Archive
Sunset Jets On Rosetta’s Comet
ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
When night falls on Rosetta’s comet 67P/Churyumov-Gerasimenko, the bizarrely shaped body remains active. This can be seen in new images of the Ma’at region located on the comet’s “head” captured by OSIRIS, the scientific imaging system on board the Rosetta spacecraft. They were taken approximately half an hour after the Sun had set over the region and show clearly distinguishable jets of dust escaping into space. Researchers from the OSIRIS team believe that the increasing heating-up of the comet is responsible for the newly observed phenomenon.
“Only recently have we begun to observe dust jets persisting even after sunset”, says OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research (MPS) in Germany. In the past months, the comet’s activity originated from illuminated areas on the day side. As soon as the Sun set, these jets subsided and did not re-awake until after the next sunrise. An exception poses an image from 12 March, 2015 showing the onset of a dust jet on the brink of dawn.
The Moon Photobombs Uranus Live
Observers in eastern Australia, all of New Zealand, and parts of the South Pacific will see the planet Uranus pass behind the waning crescent Moon in the early morning of June 12, 2015. The precise timing of the event depends on your location. In Adelaide, Australia, Uranus passes behind the Moon at 18:49 UT, just after moonrise, and emerges from the dark part of the crescent Moon’s face at 19:57 UT. In Sydney the occultation begins at 19:01 UT and ends at 20:17 UT.
Observers in the rest of the world will see Uranus close to the crescent Moon in the eastern pre-dawn sky. This presents an excellent opportunity to spot this distant ice giant with a pair of binoculars or a small telescope. Slooh will be presenting live views of the event courtesy of our Australian feed partners. Join us to watch live views of the Solar System in motion!
Dawn Spirals Closer To Ceres, Returns A New View
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
A new view of Ceres, taken by NASA’s Dawn spacecraft on May 23, shows finer detail is 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. The image is part of a sequence taken for navigational purposes.
After transmitting these images to Earth on May 23, Dawn resumed ion-thrusting toward its second mapping orbit. On June 3, Dawn will enter this orbit and spend the rest of the month observing Ceres from 2,700 miles (4,400 kilometers) above the surface. Each orbit during this time will be about three days, allowing the spacecraft to conduct an intensive study of Ceres.
Hubble Finds Two Chaotically Tumbling Pluto Moons
Artist’s illustrations. Credit: NASA, ESA, M. Showalter (SETI Institute), and G. Bacon (STScI)
If you lived on one of Pluto’s moons Nix or Hydra, you’d have a hard time setting your alarm clock. That’s because you could not know for sure when, or even in which direction, the sun would rise.
A comprehensive analysis of all available Hubble Space Telescope data shows that two of Pluto’s moons, Nix and Hydra, are wobbling unpredictably. Scientists believe the other two small moons, Kerberos and Styx, are likely in a similar situation, pending further study.
“Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington, D.C. “When the New Horizons spacecraft flies through the Pluto system in July we’ll get a chance to see what these moons look like up close and personal.”
Why the chaos? Because the moons are embedded inside a dynamically shifting gravitational field caused by the system’s two central bodies, Pluto and Charon, whirling about each other. The variable gravitational field induces torques that send the smaller moons tumbling in unpredictable ways. This torque is strengthened by the fact the moons are football shaped rather than spherical.
Cassini Sends Final Close Views Of Odd Moon Hyperion
Image credit: NASA/JPL-Caltech/Space Science Institute
NASA’s Cassini spacecraft has returned images from its final close approach to Saturn’s oddball moon Hyperion, upholding the moon’s reputation as one of the most bizarre objects in the solar system. The views show Hyperion’s deeply impact-scarred surface, with many craters displaying dark material on their floors.
During this flyby, Cassini passed Hyperion at a distance of about 21,000 miles (34,000 kilometers) at closest approach. Cassini’s closest-ever Hyperion flyby took place on Sept. 26, 2005, at a distance of 314 miles (505 kilometers).
Hyperion is the largest of Saturn’s irregular, or potato-shaped, moons and may be the remnant of a violent collision that shattered a larger object into pieces. Cassini scientists attribute Hyperion’s peculiar, sponge-like appearance to the fact that it has an unusually low density for such a large object — about half that of water. Its low density indicates Hyperion is quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.
Link To Full Story And Other Links
NASA Instrument On Rosetta Makes Comet Atmosphere Discovery
Image credit: ESA/Rosetta/NAVCAM
Data collected by NASA’s Alice instrument aboard the European Space Agency’s Rosetta spacecraft reveal that electrons close to the surface of comet 67P/Churyumov-Gerasimenko — not photons from the sun, as had been believed — cause the rapid breakup of water and carbon dioxide molecules spewing from the comet’s surface.
“The discovery we’re reporting is quite unexpected,” said Alan Stern, principal investigator for the Alice instrument at the Southwest Research Institute (SwRI) in Boulder, Colorado. “It shows us the value of going to comets to observe them up close, since this discovery simply could not have been made from Earth or Earth orbit with any existing or planned observatory. And, it is fundamentally transforming our knowledge of comets.
A report of the findings has been accepted for publication by the journal Astronomy and Astrophysics.
NASA’s Europa Mission Begins With Selection Of Science Instruments
Bizarre features on Europa’s icy surface. Credits: NASA/JPL-Caltech
NASA has selected nine science instruments for a mission to Jupiter’s moon Europa, to investigate whether the mysterious icy moon could harbor conditions suitable for life.
NASA’s Galileo mission yielded strong evidence that Europa, about the size of Earth’s moon, has an ocean beneath a frozen crust of unknown thickness. If proven to exist, this global ocean could have more than twice as much water as Earth. With abundant salt water, a rocky sea floor, and the energy and chemistry provided by tidal heating, Europa could be the best place in the solar system to look for present day life beyond our home planet.
“Europa has tantalized us with its enigmatic icy surface and evidence of a vast ocean, following the amazing data from 11 flybys of the Galileo spacecraft over a decade ago and recent Hubble observations suggesting plumes of water shooting out from the moon,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “We’re excited about the potential of this new mission and these instruments to unravel the mysteries of Europa in our quest to find evidence of life beyond Earth.”
NASA Research Reveals Europa’s Mystery Dark Material Could Be Sea Salt
Image Credit: NASA/JPL-Caltech/SETI Institute
NASA laboratory experiments suggest the dark material coating some geological features of Jupiter’s moon Europa is likely sea salt from a subsurface ocean, discolored by exposure to radiation. The presence of sea salt on Europa’s surface suggests the ocean is interacting with its rocky seafloor — an important consideration in determining whether the icy moon could support life.
The study is accepted for publication in the journal Geophysical Research Letters and is available online.
“We have many questions about Europa, the most important and most difficult to answer being is there life? Research like this is important because it focuses on questions we can definitively answer, like whether or not Europa is inhabitable,” said Curt Niebur, Outer Planets Program scientist at NASA Headquarters in Washington. “Once we have those answers, we can tackle the bigger question about life in the ocean beneath Europa’s ice shell.”
Ceres Animation Showcases Bright Spots
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
The mysterious bright spots on the dwarf planet Ceres are better resolved in a new sequence of images taken by NASA’s Dawn spacecraft on May 3 and 4, 2015. The images were taken from a distance of 8,400 miles (13,600 kilometers). The animation is available at:
http://www.jpl.nasa.gov/spaceimages/details.php?id=pia19547
In this closest-yet view, the brightest spots within a crater in the northern hemisphere are revealed to be composed of many smaller spots. However, their exact nature remains unknown.
“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.
NJIT’s New Solar Telescope Unveils The Complex Dynamics Of Sunspots’ Dark Cores
NJIT’s Big Bear Solar Observatory
Groundbreaking images of the Sun captured by scientists at NJIT’s Big Bear Solar Observatory (BBSO) give a first-ever detailed view of the interior structure of umbrae – the dark patches in the center of sunspots – revealing dynamic magnetic fields responsible for the plumes of plasma that emerge as bright dots interrupting their darkness. Their research is being presented this week at the first Triennial Earth-Sun Summit meeting between the American Astronomical Society’s Solar Physics Division and the American Geophysical Union’s Space Physics and Aeronomy section in Indianapolis, Ind.
The high-resolution images, taken through the observatory’s New Solar Telescope (NST), show the atmosphere above the umbrae to be finely structured, consisting of hot plasma intermixed with cool plasma jets as wide as 100 kilometers.
“We would describe these plasma flows as oscillating cool jets piercing the hot atmosphere. Until now, we didn’t know they existed. While we have known for a long time that sunspots oscillate – moderate resolution telescopes show us dark shadows, or penumbral waves, moving across the umbra toward the edge of a sunspot – we can now begin to understand the underlying dynamics,” said Vasyl Yurchyshyn, a research professor of physics at NJIT and the lead author of two recent journal articles based on the NST observations.
AstroNews 