1. Describe the different kinds of planetary and satellite maps. Regarding the g
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Question
1. Describe the different kinds of planetary and satellite maps. Regarding the geological mapping of planets and satellites, what is a geological unit? Explain the three-fold system of geological classification used on planetary and satellite maps. What are the main geological system names on the Moon and Mars? (List these in order for both the Moon and Mars.) Describe the system of lettering that is used on planetary (and satellite) geological maps and explains the rationale of the lettering system. Give some examples.
2. Describe the nature and use of the principle of crater gradation in correlation. How is crater counting used in determining the age of planetary surfaces? What other ways do we have of determining the age of planetary surfaces? In other words, how can we apply relative age-dating principles from Earth to other planets? What is a T-junction on a geological map and what can it tell you about relative age?
3. Describe the structure of the outer solar system, including the Kuiper Belt and Oort cloud. Describe some of the objects and their orbits in the inner Kuiper Belt, including plutinos, KBOs, CKBOs, and others. Name and describe some KBOs. What are trojans and centaurs, where do they reside and where do they come from?
4. What is the geological history of the outer part of the solar system? How is the periodic activity or disturbance in the Oort cloud related to the structure and behavior of our galaxy? What length of the cycle is thought related disturbance in the Oort cloud? What are long-period comets and where do they come from?
Explanation / Answer
1. Planetary Maps is the map of solid objects outside of the Earth. Planetary maps can show any spatially mapped characteristic (such as topography, geology, and geophysical properties) for extraterrestrial surfaces.
Types of Planetary maps:
Satellite Maps are the maps created from satellite images captured by the satellites overhead in space.
Types of Satellite Maps available are: Google Maps, TerraServer; there are similar mapping tools from Microsoft and Yahoo, etc.
The three-fold system of geological classification used on planetary and satellite maps is Remote Sensing. Its the acquisition of information about an object or phenomenon without making physical contact with the object and thus in contrast to on-site observation. Remote sensing is used in numerous fields, including geography, land surveying and most Earth Science disciplines (for example, hydrology, ecology, oceanography, glaciology, geology); it also has military, intelligence, commercial, economic, planning, and humanitarian applications. n current usage, the term "remote sensing" generally refers to the use of satellite- or aircraft-based sensor technologies to detect and classify objects on Earth, including on the surface and in the atmosphere and oceans, based on propagated signals (e.g. electromagnetic radiation).
Geology system of Moon:
Highlands
Maria
Rilles
Domes
Wrinkle ridges
Grabens
Impact craters
Regolith
Lunar lava tubes
Geology system of Mars:
Equatorial canyon system
Chaotic terrain and outflow channels
Ice caps
Albedo features
Impact craters
2. One way to estimate the age of a surface is by counting the number of impact craters. This technique works because the rate at which impacts have occurred in the solar system has been roughly constant for several billion years. Thus, in the absence of forces to eliminate craters, the number of craters is simply proportional to the length of time the surface has been exposed. This technique has been applied successfully to many solid planets and moons .Crater counting is a method for estimating the age of a planet's surface. The method is based upon the assumptions that a new surface forms with zero impactcraters, and that impact craters accumulate at some constant rate. The method has been calibrated using the ages of samples returned from the Moon. Other techniques is radiometric dating
Another way to trace the history of a solid world is to measure the age of individual rocks. After samples were brought back from the Moon by Apollo astronauts, the techniques that had been developed to date rocks on Earth were applied to rock samples from the Moon to establish a geological chronology for the Moon. Scientists measure the age of rocks using the properties of natural radioactivity.
The T-junction is the form of cross cutting relation in a map just as it in cross section depending on the inclination of the planes with respect to the surface on which the juction is viewed. The T junction concept may be applied to depositional contacts between sedimentary rock units but also to the contacts between intrusions and other rock and by carbon dating or radioactive rating of the layers we can find the age of rocks.
3. Dynamical nomenclature in the outer solar system is complicated by the reality that we are dealing with populations of objects that may have orbital stability times that are either moderately short (millions of years or less), appreciable fractions of the age of the solar system, or extremely stable (longer than the age of the solar system). While the “classical belt” is loosely thought of as what early searchers were looking for (the leftover belt of planetesimals beyond Neptune), the need for a more precise and complete classification is forced by the bewildering variety we have found in the outer solar system.
The Kuiper belt is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune. It is similar to the asteroid belt, but is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region.
The Oort cloud is a theoretical cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 50,000 to 200,000 AU. It is divided into two regions: a disc-shaped inner Oort cloud (or Hills cloud) and a spherical outer Oort cloud. Both regions lie beyond the heliosphere and in interstellar space. The Kuiper belt and the scattered disc, the other two reservoirs of trans-Neptunian objects, are less than one thousandth as far from the Sun as the Oort cloud.
A classical Kuiper belt object, also called a cubewano is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axes in the 40–50 AU range and, unlike Pluto, do not cross Neptune’s orbit.
The name "cubewano" derives from the first trans-Neptunian object (TNO) found after Pluto and Charon, 15760 Albion, which until January 2018 had only had the provisional designation (15760) 1992 QB1.
Objects identified as cubewanos include:
Centaurs are small solar system bodies with a semi-major axis between those of the outer planets. They generally have unstable orbits because they cross or have crossed the orbits of one or more of the giant planets; almost all their orbits have dynamic lifetimes of only a few million years, but there is one centaur, which may be in a stable orbit. Centaurs typically behave with characteristics of both asteroids and comets.
The Trojan asteroids that we consider here are members of the population of objects that are coorbital with Jupiter. Mars is also known to have at least four coorbital asteroids, and the outer planets may have similar companions that have not yet been discovered thus expanding the original definition of a Trojan asteroid beyond those that are companions to Jupiter. There are two swarms of jovian Trojans, each consisting of a number of objects that librate about the L4 and L5 Lagrangian points in Jupiter’s orbit, 60° of heliocentric ecliptic longitude ahead and 60° behind the planet, and possessing sufficient dynamical stability to survive over the age of the solar system.
4. There are complex organic molecules in interstellar space, on interplanetary dust, in comets, and in the meteorites that hit the Earth from time to time. It makes good chemical sense that such compounds form naturally in interplanetary or interstellar space, because gas clouds, dust particles, and meteorite surfaces are bathed in cosmic and stellar radiation. But life as we know it consists of cells, composed mostly of liquid water that is vital to life. It is impossible to imagine the formation of any kind of water-laden cell in outer space; that could only have happened on a planet that had oceans and therefore an atmosphere.
Dust particles collide softly and tend to stick together by electrostatic and gravitational attraction in a process called accretion. "Dust bunnies" form under the bed in the same way. Around a new star, the dust bunnies can build up and compact into substantial solid masses a kilometer or so in diameter. Computer models show that in only a few million years, several thousand bodies the size of large asteroids will coalesce into larger units that we now see as planets. The new planets continue to be bombarded by asteroid-sized objects for perhaps several hundered million years in an era of huge impacts. Sometimes planets may have been shattered in huge impacts, or had fragments splintered off them into space. For example, a body larger than Mars may have hit the Earth just after it formed, knocking its axis into the present 23° tilt that gives us our seasons, and blasting debris into Earth orbit that quickly accreted to form the Moon. Around this time, our Solar System took on its present form, with three or four major terrestrial planets in stable orbits, giant gas planets orbiting outside them, and meteorites, asteroids, and comets still orbiting in space as celestial debris.
Recent studies have shown that the formation of the Oort cloud is broadly compatible with the hypothesis that the solar system formed as part of an embedded cluster of 200–400 stars. These early stars likely played a role in the cloud's formation, since the number of close stellar passages within the cluster was much higher than today, leading to far more frequent perturbations. Because the Oort Cloud is so much farther out than the Kuiper Belt, the region remained unexplored and largely undocumented. Space probes have yet to reach the area of the Oort cloud, and Voyager 1 – the fastest and farthest of the interplanetary space probes currently exiting the solar system – is not likely to provide any information on it.
For thousands of years, astronomers have watched comets travel close to Earth and light up the night sky. In time, these observations led to a number of paradoxes. For instance, where were these comets all coming from? And if their surface material vaporizes as they approach the sun (thus forming their famous halos), they must formed farther away, where they would have existed there for most of their lifespans.
In time, these observations led to the theory that far beyond the sun and planets, there exists a large cloud of icy material and rock where most of these comets come from. This existence of this cloud, which is known as the Oort Cloud (after its principal theoretical founder), remains unproven. But from the many short and long-period comets that are believed to have come from there, astronomers have learned a great deal about it structure and composition.
The outer Oort cloud may have trillions of objects larger than 1 km (0.62 mi), and billions that measure 20 kilometers (12 mi) in diameter. Its total mass is not known, but – assuming that Halley's Comet is a typical representation of outer Oort Cloud objects – it has the combined mass of roughly 3×1025 kilograms (6.6×1025 pounds), or five Earths.
Long-period comets are those comets which take more than 200 years to complete an orbit around the Sun and usually originate from the Oort Cloud. .
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