DOCSLIB.ORG

UE Classroom Chronicles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
UE Classroom Chronicles UE Classroom Chronicles Edition 1 May 21, 2021 Space Race: The USSR took the lead launching Hunters in the Sky the un-manned spacecraft known by: Jackson Griffin USA vs USSR as “Luna.” The first man-made by: Colin Dignan object on the moon was Luna 2; Who would have thought that the first spacecraft to carry High stakes go to a high place! birds of prey can differ so greatly humans to the moon was Apollo from each other? Birds of prey The space race was a race during 11. the Cold War. It was a race to have advanced hunting techniques that help them to space! The Cold War was a time The USSR cleared the first when political relations between survive. They have slight important hurdles. They anatomical differences or the US and USSR were tense, successfully landed the first man- extremely tense. The space race adaptations to help them survive made object on the moon (Luna and have a successful hunt. was about the USSR and US racing 2). They also took the first to get a spacecraft on the moon. pictures of the far side of the “With their hooked beaks, Kennedy set a challenge to land a moon (Luna 3) and the first soft curved talons, and superb human on the moon because the landing on the moon (Luna 9). eyesight, eagles, and birds of USSR had beat the US to get a The USSR launched Luna 10 as prey are born to kill” machine on the moon. During the well, which orbited the moon. The -David Burnie space race the USSR launched a machines in the space race took spacecraft named Luna. The way that birds of prey hunt is the lead, though the humans were important to understand how they about to catch up with the Apollo live. Some most common forms of spacecraft mission. hunting are still hunting, scavenging, and fishing. Most The Apollo missions were trying to raptors in wooded areas “still land humans on the moon. Apollo hunt”. They sit on a perch and 1 was a catastrophic failure which watch until prey comes near them caused three astronauts to, sadly, and then catch and kill it with pass away. This was a huge their claws. setback for the Apollo program. Still, the Apollo missions continued. Apollo 8 were the first humans to directly see the far side of the moon through their The space race was a race spacecraft. Apollo 10 tested between the USSR and the US. everything apart from the The space race was when the landing. Apollo 11, was the first USSR and US tried to complete spacecraft to land a human on the important space goals before the moon. other. Spirit Week – “That’s one small step for man, Tuesday, June 1st one giant leap for mankind.” Twin Tuesday - Dress like a -Neil Armstrong friend from your class. Page 1 Continued on Next Page Edition 1 May 21, 2021 Many raptors in open country Things You Might Not areas hunt by flying high above You also don’t want a wheel that's the ground, watching it till they Know About too big or too small. If they have spot prey and then they swoop Hamsters a wheel that's too small they will down to catch it. Ospreys and fish by: Jane Jarvis badly hurt their spine. If it’s too eagles are perfectly adapted to big the wheel won’t turn as well catch fish. Their talons are curved If you don't know what hamsters and the hamster won’t get enough more than other birds of prey. are, they are small rodents with exercise. They fly high above the water to over 20 different species in the spot the fish, then swoop down. hamster family. Wild hamsters Would You Want to are found in Europe and Asia. Vultures are scavengers, and fly They have a very short life span Live Without Bees? by: Elena Calsyn high around the area to spot of 2 - 3 years. Yes, they can bite! carrion, dead prey, to feed on. They have tiny teeth that draw Did you ever think that it would They have strong beaks to tear at lots of blood when they bite you. bee a disaster with no bees in this the carcasses. It is thought that if world? Just think about it. I a black vulture finds a carcass with understand you might be thinking meat too tough to tear into, it will that bees sting and are lead a king vulture to the carcass, aggressive, but they are so much and then let the king vulture do more than that! the work. “One out of three bites of food “Many open-country raptors eaten worldwide depends on hunt by flying high, surveying a pollinators, especially bees, for a wide area, then swooping fast” successful harvest” - Elizabeth Grossman Few bird species work together, There are some things you Without bees it would definitely but those that do can take down probably didn't know about be a disaster! Obviously we much bigger prey than one bird hamsters. First of all, male wouldn’t have honey, but we could do on its own. For those that hamsters are friendlier than would lose a lot of other foods hunt in groups, one bird swoops females. If you are wanting to produced by plants. Around half down and scares the bird out of handle a hamster, a male is a of the fruits and vegetables we cover, then the others kill it while better choice. Some foods that love would disappear. Not only it’s in the open. Some birds steal can kill hamsters are: chips, that, but we would also lose the from others as well as hunting for chocolate, bread, sweets, pasta, animals that eat those plants, and themselves. This is called pirating. biscuits, dairy products, and most even the animals that eat those They fly upside-down underneath house and garden plants. animals! “Bees are flying insects their target, and grab the prey. Hamsters bite their cages because that are closely related to wasps Birds of Prey are specifically they are either bored or to wear and ants,” says author and adapted hunters and have many down their teeth, unlike humans researcher Alex Woolf. Most bees techniques that help them survive. their teeth grow nonstop, and if however, are not aggressive and their teeth are too big it could are actually very peaceful when cause a serious infection. not threatened. Honeybees die Spirit Week – when they sting, because when Wednesday, June 2nd "I'm done with men. I have a they try to fly off, some of their Wacky Wednesday – Bring hamster. That's all I need." abdomen rips off, killing them. out your wacky clothes, - Janet Evanovich socks, hats and hair. Page 2 Continued on Next Page Edition 1 May 21, 2021 In order to make honey, first the “Beehive fences are used in Africa In 1969, on July 20th (on one half bee takes the nectar back and to keep elephants from trampling of the world) and July 21st (on the regurgitates it back into another farmland,” says Mr. Woolf, “fields other half), almost a billion people bee's mouth. “A bee’s tongue is are surrounded by beehives hung on Earth clicked on their TVs, covered with little hairs that from wires. If an elephant touches eagerly waiting to watch as Apollo extend outwards to catch the a wire, the bees come out, which 11 would attempt to put men on nectar. Then the bee sucks back in drives the elephant away.” A the moon for the first time in the tongue with the nectar on it, beehive fence is a little bit like an history. Just think about it for just and it does that in less than a electric fence, but it’s cheaper, it a second. In that time nobody had second.” says Alex Woolf, “Then doesn't hurt the elephants, it ever walked on the moon before! the nectar is turned into honey by reduces the chance of elephants It was a long, long march to that bees chewing it, swallowing, and being killed by farmers because of day. Many people were waiting for regurgitating it over and over.” trampled crops, and pollinators the launch of Apollo 11 and now Honeybees produce beeswax from and honey come with it. We can they were ready. At 9:32 am . their abdomens, which they use to help bees by planting bee- WOOSH off they went! build the honeycomb. People melt friendly flowers, vegetables, fruit, that wax and turn it into things like and herbs. These include lilac, candles. We can also use this lavender, wisteria, squash, beeswax to coat a piece of fabric honeysuckles, pumpkin, and and wrap it around food, like a sunflowers. Ask if you can put a half- eaten avocado for example, bee nest in your garden. It will to keep it fresh. give solitary bees somewhere to spend the Winter. “A world without bees would be pretty grim,” concludes Alex Woolf. “So many of the fruits and vegetables we enjoy wouldn’t exist without the pollinating “The eagle has wings!” efforts from bees.” As much as we -Neil Armstrong do know about bees that makes Neil Armstrong radioed as he and us treasure them, there may be Buzz Aldrin flew 69 miles above more that we can still learn from the moon. “You are a go for these amazingly busy, intelligent, PDIC.” (Powered Descent When the honey is finally ready, and selfless insects as well as the Ignition) Mission Control radioed the bees seal the cell with a wax complex world of the beehive.
Load more

Recommended publications
  • Download This Article in PDF Format
    A&A 614, A15 (2018) https://doi.org/10.1051/0004-6361/201731644 Astronomy & © ESO 2018 Astrophysics Mutual event observations of solar system objects by SRC on Mars Express? Analysis and release of observations R. Ziese1 and K. Willner2 1 Technische Universität Berlin, Institute of Geodesy and Geoinformation Science, Str. des 17. Juni 135, 10628 Berlin, Germany e-mail: [email protected] 2 German Aerospace Center (DLR), Institute of Planetary Research, Rutherfordstr. 2, 12489 Berlin, Germany e-mail: [email protected] Received 25 July 2017 / Accepted 21 January 2018 ABSTRACT Context. Both Martian moons, Phobos and Deimos, have been observed during several imaging campaigns by the Super Resolution Channel (SRC) on the Mars Express probe. Several tens of images are obtained during mutual event observations – when the Martian moons are both observed or together with another solar system body. These observations provide new opportunities to determine the bodies’ positions in their orbits. Aims. A method was sought to automate the observation of the positions of the imaged bodies. Within one image sequence a similarly accurate localization of the objects in all images should be possible. Methods. Shape models of Phobos and Deimos are applied to simulate the appearance of the bodies in the images. Matching the illuminated simulation against the observation provides a reliable determination of the bodies’ location within the image. To enhance the matching confidence several corrections need to be applied to the simulation to closely reconstruct the observation. Results. A list of 884 relative positions between the different objects is provided through the Centre de Données astronomiques de Strasbourg (CDS).
    [Show full text]
  • The Formation of the Martian Moons Rosenblatt P., Hyodo R
    The Final Manuscript to Oxford Science Encyclopedia: The formation of the Martian moons Rosenblatt P., Hyodo R., Pignatale F., Trinh A., Charnoz S., Dunseath K.M., Dunseath-Terao M., & Genda H. Summary Almost all the planets of our solar system have moons. Each planetary system has however unique characteristics. The Martian system has not one single big moon like the Earth, not tens of moons of various sizes like for the giant planets, but two small moons: Phobos and Deimos. How did form such a system? This question is still being investigated on the basis of the Earth-based and space-borne observations of the Martian moons and of the more modern theories proposed to account for the formation of other moon systems. The most recent scenario of formation of the Martian moons relies on a giant impact occurring at early Mars history and having also formed the so-called hemispheric crustal dichotomy. This scenario accounts for the current orbits of both moons unlike the scenario of capture of small size asteroids. It also predicts a composition of disk material as a mixture of Mars and impactor materials that is in agreement with remote sensing observations of both moon surfaces, which suggests a composition different from Mars. The composition of the Martian moons is however unclear, given the ambiguity on the interpretation of the remote sensing observations. The study of the formation of the Martian moon system has improved our understanding of moon formation of terrestrial planets: The giant collision scenario can have various outcomes and not only a big moon as for the Earth.
    [Show full text]
  • Editorial Manager(Tm) for Earth, Moon, and Planets Manuscript Draft
    Editorial Manager(tm) for Earth, Moon, and Planets Manuscript Draft Manuscript Number: MOON491 Title: Irregularly Shaped Satellites-Phobos & Deimos- moons of Mars, and their evolutionary history. Article Type: Manuscript Keywords: gravitational sling shot effect; Clarke's Orbits; Roche's Limit; velocity of recession/approach; sub-synchronous orbit; extra-synchronous orbit. Corresponding Author: DOCTOR BIJAY KUMAR SHARMA, Ph.D Corresponding Author's Institution: NATIONAL INSTITUTE OF TECHNOLOGY First Author: Bijay K Sharma, B.Tech,MS & Ph.D. Order of Authors: Bijay K Sharma, B.Tech,MS & Ph.D.; BIJAY KUMAR SHARMA, Ph.D Abstract: Phobos, a moon of Mars, is below the Clarke's synchronous orbit and due to tidal interaction is losing altitude. With this altitude loss it is doomed to the fate of total destruction by direct collision with Mars. On the other hand Deimos, the second moon of Mars is in extra-synchronous orbit and almost stay put in the present orbit. The reported altitude loss of Phobos is 1.8 m per century by wikipedia and 60ft per century according to ozgate url . The reported time in which the destruction will take place is 50My and 40My respectively. The authors had proposed a planetary-satellite dynamics based on detailed study of Earth-Moon[personal communication: http://arXiv.org/abs/0805.0100 ]. Based on this planetary satellite dynamics, 2 m/century approach velocity leads to the age of Phobos to be 23 Gyrs which is physically untenable since our Solar System's age is 4.567Gyrs. Hence the present altitude loss is assumed to be 20 m per century.
    [Show full text]
  • Mars Orbiter and Lander (ESA)
    So much nonsense has been written about the planet … that it is easy to forget that Mars is still an object of serious scientific investigation. Canadian astronomer Peter M. Millman, in “Is There Vegetation on Mars,” The Sky, 3, 10–11 (1939) Tentative Course outline • Today: Intro to Mars, Early discoveries about Mars (Chapters 1-4) • Oct 17: Canals on Mars, Water on Mars (Chapters 5-8) • Oct 24: Lichens on Mars (Chapter 9) • Oct 31: Viking mission (Chapter 10) • Nov 7: ALH 84001 (Chapter 11) • Nov 14: Methane on Mars (Chapters 12-15) Earth and Mars Basic Facts Earth Mars • 93 million miles from • 142 million miles from sun sun • Diameter: 4,212 miles • Diameter: 7,918 miles (53% of Earth) • Orbit: 365.25 days • Mass: 10.7% of Earth • Solid surface • Orbit: 687 days • Thin atmosphere • Solid surface • Thin atmosphere • 1 big moon • 2 little moons Basic Facts about Earth and Solar System • Sun and planets formed at same time The Nebular Hypothesis Immanuel Pierre Kant Laplace 1755 1796 sun (center) and planets (in disk) form at same time out of rotating cloud that collapses under the force of gravity An ALMA image of the star HD 163296 and its protoplanetary disk as seen in dust. New observations suggested that two planets, each about the size of Saturn, are in orbit around the star. These planets, which are not yet fully formed, revealed themselves in the dual imprint they left in both the dust and the gas portions of the star's protoplanetary disk. Credit: ALMA (ESO/NAOJ/NRAO), Andrea Isella, B.
    [Show full text]
  • Hall: a Phobos and Deimos Sample Return Mission
    41st Lunar and Planetary Science Conference (2010) 1633.pdf HALL: A PHOBOS AND DEIMOS SAMPLE RETURN MISSION. Pascal Lee1,2,3, Joseph Veverka4, Julie Bel- lerose5, Marc Boucher1, John Boynton6, Stephen Braham1,7, Ralf Gellert8, Alan Hildebrand9, David Manzella10, Greg Mungas6, Steven Oleson10, Robert Richards11, Peter C. Thomas4, and Michael D. West1,12. 1Mars Institute, 2SETI Institute, 3NASA Ames Research Center, [email protected], 4Cornell Univ., 5Carnegie Mellon Univ. 6Firestar Engineering, 7Simon Fraser University, 8Univ. of Guelph, 9Univ. of Calgary, 10NASA Glenn Research Cen- ter, 11Optech, 12The Australian National Univ. Introduction: Hall is a proposed NASA-led inter- types of primitive asteroids, but their surfaces also national robotic lander and sample return mission present lateral variations in albedo and color, suggest- (SRM) to explore and return samples from the two ing possible variations in the composition and/or moons of Mars, Phobos and Deimos. The mission will weathering state of their regolith. address the outstanding issues of the origin, nature, and Samples from Phobos and Deimos, if they were to evolution of both Phobos and Deimos, as well as pro- include soils as well, would allow detailed investiga- vide unique insights into early solar system processes, tions of the nature and evolution of their regolith. In planetary formation, and the evolution of Mars itself. this regard, an intriguing prospect is that their regolith Hall is being developed as a New Frontiers-class mis- should include meteoritic signatures from Mars [7-9, 11], asteroids, comets, and interplanetary dust particles sion and will use solar electric propulsion. Hall is (IDPs). Sampling Phobos’s regolith could therefore named after American astronomer Asaph Hall who, in provide access to a wide variety of martian and other 1877, discovered the two moons of Mars.
    [Show full text]
  • Mars Mars Is the Fourth Planet from the Sun. the Planet
    Mars Mars is the fourth planet from the sun. The planet is one of Earth's "next- door neighbors" in space. Earth is the third planet from the sun, and Jupiter is the fifth. Like Earth, Jupiter, the sun, and the remainder of the solar system, Mars is about 4.6 billion years old. Mars is named for the ancient Roman god of war. The Romans copied the Greeks in naming the planet for a war god; the Greeks called the planet Ares (AIR eez). The Romans and Greeks associated the planet with war because its color resembles the color of blood. Viewed from Earth, Mars is a bright reddish-orange. It owes its color to iron-rich minerals in its soil. This color is also similar to the color of rust, which is composed of iron and oxygen. The planet Mars, like Earth, has clouds in its atmosphere and a deposit of ice at its north pole. But unlike Earth, Mars has no liquid water on its surface. The rustlike color of Mars comes from the large amount of iron in the planet's soil. Image credit: NASA/JPL/Malin Space Science Systems Scientists have observed Mars through telescopes based on Earth and in space. Space probes have carried telescopes and other instruments to Mars. Early probes were designed to observe the planet as they flew past it. Later, spacecraft orbited Mars and even landed there. But no human being has ever set foot on Mars. Scientists have found strong evidence that water once flowed on the surface of Mars.
    [Show full text]
  • Wisconsin at the Frontiers of Astronomy: a History of Innovation and Exploration
    Feature 2 Article Wisconsin at the Frontiers of Astronomy: A History of Innovation and Exploration Collage of NASA/Hubble Images (NASA/Hubble) 100 Wisconsin Blue Book 2009 – 2010 Wisconsin at the Frontiers of Astronomy: A History of Innovation and Exploration by Peter Susalla & James Lattis University of Wisconsin-Madison Graphic Design by Kathleen Sitter, LRB Table of Contents Introduction ...........................................................................................................101 Early Days ...................................................................................................................102 American Indian Traditions and the Prehistory of Wisconsin Astronomy ...................................................................... 102 The European Tradition: Astronomy and Higher Education at the University of Wisconsin .........................105 The Birth of the Washburn Observatory, 1877-1880 ....... 106 The Development of Astronomy and Scientific Research at the University of Wisconsin, 1881-1922 .....110 The Growth of Astronomy Across Wisconsin, 1880-1932 ..........................................................................................................120 The New Astronomy.......................................................................................123 The Electric Eye ..............................................................................................123 From World War II and Into the Space Age ............................131 A National Observatory ..........................................................................136
    [Show full text]
  • An Abstract of the Dissertation Of
    AN ABSTRACT OF THE DISSERTATION OF Emily M. Simpson for the degree of Doctor of Philosophy in History of Science presented on June 12, 2018. Title: Mars and Popular Astronomy, 1890-1910 Abstract approved: ______________________________________________________________________ Jacob D. Hamblin Beginning in the late-nineteenth century, several dialogues emerged concerning life on Mars. Some supported the notion of an inhabited Mars, citing recent observations of the planet, while others, pointing to a lack of concrete evidence, denied the validity of such a bold hypothesis. The dialogues within and between different groups focused on three primary topics: the existence of artificial canals on Mars, evaluation of scientific values, and methods to contact Mars from Earth. Scientists and science popularizers recognized the power of popular media to legitimate and perpetuate their interpretations of Mars and employed several tools to promote their ideas, especially when those ideas proved controversial. These methods were the use of environmental conditions as scientific authority, the creation of popular public identities, and promotion of the power of technology to discover hidden truths of the universe. Mars and Popular Astronomy draws upon resources in several manuscript and correspondence collections from archives housed at Lowell Observatory, Caltech, Huntington Library, and University of California, Santa Cruz. This study also relies on contemporary newspapers and popular magazines. When pieced together, these documents reveal the tactics that scientists and science popularizers used in their efforts to define, create, and control popular science. They also show how competing interests overlapped and how participants in the debates grappled with definitions of scientific authority and the parameters for responsibility and accountability in science communication.
    [Show full text]
  • Biographical Memoir of Asaph Hall*
    BIOGRAPHICAL MEMOIR ASAPH HALL 1829-1907 GEORGE WILLIAM HILL READ HEI-OIIK THE NATION.\I, ACADEMY OF SCIENCES AI-KH> 2:>, loos (25) 241 BIOGRAPHICAL MEMOIR OF ASAPH HALL* Tn commencing the story of a remarkable man of science, it is necessary to say something of his lineage, in spite of the gener- ally held opinion that the details of genealogy make dry read- ing, f ASAPH HALL undoubtedly descended from John Hall, called of New Haven and Wallingford to distinguish him from the other numerous John Halls of early New England (Savage makes no less than seven before 1660), and who arrived at New Haven shortly after June 4, 1639, as he is one of the after-signers of tlie New Haven Planters' Covenant. His movements before his arrival are in some obscurity. From his son Thomas of Wal- lingford receiving a grant of fifty acres of land from the General Court of the Colony at the session of October, 1698, "In consid- eration of his father's services in the Pequot war," it is inferred that he was a dweller in the colony in 1637. At this date there were only four settlements in Connecticut, and it is supposed that the John Hall of New Haven is identical with a John Hall who appears as the holder of lots in Hartford about 1635. The genealogists arc in dispute in the matter. Mr. Shepard sums up thus: John Hall came with the advance Hooker party, in 1632, or perhaps on the Griffin or the Bird (two vessels whose arrival at Massachusetts Bay is mentioned by Winthrop), September 4, 1633.
    [Show full text]
  • Antigravity and Antigravitational Forces
    A n t i g r a One hundred years ago, Albert Einstein came up with a new theory of v i t gravitation. Later he added to his field equations the cosmological y constant which is accountable for the accelerated expansion of the universe. Thus a natural question arises concerning what is the energy source for this expansion. This monograph is about the novel concept of antigravity and antigravitational forces. We present various observational arguments showing the expansion on small cosmological scales. In particular, the Solar system and single galaxies expand at a rate comparable to the Hubble constant. The novelty of our ideas is that traditionally the expansion of the universe according to Edwin Hubble has been assumed to take place only between galaxies. The boldness of our approach is that it points to a weak violation of the law of conservation of energy. We claim that any system of free bodies that interact gravitationally with delays expands on average. We suggest that this is due to gravitational aberration effects resulting from a finite speed of gravity. Our book should be especially useful for scientists who look for the origin of dark matter and dark energy. Michal Křížek Filip Křížek Lawrence Somer Michal Křížek is a senior researcher at the Institute of Mathematics of the Czech Academy of Sciences and Professor at Charles University. Filip Křížek is a junior researcher at the Nuclear Physics Institute of the Czech Antigravity - Its Origin and Academy of Sciences. Lawrence Somer is Professor of Mathematics at the Catholic University of America in Washington, D.C.
    [Show full text]
  • Corn Mars Moons.Pmd
    Planetary exploration Spaceflight Vol 47 May 2005 Mapping the moons of Mars: Phobos and Deimos by Philip Corneille Since antiquity, the planet Mars has always been an object of great interest to observers of the night sky. However, the two tiny moons of the red planet weren’t discovered until the 1877 Mars opposition and it took another century to get some good photographs of these enigmatic satellites. Moreover, mapping both Martian moons proved very difficult due to their potato-shaped surfaces. The satellites of Mars Since Galileo Galilei (1564-1642) made the 18 August 1877 put beyond doubt the first telescopic observations of the planets in character of these objects and the discovery the solar system in 1610, astronomers was publicly announced by US Navy Admiral started to speculate about the moons of Rodgers. Of the various names that were Mars. Galileo’s observations revealed that proposed, Hall chose the suggestion by Jupiter, the next planet beyond Mars, had Henry Madan (1838-1901) of Eton college; four satellites. Johannes Kepler (1571-1630), Deimos for the outer moon and Phobos for a believer in the harmonic numerology of the the inner moon. In Greek mythology, Phobos solar system, argumented that in order out of and Deimos were the horses drawing the the Sun, Venus had no moons, Earth had chariot of Mars, the god of war. The Romans one, Mars was uncertain and Jupiter was called Phobos ‘Pavor’ and Deimos ‘Pallor’. In thought to have four. Two moons for Mars 1879, Hall was presented with the Gold seemed the proper assumption to fit the Medal of the Royal Astronomical Society of any new satellites was made on 19 pictures mathematical progression.
    [Show full text]
  • The Crustal D Ichotom Y on Mars 1991 1
    The Crustal Dichotomy On Mars A Thesis submitted for the Degree of Doctor of Philosophy of the University of London by Cordula Astrid Robinson UCL University of London Observatory Annexe Department of Physics & Astronomy University College London University of London 1991 1 ProQuest Number: 10611114 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10611114 Published by ProQuest LLC(2017). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 Abstract The crastal dichotomy is the term used for the surface division of Mars into a lightly- cratered third of the planet, in the middle to upper latitudes of the northern hemisphere, and a remaining heavily-cratered two-thirds. The lightly-cratered third stands approximately 3 km lower than the heavily-cratered surface. Established explanations for the crustal dichotomy consider it a stable feature that orig­ inated early in the planet’s history either by endogenic means (in the form of catastrophic overturn of the mantle, probably associated with core formation) or by exogenic means (either in the form of a giant single impact or the focusing of several large impacts).
    [Show full text]