Is the Earth round?
The Earth is an irregularly shaped ellipsoid.
This NASA image shows Earth from space. The image is a combination of data from two satellites. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra satellite collected the land surface data over 16 days, while NOAA’s Geostationary Operational Environmental Satellite (GOES) produced a snapshot of the Earth’s clouds.
While the Earth appears to be round when viewed from the vantage point of space, it is actually closer to an ellipsoid. However, even an ellipsoid does not adequately describe the Earth’s unique and ever-changing shape.
Our planet is pudgier at the equator than at the poles by about 70,000 feet. This is due to the centrifugal force created by the earth’s constant rotation. Mountains rising almost 30,000 feet and ocean trenches diving over 36,000 feet (compared to sea level) further distort the shape of the Earth. Sea level itself is even irregularly shaped. Slight variations in Earth’s gravity field cause permanent hills and valleys in the ocean’s surface of over 300 feet relative to an ellipsoid.
Additionally, the shape of the Earth is always changing. Sometimes this change is periodic, as is the case with daily tides that affect both the ocean and the crust; sometimes the change is slow and steady, as with the drift of tectonic plates or the rebound of the crust after a heavy sheet of ice has melted; and sometimes the shape of the planet changes in violent, episodic ways during events such as earthquakes, volcanic eruptions, or meteor strikes.
The National Geodetic Survey measures and monitors our ever-changing planet. Geodesy is the science of measuring and monitoring the size and shape of the Earth, including its gravity field, and determining the location of points on the Earth’s surface.
https://oceanservice.noaa.gov/facts/earth-round.html
BIOLOGY
What is evolution and how does it work?
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Sub-topics (containing additional resources):
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 This in-depth, multi-part course takes you through evolutionary theory and mechanisms, from definitions to details, natural selection to genetic drift, mutations to punctuated equilibrium. |
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 Scientists use many different lines of evidence to reconstruct the evolutionary trees that show how species are related. This article is located within Evolution 101. |
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 Learn about the basic processes that have shaped life and produced its amazing diversity. This article is located within Evolution 101. |
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 Microevolution and macroevolution encompass change at very different scales, but both work through the same basic processes. |
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 Evolution is a fundamental concept in modern biology. Review the basics of how evolution works with a special focus on evidence and examples from the fossil record. This article appears at the American Geological Institute website. |
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 In lecture one of a four part series, evolutionary biologist Sean Carroll discusses Darwin and his two most important ideas: natural selection and common ancestry. This lecture is available from Howard Hughes' BioInteractive website. |
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 This tutorial on phylogenetics explains the basics of tree-thinking and provides many examples from real organisms. This resource is available from the Peabody Museum of Natural History |
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 This short video introduces basic concepts in phylogenetics and provides a model to help understand lineage-splitting. This resource is available from the Peabody Museum of Natural History |
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 This news brief from May 2009 explores the difference between phenotypic plasticity and evolutionary change in relation to the media's coverage of climate change. |
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 Phylogenetics has affected almost every area of biology - even the most basic one: how we classify organisms. Find out how phylogenetic classification works and what its advantages are. This article appears at SpringerLink. |
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 This website, which was produced to accompany an exhibit at the American Museum of Natural History, describes Darwin's life and how his ideas transformed our understanding of the living world. This article appears on the American Museum of Natural History website. |
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  This interview with MacArthur Fellow and paleobiologist, Geerat Vermeij, covers much ground, including adaptations in the mollusks he studies, evolutionary arms races, punctuated equilibrium, extinctions, macroevolution, and the value of diversity. |
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 The Ensatina salamander has been extensively investigated because it is a ring species — a species that demonstrates how geography and the gradual accumulation of genetic differences factor into the process of speciation. Biologist Tom Devitt continues the more than 50 years of Ensatina research by applying new genetic techniques and asking new questions about this classic evolutionary example. |
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 In a series of six lectures, scientists describe how evolutionary theory makes contributions to the field of human health through studies of the human genome, physiology, lifestyle, and interaction with the environment. This resource appears at the National Evolutionary Synthesis Center website. |
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 Many disciplines within biology (and many basic biology texts) have come to depend on evolutionary trees. Get the basics you need to understand and interpret these key diagrams. This article appears at SpringerLink. |
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 Learn about phylogenetic systematics, the study of the evolutionary relationships among organisms, and how the field is shaping biological research today. |
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 Tree thinking, or phylogenetics, is an important way of understanding evolutionary relationships. Reading trees correctly can pose some challenges. This video introduces the basics of three reading and addresses common problems in tree reading. This resource is available from the National Evolutionary Synthesis Center |
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 In the this interactive video, college students guide viewers through problems on phylogenetics and address some of the misconceptions that many students have with the subject. This resource is available from the National Evolutionary Synthesis Center |
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 This news brief, from February 2012, describes the discovery of hybrid sharks in Australian waters, debunks some common misconceptions regarding the discovery, and examines the possible evolutionary trajectories of these animals. |
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 This news brief, from November 2012, describes what a new dinosaur fossil from North America has to tell us about the evolution of feathers. |
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 ¿Qué es la evolución y cómo funciona? Introducción a la evolución ofrece información detallada y práctica sobre los patrones y los mecanismos de la evolución. |
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 This news brief from October 2013 describes the discovery of four new species of legless lizard. Why don't we just call these animals snakes? Because of their evolutionary history... |
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 This excerpted chapter from Carl Zimmer's book, The Tangled Bank, describes the evolutionary processes responsible for large scale patterns in the diversity of life through time. Reprinted with the permission of Roberts and Company Publishers, Inc. This resource is available from the National Center for Science Education. |
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 This pamphlet with self-quizzes provides students with a self-paced tutorial in tree thinking and corrects many common misconceptions about phylogenetic trees. |
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 Print this 28x36" poster for your classroom wall. For ideas about how to use the poster in your class, visit Two- and Ten-minute Trees. |
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 Print this 18x24" poster for your classroom wall. For ideas about how to use the poster in your class, visit Two- and Ten-minute Trees. |
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 Print this 28x36" poster for your classroom wall. For ideas about how to use the poster in your class, visit Two- and Ten-minute Trees. Source:https://evolution.berkeley.edu/evolibrary/search/topics.php?topic_id=13 |
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