- Geophysical Monograph Series
- Planetary Sciences | Science and Technology
- A geophysical planet definition
- IMPRS "Solar System School"
Research is carried out in the laboratory, from astronomical facilities throughout the world, and from spacecraft and landers. Studies involving small planetary bodies and near earth objects involve astronomy, and geology, modeling activities. Researchers in the field conduct those activities to learn about how planets form and also to identify objects in close proximity to earth.
Planetary habitability is at the center of astrobiology research at JPL. Researchers conduct field and lab studies in microbiology and chemistry to help them plan for future planetary exploration missions. Research in planetary atmospheres comprises a quantitative study of the atmospheres of major and minor bodies in the solar system and beyond. And then there's the troublesome issue of "neighborhood clearance". As has been emphasized by many who reject the IAU's definition, planets like Earth do not satisfy this qualification since new small bodies are constantly injected into planet-crossing orbits — i..
On top of that, this proposed definition seeks to resolve what is arguably one of the most regrettable aspects of the IAU's resolution.
Geophysical Monograph Series
I want to set straight in the mind of the public what a planet is. The IAU definition doesn't jive with my intuition and I find it doesn't jive with other people's intuition.
- The Authority of the Name of Jesus;
- Related Stories!
- Dragon Child (Prophecies Saga Book 1);
- Restricted elective courses!
The study was prepared for the upcoming 48th Lunar and Planetary Science Conference. This annual conference — which will be taking place this year from March 20thth at the Universities Space Research Association in Houston, Texas — will involve specialists from all over the worlds coming together to share the latest research findings in planetary science. Here, Runyon and his colleagues hope to present it as part of the Education and Public Engagement Event.
It is his hope that through an oversized poster, which is a common education tool at Lunar and Planetary Science Conference, they can show how this new definition will facilitate the study of the solar system's many bodies in a way that is more intuitive and inclusive. This is not the first time someone has proposed a definition other than the one proposed by the IAU. But few people have talked about education. They talk among their peers and little progress is made. I wanted to post this in a section to reach teachers. Naturally, there are those who would raise concerns about how this definition could lead to too many planets.
If intrinsic property of hydrostatic equilibrium is the only real qualifier, then large bodies like Ganymede, Europa, and the moon would also be considered planets. Given that this definition would result in a solar system with "planets", one has to wonder if perhaps it is too inclusive. However, Runyon is not concerned by these numbers. Why do we need a memorable number? How does that play into the definition? If you understand the periodic table to be organized based on the number of protons, you don't need to memorize all the atomic elements.
There's no logic to the IAU definition when they throw around the argument that there are too many planets in the solar system. Since its publication, Runyon has also been asked many times if he intends to submit this proposal to the IAU for official sanction.
Planetary Sciences | Science and Technology
To this, Runyon has replied simply:. Because the assumption there is that the IAU has a corner on the market on what a definition is. We in the planetary science field don't need the IAU definition. The definition of words is based partly on how they are used. If [the geophysical definition] is the definition that people use and what teachers teach, it will become the de facto definition, regardless of how the IAU votes in Prague. Regardless of where people fall on the IAU's definition of planet or the one proposed by Runyon and his colleagues it is clear that the debate is far from over.
Prior to , there was no working definition of the term planet; and new astronomical bodies are being discovered all the time that put our notions of what constitutes a planet to the test. The opportunity to study the Jovian system in unprecedented detail came courtesy of a gravitational assist for the Cassini spacecraft as it swept past Jupiter on 30 December The flyby at a distance of about 9. Cassini's observations began in early October and, apart from a short hiatus in mid-December, data was expected to be returned until well into March The interruption came when increased friction in one of the spacecraft's reaction wheels led to a temporary switch-over to hydrazine-fuelled thrusters.
Mission managers suspended imaging and other scientific observations that required pointing the spacecraft until 28 December. One of the most impressive observational efforts involved simultaneous studies of Jupiter's aurora from Cassini, Galileo and the Hubble Space Telescope, over two periods in December and January this year. The goal was to combine Cassini's measurements of the velocity, temperature, pressure, density and magnetic field direction of the solar wind with ultraviolet images obtained by the Space Telescope Imaging Spectrograph, in order to determine how the solar wind influences the giant planet's aurorae.
A geophysical planet definition
The Galileo spacecraft also participated in the campaign by taking measurements inside the magnetosphere. In addition, the January opportunity allowed the science teams to compare HST images of the day's ide aurora with images of Jupiter's night's ide aurora from Cassini. It was the first time that Jupiter's south-pole aurora had ever been imaged from the planet's night side.
These images support theories that the aurorae originate in electrical currents that connect Io and Jupiter along magnetic field lines.
MIMI enables scientists to see images of the planet's particle-filled magnetosphere and study its underlying dynamics. These images will eventually provide a large's cale look at the compression and expansion of the magnetosphere as it is buffeted by the solar wind. Then, when collisions with other particles provide them with an electron, they become neutral and are able to escape the magnetosphere.
And that's when we can detect them with our camera. More traditional imaging with Cassini's Imaging Science Subsystem captured many thousands of pictures of the cloud-covered planet, its dusky rings, and assorted satellites. One new picture — the best yet taken of the small moon Himalia — is the first to show one of Jupiter's outer moons as more than a star-like dot. Cassini was generally too far away to obtain high-resolution views of the four Galilean moons, but its instruments were able to obtain images as they passed through Jupiter's shadow.
Cassini shot the first movie ever made of the volcanic moon Io in eclipse, showing bright spots of hot lava and changes in auroral glows. This composite image captured by Cassini during the Millennium Jupiter Flyby shows, in true colours, Io and its shadow in transit against the disk of Jupiter. The spacecraft was Not to be outdone, the venerable Galileo turned its attention to searching for aurorae on Ganymede, the largest moon in the solar system, during the spacecraft's 29th orbit of Jupiter. The venerable orbiter's passage to within km of the moon's icy surface took place on 28 December , when Ganymede was traversing the shadow of Jupiter.
Other Cassini sequences revealed changing atmospheric conditions as the planet rapidly rotated. By comparing images of the same portion of the planet taken in daylight and darkness, it was possible to identify small areas that were producing lightning. Although Cassini approached almost along Jupiter's orbital plane, its imaging system could clearly distinguish the mottled cloud patterns near Jupiter's north pole compared with the latitudinal belts and zones nearer the equator.
Portions of Jupiter's ring system were also imaged by Cassini galileo. Even before the Jupiter Millennium Mission got under way, scientists had announced several startling new results.
Magnetic field readings taken by the Galileo spacecraft during a series of close approaches to Ganymede provided strong circumstantial evidence for the existence of liquid water under the surface. A thick layer of liquid, salty water beneath Ganymede's icy crust would be the best way to explain some of the data, according Margaret Kivelson, principal investigator for Galileo's magnetometer.
The evidence is more difficult to interpret than on Europa and Callisto since Ganymede has a strong magnetic field of its own, instead of just a secondary field induced by Jupiter's magnetism. However, Kivelson believes a melted layer several kilometres thick, beginning within km of Ganymede's surface, would fit the data if it was about as salty as Earth's oceans.
IMPRS "Solar System School"
In addition, infrared spectrometer studies of Ganymede suggest that, in the past, mineral-rich water may have emerged from below or melted at the surface, according to a study of infrared reflectance measured by Galileo. High-resolution images of Ganymede also hint at how the water or slushy ice may have surfaced through the fractured crust. Pictures taken as Galileo passed within km of Ganymede on 20 May reveal details of Arbela Sulcus, a relatively smooth, bright linear feature that may have formed by complete separation of Ganymede's icy crust. Studies indicate that natural radioactivity in Ganymede's rocky interior should provide enough heating to maintain a stable layer of liquid water between two layers of ice, about to km below the surface.
This contrasts with Europa, where interior tidal flexing caused by Jupiter's gravity provides much of the internal heat.