest pair of spots. Region 1 is cooler than the rest of Ceres’ surface, but region 5 appears to be located in a region that is similar in temperature to its surroundings. Credit: NASA/JPL-Caltech/UCLA/ASI/INAF
Pictures from Dawn’s VIR instrument highlight two regions on Ceres containing bright spots. The top images show a region scientists labeled “1” and the bottom images show the region labeled “5,” which show the Ceres’ brightest pair of spots. Region 1 is cooler than the rest of Ceres’ surface, but region 5 appears to be located in a region that is similar in temperature to its surroundings. Credit: NASA/JPL-Caltech/UCLA/ASI/INAF

There are still no new close-ups of the pair of enigmatic white spots taunting us from inside that 57-mile-wide crater. But there is a bit of news. Dawn’s visible and infrared mapping spectrometer or VIR has already examined Ceres in visible and infrared or thermal light. Data from VIR indicate that light and darker regions on the dwarf planet have different properties.

A topographic map of Ceres with provisional names given to each quadrangle. Ceres' craters are named for agricultural gods; other features after world agricultural festivals. Credit: NASA / JPL / UCLA / MPS / DLR / IDA / JohnVV / Emily Lakdawalla
A topographic map of Ceres with provisional names given to each quadrangle. Ceres’ craters are named for agricultural gods; other features after world agricultural festivals. Let’s hope the names are made permanent. I mean, you can’t beat Yumyum. Credit: NASA / JPL / UCLA / MPS / DLR / IDA / JohnVV / Emily Lakdawalla

The bright spots are located in a region with a temperature similar to its surroundings. However, a different bright feature appears in a region that’s cooler than the neighboring surface. Exactly what those variations are telling us will hopefully become clear once Dawn returns more detailed images:

“The bright spots continue to fascinate the science team, but we will have to wait until we get closer and are able to resolve them before we can determine their source,” said Chris Russell, principal investigator for the Dawn mission.

Seeking Ceres: Following the Brave New World Through 2015

A little world is making big headlines in 2015. NASA’s Dawn spacecraft entered orbit around 1 Ceres on March 6th, 2015, gaving us the first stunning images of the ~900 kilometre diameter world. But whether you refer to Ceres as a dwarf planet, minor planet, or the king of the asteroid belt, this corner of the solar system’s terra incognita is finally open for exploration. It has been a long time coming, as Ceres has appeared as little more than a wandering, star-like dot in the telescopes of astronomers for over two centuries since discovery.

Untitled
The orbit of 1 Ceres. Credit: NASA/JPL

And the good news is, you can observe Ceres from your backyard if you know exactly where to look for it with binoculars or a small telescope. We’ll admit, we had an ulterior motive on pulling the trigger on this post three months prior to opposition on July 24th, as Dawn will soon be exiting its ‘shadow phase’ and start unveiling the world to us up close. The first science observations for Dawn begin in mid-April.

Credit
The path of Ceres through the remainder of 2015. Credit: Starry Night Software.

Ceres spends all of 2015 looping through the constellations of Capricornus, Microscopium and Sagittarius. This places it low to the south for northern hemisphere observers on April 1st in the early morning sky. Ceres will pass into the evening sky by mid-summer. Ceres orbits the Sun once every 4.6 years in a 10.6 degree inclination path relative to the ecliptic that takes it 2.6 AU to 3 AU from the Sun. The synodic period of Ceres is, on average, 467 days from one opposition to the next.

Ceres
Ceres, Vesta and Mars group together in 2014. Image credit and copyright: Mary Spicer

Shining at magnitude +8, April 1st finds Ceres near the Capricornus/Sagittarius border. Ceres can reach magnitude +6.7 during a favorable opposition. Note that Ceres is currently only 20 degrees east of the position of Nova Sagittarii 2015 No. 2, currently still shining at 4th magnitude. June 29th and November 25th are also great times to hunt for Ceres in 2015 as it loops less than one degree past the 4th magnitude star Omega Capricorni.

June 30
Ceres meets up with Omega Capricorni on June 29th. Credit: Stellarium.

You can nab Ceres by carefully noting its position against the starry background from night to night, either by sketching the suspect field, or photographing the region. Fans of dwarf planets will recall that 1 Ceres and 4 Vesta fit in the same telescopic field of view last summer, and now sit 30 degrees apart. Ceres is now far below the ecliptic plane, but will resume getting occulted by the passing Moon on February 3rd, 2017.

Left
The Palermo transit instrument used to discover Ceres. From Della Specola Astronomica (1792)

Ceres was discovered by Giuseppe Piazzi on the first day of the 19th century on January 1st, 1801. Ceres was located on the Aries/Cetus border just seven degrees from Mars during discovery. Piazzi wasn’t even on the hunt for new worlds at the time, but was instead making careful positional measurements of stars with the 7.5 centimetre Palermo Circle transit telescope.

Credit
A 1802 publication by Piazzi describing his discovery of Ceres. Credit: Image in the Public Domain.

At the time, the discovery of Ceres was thought to provide predictive proof of the Titus-Bode law: here was a new planet, just where this arcane numerical spacing of the planets said it should be. Ceres, however, was soon joined by the likes of Juno, Pallas, Vesta and many more new worldlets, as astronomers soon came to realize that the solar system was not the neat and tidy place that it was imagined to be in the pre-telescopic era.

To date, the Titus-Bode law remains a mathematical curiosity, which fails to hold up to the discovery of brave new exoplanetary systems that we see beyond our own.

Credit
Piazzi’s 1801 log describing the motion of Ceres against the starry background. Credit: Monatliche Correspondenz

The view from Ceres itself would be a fascinating one, as an observer on the Cererian surface would be treated to recurrent solar transits of interior solar system worlds. Mercury would be the most frequent, followed by Venus, which transits the Sun as seen from Ceres 3 times in the 21st century: August 1st, 2042, November 19th, 2058 and February 13th 2068. Mars actually transits the Sun as seen from Ceres even earlier on June 9th, 2033. Curiously, we found no transits of the Earth as seen from Ceres during the current millennium from 2000 to 3000 AD!

From Ceres, Jupiter would also appear 1.5’ in diameter near opposition, as opposed to paltry maximum of 50” in size as seen from the Earth. This would be just large enough for Jupiter to exhibit a tiny disk as seen from Ceres with the unaided eye. The four major Galilean moons would be visible as well.

Credit
The 2033 solar transit of Mars as seen from Ceres. Credit: Starry Night Education Software.

The mysteries of Ceres beckon. Does the world harbor cryovolcanism? Just what are those two high albedo white dots? Are there any undiscovered moons orbiting the tiny world? If a fair amount of surface ice is uncovered, Ceres may soon become a more attractive target for human exploration than Mars.

All great thoughts to ponder, as this stellar speck in the eyepiece of your backyard telescope becomes a brand new world full of exciting possibilities.

 

Scientists in Orbit Over Dawn’s Arrival at Ceres


Dawn’s approach and trajectory as it begins its orbital “dance” with Ceres. As you watch, note the timeline at upper right.

Dawn made it! After a 14-month tour of the asteroid Vesta and 2 1/2 years en route to Ceres, the spacecraft felt the gentle tug of Ceres gravity and slipped into orbit around the dwarf planet at 6:39 a.m. (CST) Friday morning.

“We feel exhilarated,” said lead researcher Chris Russell at the University of California, Los Angeles, after Dawn radioed back the good news. 

 

Not only is this humankind’s first probe to orbit a dwarf planet, Dawn is the only spacecraft to fly missions to two different planetary bodies. Dawn’s initial orbit places it 38,000 miles (61,000 km) from Ceres with a view of the opposite side of Ceres from the Sun. That’s why we’ll be seeing photos of the dwarf planet as a crescent for the time being. If you watch the video, you’ll notice that Dawn won’t see Ceres’ fully sunlit hemisphere until early-mid April.

Dawn’s spiral descent from survey orbit to the high altitude mapping orbit. The trajectory progresses from blue to red over the course of the six weeks. The red dashed segments are where the spacecraft is not thrusting with its ion propulsion system (as explained in April). Credit: NASA/JPL - See more at: http://dawnblog.jpl.nasa.gov/2014/06/30/dawn-journal-june-30-2/#sthash.CZ2WGsDQ.dpuf
Dawn’s spiral descent from survey orbit to the high altitude mapping orbit. The trajectory progresses from blue to red over the course of the six weeks. The red dashed segments are where the spacecraft is not thrusting with its ion propulsion system. Credit: NASA/JPL

The spacecraft will spend the next month gradually spiraling down to Ceres to reach its “survey orbit” of 2,730 miles in April. From there it will train its science camera and visible and infrared mapping spectrometer  to gather pictures and data. The leisurely pace of the orbit will allow Dawn to spend more than 37 hours examining Ceres’ dayside per revolution. NASA will continue to lower the spacecraft throughout the year until it reaches its minimum altitude of 235 miles.

As Dawn maneuvers into orbit, its trajectory takes it to the opposite side of Ceres from the sun, providing these crescent views. These additional pictures were taken on March 1 at a distance of 30,000 miles (49,000 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
As Dawn maneuvers into orbit, its trajectory takes it to the opposite side of Ceres from the sun, providing these crescent views. These additional pictures were taken on March 1 at a distance of 30,000 miles (49,000 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet,” said Marc Rayman, Dawn chief engineer and mission director at JPL. “Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres, home.”

More about Dawn’s incredible accomplishment can be found in the excellent Dawn Journal, written by Dawn chief engineer and mission director Marc Rayman.

What Your Breakfast has in Common with Ceres

On March 6, the Dawn spacecraft will ease into orbit around the dwarf planet Ceres. This is the visit to a dwarf planet (New Horizons will flyby Pluto later this year) and scientists are eager to see its surface in detail. But did you know that Ceres got its name from the ancient Roman goddess of agriculture and grain crops? Think about that when you enjoy your breakfast!

As we mentioned in our previous article about the intriguing white spots that Dawn has seen on Ceres as it makes its approach, Dawn will then continue to spiral its way down to an altitude of about 920 miles (1,480 kilometers), and in August 2015 will begin a two-month phase known as the high-altitude mapping orbit. Then, it will spiral down to an altitude of about 2,750 miles (4,430 kilometers), and obtain more science data in its survey science orbit. This phase will last for 22 days, and is designed to obtain a global view of Ceres with Dawn’s framing camera, and global maps with the visible and infrared mapping spectrometer (VIR).

Dawn will then continue to spiral its way down to an altitude of about 920 miles (1,480 kilometers), and in August 2015 will begin a two-month phase known as the high-altitude mapping orbit. During this phase, the spacecraft will continue to acquire near-global maps with the VIR and framing camera at higher resolution than in the survey phase. The spacecraft will also image in “stereo” to resolve the surface in 3-D.

Then, after spiraling down for two months, Dawn will begin its closest orbit around Ceres in late November, at a distance of about 233 miles (375 kilometers). The dance at low-altitude mapping orbit will be a long waltz — three months — and is specifically designed to acquire data with Dawn’s gamma ray and neutron detector (GRaND) and gravity investigation. GRaND will reveal the signatures of the elements on and near the surface. The gravity experiment will measure the tug of the dwarf planet, as monitored by changes in the high-precision radio link to NASA’s Deep Space Network on Earth.

Dawn’s nominal mission to Ceres is expected to last for 16 months.

Find out more about the mission at the Dawn website.

Bright Spots on Ceres Likely Ice, Not Cryovolcanoes

As the Dawn spacecraft prepares to enter orbit around Ceres on March 6, the science team provided the latest images and a mission preview during a briefing on March 2. The images released yesterday show more of those unusual bright spots and lots of craters, and feature two new global views of Ceres: one spinning globe, and a mosaic of a flat map-view of Ceres’ surface.

But the most-talked about feature is the 90-km-wide (57-mile) crater with two bright spots.

“These spots are extremely surprising and have been puzzling to the team and everyone that has seen them,” said Deputy Principal Investigator Carol Raymond. “The team is really, really excited about this feature because it is unique in the solar system.”

Raymond added that the team will be revealing the true nature of spots with the public in real time as the spacecraft gets closer and is able to make a determination.

So what is the leading theory on the bright spots?

The surface of Ceres is covered with craters of many shapes and sizes, as seen in this new mosaic of the dwarf planet comprised of images taken by NASA's Dawn mission on Feb. 19, 2015 from a distance of nearly 29,000 miles (46,000 kilometers). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
The surface of Ceres is covered with craters of many shapes and sizes, as seen in this new mosaic of the dwarf planet comprised of images taken by NASA’s Dawn mission on Feb. 19, 2015 from a distance of nearly 29,000 miles (46,000 kilometers). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

While cryovolcanoes have been bantered around as a possibility, during the briefing yesterday the science team downplayed that possibility, citing several pieces of evidence.

First, Raymond said the spots are consistent with highly reflective materials that may contain ice or salts. As an example of this, this morning, Cassini imaging lead Carolyn Porco tweeted an image of exposures of bright ice on Saturn’s moon Phoebe.

Raymond added that if the bright features end up to be liquid water, salt would be most likely element that would keep the water from freezing. The science team will also be looking for dust levitating from the surface, as sublimating gases could cause dust to rise.

Secondly, Raymond said if the bright spots were a cryovolcano, they would expect to see some type of surface evidence of a mound, peak or crack. “We don’t see that with the bright spots so a cryovolcano is unlikely,” she said.

NASA's Dawn spacecraft took these images of dwarf planet Ceres from about 25,000 miles (40,000 kilometers) away on Feb. 25, 2015. Ceres appears half in shadow because of the current position of the spacecraft relative to the dwarf planet and the sun. The resolution is about 2.3 miles (3.7 kilometers) per pixel.  Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
NASA’s Dawn spacecraft took these images of dwarf planet Ceres from about 25,000 miles (40,000 kilometers) away on Feb. 25, 2015. Ceres appears half in shadow because of the current position of the spacecraft relative to the dwarf planet and the sun. The resolution is about 2.3 miles (3.7 kilometers) per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

Third, — and this is also for anyone who may be thinking there is a beam or light-creating mechanism on the surface — team member Chris Russell said there is quite conclusive evidence that the spots are reflecting light, not creating light.

“We have followed the light curve into the terminator,” he said. “The spots do get darker and then go out when the terminator is reached.”

The terminator is the term for the boundary between day and night.

Lastly, even though in 2014 the Herschel spacecraft detected water vapor coming from two longitudal regions on Ceres (one of them is the region where crater with the bright spots is located), the current evidence points to the vaporization or sublimation of ice, not a spewing cryovolcano.

The Herschel team estimated that approximately 6 kg of water vapor is being produced per second, requiring only a tiny fraction of Ceres to be covered by water ice. This links nicely to the two localized surface features that the Herschel team observed and to the bright spots observed by Dawn.

Raymond said the Dawn science team should be able to verify the Herschel emissions, as they have modeled a similar emission coming from a distributed area and they are confident that observations with Dawn’s infrared spectrometer could detect such an emission, if present. “So if the activity is still ongoing, or if it is coming from a deposit left behind, we should be able to detect it,” she said.

This image was taken by NASA's Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Image Credit:  NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
This image was taken by NASA’s Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

After Dawn enters orbit, it will make its first full characterization of Ceres later in April, at an altitude of about 8,400 miles (13,500 kilometers), and it will then spiral down to an altitude of about 2,750 miles (4,430 kilometers), and obtain more science data in its survey science orbit. This phase will last for 22 days, and is designed to obtain a global view of Ceres with Dawn’s framing camera, and global maps with the visible and infrared mapping spectrometer (VIR).

Dawn will then continue to spiral its way down to an altitude of about 920 miles (1,480 kilometers), and in August 2015 will begin a two-month phase known as the high-altitude mapping orbit. During this phase, the spacecraft will continue to acquire near-global maps with the VIR and framing camera at higher resolution than in the survey phase. The spacecraft will also image in “stereo” to resolve the surface in 3-D.

Then, after spiraling down for two months, Dawn will begin its closest orbit around Ceres in late November, at a distance of about 233 miles (375 kilometers), allowing Dawn’s gamma ray and neutron detector (GRaND) and gravity investigation to make their observations.

Dawn’s nominal mission to Ceres is expected to last for 16 months, until near the end of 2016. There is a possibility of an extended mission, but that will depend on the amount of fuel left in the Dawn’s tank. While Dawn’s ion engine is nearly limitless in its power, hydrazine is used for attitude control or pointing the spacecraft – pointing it to Ceres to take images and pointing it back to Earth to send data. Robert Mase, Dawn project manager said the hydrazine the most scarce resource in terms of an extended mission.

“There’s not a likely prospect of years and years ahead of us,” he said.

Jim Green, director of NASA’s Planetary Science Division said while Dawn has plenty of fuel for its nominal mission, it likely won’t last more than a few months in an extended mission.

“We will take stock of how much hydrazine is left and then go through a process of evaluation if we can give the go ahead for an extended mission,” he said. “I’m sure it will observe some really exciting things, but we have to see what the fuel reserves are before we make that decision.”

Still, Dawn will remain in a stable orbit around Ceres for hundreds of years.

See all the latest imagery from Dawn at NASA’s Photojournal page.