Article written by Matt Williams
Published on Universe Today
February 21, 2017
In 2006, during their 26th General Assembly, the International Astronomical Union (IAU) adopted a formal definition of the term “planet”. This was done in the hopes of dispelling ambiguity over which bodies should be designated as “planets”, an issue that had plagued astronomers ever since they discovered objects beyond the orbit of Neptune that were comparable in size to Pluto.
Needless to say, the definition they adopted resulted in fair degree of controversy from the astronomical community. For this reason, a team of planetary scientists – which includes famed “Pluto defender” Alan Stern – have come together to propose a new meaning for the term “planet”. Based on their geophysical definition, the term would apply to over 100 bodies in the Solar System, including the Moon itself.
Read the complete article at the Universe Today website: SAD ABOUT PLUTO? HOW ABOUT 110 PLANETS IN THE SOLAR SYSTEM INSTEAD?
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By Matt Williams
Matt Williams is the Curator of the Guide to Space for Universe Today, a regular contributor to HeroX, a science fiction author, and a Taekwon-Do instructor. He lives with his family on Vancouver Island in beautiful BC.
This work is licensed under a Creative Commons Attribution 4.0 International License
Features on dwarf planet Ceres that piqued the interest of scientists throughout 2015 stand out in exquisite detail in the latest images from NASA’s Dawn spacecraft, which recently reached its lowest-ever altitude at Ceres.
Dawn took these images near its current altitude of 240 miles (385 kilometers) from Ceres, between Dec. 19 and 23, 2015.
Kupalo Crater, one of the youngest craters on Ceres, shows off many fascinating attributes at the high image resolution of 120 feet (35 meters) per pixel. The crater has bright material exposed on its rim, which could be salts, and its flat floor likely formed from impact melt and debris. Researchers will be looking closely at whether this material is related to the “bright spots” of Occator Crater. Kupalo, which measures 16 miles (26 kilometers) across and is located at southern mid-latitudes, is named for the Slavic god of vegetation and harvest.
“This crater and its recently-formed deposits will be a prime target of study for the team as Dawn continues to explore Ceres in its final mapping phase,” said Paul Schenk, a Dawn science team member at the Lunar and Planetary Institute, Houston.
Dawn’s low vantage point also captured the dense network of fractures on the floor of 78-mile-wide (126-kilometer-wide) Dantu Crater. One of the youngest large craters on Earth’s moon, called Tycho, has similar fractures. This cracking may have resulted from the cooling of impact melt, or when the crater floor was uplifted after the crater formed.
A 20-mile (32-kilometer) crater west of Dantu is covered in steep slopes, called scarps, and ridges. These features likely formed when the crater partly collapsed during the formation process. The curvilinear nature of the scarps resembles those on the floor of Rheasilvia, the giant impact crater on protoplanet Vesta, which Dawn orbited from 2011 to 2012.
Dawn’s other instruments also began studying Ceres intensively in mid-December. The
visible and infrared mapping spectrometer is examining how various wavelengths of light are reflected by Ceres, which will help identify minerals present on its surface.
Dawn’s gamma ray and neutron detector (GRaND) is also keeping scientists busy. Data from GRaND help researchers understand the abundances of elements in Ceres’ surface, along with details of the dwarf planet’s composition that hold important clues about how it evolved.
The spacecraft will remain at its current altitude for the rest of its mission, and indefinitely afterward. The end of the prime mission will be June 30, 2016.
“When we set sail for Ceres upon completing our Vesta exploration, we expected to be surprised by what we found on our next stop. Ceres did not disappoint,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles. “Everywhere we look in these new low- altitude observations, we see amazing landforms that speak to the unique character of this most amazing world.”
Dawn is the first mission to visit a dwarf planet, and the first mission outside the Earth-moon system to orbit two distinct solar system targets. After orbiting Vesta for 14 months in 2011 and 2012, it arrived at Ceres on March 6, 2015.
Dawn’s mission is managed by the Jet Propulsion Laboratory for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission
Flowing ice and a surprising extended haze are among the newest discoveries from NASA’s New Horizons mission, which reveal distant Pluto to be an icy world of wonders.“We knew that a mission to Pluto would bring some surprises, and now — 10 days after closest approach — we can say that our expectation has been more than surpassed,” said John Grunsfeld, NASA’s associate administrator for the Science Mission Directorate. “With flowing ices, exotic surface chemistry, mountain ranges, and vast haze, Pluto is showing a diversity of planetary geology that is truly thrilling.”
Just seven hours after closest approach, New Horizons aimed its Long Range Reconnaissance Imager (LORRI) back at Pluto, capturing sunlight streaming through the atmosphere and revealing hazes as high as 80 miles (130 kilometers) above Pluto’s surface. A preliminary analysis of the image shows two distinct layers of haze — one about 50 miles (80 kilometers) above the surface and the other at an altitude of about 30 miles (50 kilometers).
“My jaw was on the ground when I saw this first image of an alien atmosphere in the Kuiper Belt,” said Alan Stern, principal investigator for New Horizons at the Southwest Research Institute (SwRI) in Boulder, Colorado. “It reminds us that exploration brings us more than just incredible discoveries — it brings incredible beauty.”
Studying Pluto’s atmosphere provides clues as to what’s happening below.
“The hazes detected in this image are a key element in creating the complex hydrocarbon compounds that give Pluto’s surface its reddish hue,” said Michael Summers, New Horizons co-investigator at George Mason University in Fairfax, Virginia.
Models suggest the hazes form when ultraviolet sunlight breaks up methane gas particles — a simple hydrocarbon in Pluto’s atmosphere. The breakdown of methane triggers the buildup of more complex hydrocarbon gases, such as ethylene and acetylene, which also were discovered in Pluto’s atmosphere by New Horizons. As these hydrocarbons fall to the lower, colder parts of the atmosphere, they condense into ice particles that create the hazes. Ultraviolent sunlight chemically converts hazes into tholins, the dark hydrocarbons that color Pluto’s surface.
Scientists previously had calculated temperatures would be too warm for hazes to form at altitudes higher than 20 miles (30 kilometers) above Pluto’s surface.
“We’re going to need some new ideas to figure out what’s going on,” said Summers.
The New Horizons mission also found in LORRI images evidence of exotic ices flowing across Pluto’s surface and revealing signs of recent geologic activity, something scientists hoped to find but didn’t expect.
The new images show fascinating details within the Texas-sized plain, informally named Sputnik Planum, which lies within the western half of Pluto’s heart-shaped feature, known as Tombaugh Regio. There, a sheet of ice clearly appears to have flowed — and may still be flowing — in a manner similar to glaciers on Earth.
“We’ve only seen surfaces like this on active worlds like Earth and Mars,” said mission co-investigator John Spencer of SwRI. “I’m really smiling.”
Additionally, new compositional data from New Horizons’ Ralph instrument indicate the center of Sputnik Planum is rich in nitrogen, carbon monoxide, and methane ices.
“At Pluto’s temperatures of minus-390 degrees Fahrenheit, these ices can flow like a glacier,” said Bill McKinnon, deputy leader of the New Horizons Geology, Geophysics and Imaging team at Washington University in St. Louis. “In the southernmost region of the heart, adjacent to the dark equatorial region, it appears that ancient, heavily-cratered terrain has been invaded by much newer icy deposits.”
View a simulated flyover using New Horizons’ close-approach images of Sputnik Planum and Pluto’s newly-discovered mountain range, informally named Hillary Montes, in the video: http://go.nasa.gov/1MMEdTb
The New Horizons mission will continue to send data stored in its onboard recorders back to Earth through late 2016. The spacecraft currently is 7.6 million miles (12.2 million kilometers) beyond Pluto, healthy and flying deeper into the Kuiper Belt.
The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft, and manages the mission for NASA’s Science Mission Directorate. SwRI, based in San Antonio, leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.
For more information on the New Horizons mission, including fact sheets, schedules, video and images, visit: http://www.nasa.gov/newhorizons
A new color map of dwarf planet Ceres, which NASA’s Dawn spacecraft has been orbiting since March, reveals the diversity of the surface of this planetary body. Differences in morphology and color across the surface suggest Ceres was once an active body, Dawn researchers said today at the 2015 General Assembly of the European Geosciences Union in Vienna.
“This dwarf planet was not just an inert rock throughout its history. It was active, with processes that resulted in different materials in different regions. We are beginning to capture that diversity in our color images,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles.
The Dawn mission made history on March 6 as the first spacecraft to reach a dwarf planet, and the first spacecraft to orbit two extraterrestrial targets. Previously, Dawn studied giant asteroid Vesta from 2011 to 2012, uncovering numerous insights about its geology and history. While Vesta is a dry body, Ceres is believed to be 25 percent water ice by mass. By comparing Vesta and Ceres, scientists hope to gain a better understanding of the formation of the solar system.
Ceres’ surface is heavily cratered, as expected, but appears to have fewer large craters than scientists anticipated. It also has a pair of very bright neighboring spots in its northern hemisphere. More detail will emerge after the spacecraft begins its first intensive science phase on April 23, from a distance of 8,400 miles (13,500 kilometers) from the surface, said Martin Hoffmann, investigator on the Dawn framing camera team, based at the Max Planck Institute for Solar System Research, Göttingen, Germany.
The visible and infrared mapping spectrometer (VIR), an imaging spectrometer that examines Ceres in visible and infrared light, has been examining the relative temperatures of features on Ceres’ surface. Preliminary examination suggests that different bright regions on Ceres’ surface behave differently, said Federico Tosi, investigator from the VIR instrument team at the Institute for Space Astrophysics and Planetology, and the Italian National Institute for Astrophysics, Rome.
Based on observations from NASA’s Hubble Space Telescope, planetary scientists have identified 10 bright regions on Ceres’ surface. One pair of bright spots, by far the brightest visible marks on Ceres, appears to be located in a region that is similar in temperature to its surroundings. But a different bright feature corresponds to a region that is cooler than the rest of Ceres’ surface.
The origins of Ceres’ bright spots, which have captivated the attention of scientists and the public alike, remain unknown. It appears the brightest pair is located in a crater 57 miles (92 kilometers) wide. As Dawn gets closer to the surface of Ceres, better-resolution images will become available.
“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,” Russell said.
Both Vesta and Ceres are located in the main asteroid belt between Mars and Jupiter. The Dawn spacecraft will continue studying Ceres through June 2016.
Dawn’s mission is managed by NASA’s Jet Propulsion Laboratory, Pasadena, California, for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:
For more information about Dawn, visit: