Imagining Other Earths from Coursera

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Syllabus

Introduction

This short lecture introduces Professor Spergel, the basic outline of the course and its goals.

The Universe is Big!

One of the most striking features of the universe is its enormous size. The lecture discusses the structure of our Solar System, the new dwarf planets, and the distance to the nearest stars. The lecture then moves outwards to the scales of our galaxy and the visible universe.

What is Life?

This lecture introduces different approaches to defining life, a necessary step if we are going to search for life. We then introduce the basic building blocks of biochemistry. One potential way of detecting life is through its byproducts like Methane. We discuss efforts to discuss life on Mars.

Why is Mercury Hot?

This lecture uses energy balance to determine the effective temperature of planets. The lecture introduces the idea of temperature, black body spectrum and luminosity. We then calculate the location of the habitable zone, the range of distances where planets are likely to have liquid water.

Snowball Earth

Planet temperatures depend on the albedo of the planet (its reflectivity) and the transparency of its atmosphere. This lecture introduces the basic physics behind global warming, discusses how non-linear feedbacks can exacerbate its effects, and describes how variations in the Earth’s albedo (mostly due to snow) can produce “Snowball Earth” episodes, extended epochs during which the Earth was mostly covered with ice.

Planetary Atmospheres

This lecture begins by introducing the basic physics of gases, liquid and solids. The lecture then describes how the balance between gas pressure and gravity shapes the structure of planetary atmospheres.

Mercury and Venus

This lecture discusses some of the remarkable properties of the two innermost planets, Mercury and Venus. We discuss how Mercury, a very hot planet, can have ice at its poles. We describe its surprisingly strong magnetic field. We discuss the structure of Venus’s atmosphere and how a “runaway greenhouse effect” made its surface uninhabitable.

Mars

Mars may be the other planet in the Solar System that hosts life. This lecture introduces the basic properties of Mars, Mars’ atmosphere and its seasons. We discuss Martian exploration, the search for water and methane on Mars and potential signature of life. Seasons.

The Moon

By studying the properties of the Moon, we learn not only about its history but about the formation history of the Earth. This lecture discusses the physics of craters and the tidal interactions between the Earth and the Moon. We then apply the physics of tides to see how it shapes the properties of planets around M stars.

Small Bodies of the Solar System

This lecture begins by discussing comets and asteroids, remnants of the formation of our Solar System. We discuss how collisions of comets and asteroids with Earth have shaped its history. The lecture then discusses the moons of Jupiter and Saturn—these moons have complex geologies and atmospheres. Some of the moons may be potentially habitable by life forms.

Kepler’s Law and Search for Extrasolar Planets

This lecture shows how Kepler’s Law, the relation between a planet’s Period and the radius of its orbit, can be understood in terms of the physics of gravity. We then see how we can use observations of star’s motions (and Kepler’s Law) to detect extrasolar planets and determine their basic properties.

Kepler and Transits

Transits have been an important event for astronomy for over 400 years. This lecture describes the transit of Venus and how it was used to measure the size of our Solar System. This lecture then discusses how NASA’s Kepler mission observes planetary transits and how its observations have shaped our understanding of the properties of extrasolar planetary systems.

Einstein and the Search for Planets

Einstein’s theory of General Relativity tells us that mass curves space and deflects light. Thus, observations of light deflection can tell us about the distribution of mass. Microlensing observations use this effect to detect planets around distant stars. We discuss how these observations have shown us that planets are as common as stars and imply the existence of “orphan planets”, planets that were ejected by their Suns and are now wandering the Galaxy.

Properties of Stars

Stars are remarkably simple objects: their mass and age determine the basic properties. This lecture discusses how we determine the distance and luminosity of stars and how this relates to the Star’s size and temperature.

Stellar Evolution

Like planets, the structure of stars are shaped by the balance between gravity and pressure. Nuclear fusion, the energy source at the star’s interior, converts Hydrogen to heavier elements. This lecture introduces these concepts and shows how nuclear burning drives the evolution of stars.

Quantum Mechanics and Fingerprinting Planets

This lecture introduces the Pauli exclusion principle, which requires that only one electron can be in any state. We use this principle to understand the properties of materials and the atomic lines seen in planetary and stellar structure.

Optics and Imaging Planets

This lecture introduces the basic of optics, explains how lenses and telescopes work, and then discusses the challenges of imaging planets around bright stars.

Formation of the Earth and the Origin of Water

This lecture discusses the physics of star and planet formation. Because of the conservation of angular momentum, collapsing gas clouds form disks that then fragment to eventually form planets. We observe a tremendous diversity of planetary systems which implies that planets, unlike Stars, have a much wider range of properties.

Biochemistry of Life

This lecture discusses the building blocks of life. We focus first on the importance of water as a medium for life and then discuss how amino acids are the building blocks of complex proteins. We then discuss the role of RNA and DNA in reproduction and protein synthesis.

Is Earth Special? Origin of Life

This lecture describes our efforts to understand the origin of life on Earth. While it is relatively easy to synthesize amino acids, we do not yet understand how this building blocks are assembled into complex cells. The lecture ends with an exploration of the speculation that life originated outside Earth.

Evolution of Life

The basic principles of evolution (selection, mutation, and heritability) do not depend on the details of biochemistry. Thus, we can expect evolutionary principles to apply in extrasolar life. We discuss the role of sex in evolution and discuss how we can use the Tree of Life to study life’s origins.

Extremophiles

Extremophiles are life forms that flourish in extreme environments—regions of very high (or low) temperatures, acidities, and even intense radioactivity. The lecture describes some of these fascinating life forms including the bacterial mats of Yellowstone and Deinococcus Radiodurans, the toughest creature on Earth. These extremophiles inform our understanding of astrobiology.

Extinctions

There have been at least 5 mass extinctions in the Earth’s history. These extinctions were events that wiped out most of life on the planet and drove a large fraction of all life forms into extinction in a very short period of time. The most famous of these extinctions “killed’” the dinosaurs when an asteroid hit the Yucatan. We are in the midst of the sixth extinction due to human induced changes in the environment.

What makes a Habitable Planet?

This lecture discusses some of the requirements for habitability. We discuss the faint Sun problem—the ancient Sun was much colder yet the Earth was still habitable and discuss the range of planetary systems that might be able to host life. We conclude by describing plans to use the James Webb Space Telescope, the successor to the Hubble Telescope, to find signs of life.

Habitable Zone, Fermi Paradox & SETI

The final lecture discusses the search for technologically advanced life in the Galaxy. We describe the “Fermi Paradox”: if technologically advanced life is common, then it would have long ago spread through the Galaxy. Thus, we might have expected to have already encountered life. This lecture ends by contemplating “why aren’t they here?”

Good to know

Know what's good

, what to watch for

, and possible dealbreakers

Speculates about the existence of extraterrestrial life, fostering imagination and critical thinking

Presents a comprehensive overview of astronomy, biology, and planetary science, providing a broad foundation

Taught by Professor David Spergel, a renowned astrophysicist and Nobel laureate, adding credibility and value

Introduces core scientific concepts essential for understanding the search for extraterrestrial life

Provides a free and accessible learning experience, removing financial barriers for curious learners

Does not offer a certificate upon completion, which may limit its value for professional development

Reviews summary

Astronomy for everyone

Learners say this course provides engaging and interesting astronomy lessons and covers a variety of topics for beginners. However, some caution that it can require a lot of time and feel lonely without peer support or opportunities for discussion.

Course covers much more than exoplanetary astronomy; good intro to topics like physics and relativity.

"This course gives a much broader overview than it seems, it's an introduction into physics in general, into our Solar system, and into topics like relativity or quantum mechanics."

Course lacks peer support or opportunities for discussion.

"This course is an on-demand one. Peer-reviewed assignments would function better if it were a live course, this way this nice course seems a bit lonely."

Course requires a good amount of time to complete.

"The length is one inhibiting factor for those interested to learn about exoplanets."

Activities

Be better prepared before your course. Deepen your understanding during and after it. Supplement your coursework and achieve mastery of the topics covered in Imagining Other Earths with these activities:

Review Basic Physics

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Refreshes your knowledge of fundamental physics, which will serve as a strong foundation for the course.

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Go over your high school physics notes or textbooks.
Take practice quizzes or mock tests to assess your understanding.

Read 'Astrophysics for People in a Hurry'

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Reinforces key astronomy and astrophysics concepts discussed in the course.

View Merlin's Tour of the Universe, Revised and... on Amazon

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Read through the book at a relaxed pace.
Take notes and highlight important sections.
Discuss the book's concepts with classmates or a tutor.

Form a Study Group with Classmates

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Improves comprehension and retention through collaborative learning and discussion.

Browse courses on Astronomy

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Find a group of classmates with diverse backgrounds and interests.
Establish regular meeting times and a study schedule.
Take turns presenting concepts, leading discussions, and solving problems together.

Six other activities

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Follow Online Tutorials on Planetary Science

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Expands your knowledge of planetary science, complementing the course material.

Browse courses on Planetary Science

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Search for reputable online sources or platforms offering planetary science tutorials.
Select tutorials that align with your areas of interest or the course topics.
Follow the tutorials, take notes, and participate in any interactive exercises.

Practice Kepler's Laws and Planetary Motion Calculations

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Strengthens your understanding of Kepler's Laws and improves your ability to apply them in real-world scenarios.

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Find online resources or textbooks with practice problems.
Solve the problems, checking your answers against provided solutions.
Review the concepts behind the equations you are using.

Tutor Classmates or Participate in Online Forums

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Reinforces your understanding of the course material while helping others learn.

Browse courses on Astronomy

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Review the course material and identify areas where you excel.
Offer tutoring sessions to classmates who may be struggling.
Participate in online discussion forums and provide insightful answers to questions.

Write an Essay Comparing Two Exoplanetary Systems

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Enhances your critical thinking and analytical skills while deepening your understanding of exoplanetary systems.

Browse courses on Exoplanets

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Research and select two exoplanetary systems with contrasting characteristics.
Analyze the properties of each system, including their stars, planets, and orbital parameters.
Write an essay comparing and contrasting the two systems, discussing their similarities and differences.
Proofread and edit your essay.

Create a Database of Interesting Exoplanets

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Provides hands-on experience in gathering and organizing information, deepening your understanding of exoplanets.

Browse courses on Exoplanets

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Research and identify reputable sources for exoplanet data.
Design a database structure to store information such as planet name, host star, orbital parameters, and physical characteristics.
Extract and enter data from the sources into the database.
Create visualizations or reports to present the data in a meaningful way.

Contribute to an Open-Source Planetary Science Project

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Provides practical experience in planetary science research and contributes to the broader scientific community.

Browse courses on Planetary Science

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Identify open-source projects related to planetary science, such as data analysis, modeling, or visualization.
Review the project documentation and familiarize yourself with the codebase.
Find a specific area where you can contribute, such as bug fixes, feature enhancements, or documentation improvements.
Submit your contributions to the project repository and engage with the community.

Career center

Learners who complete Imagining Other Earths will develop knowledge and skills that may be useful to these careers:

Planetary Scientist

Planetary scientists study the physical and chemical properties of planets, moons, and other objects in our solar system. The Imagining Other Earths course would be very useful to someone who wants to enter the field of planetary science as it explores topics such as the formation of planets, the search for extraterrestrial life, and the properties of potentially habitable planets. The course's discussion of the challenges of imaging planets around bright stars is also relevant.

See salaries and explore the career path for Planetary Scientist

Astrobiologist

Astrobiologists research the origin, evolution, and distribution of life in the universe. If you wish to become an astrobiologist, taking this course may be very useful as it delves into topics such as the origin of life on Earth, the search for extraterrestrial life, and the properties of habitable planets.

See salaries and explore the career path for Astrobiologist

Research Scientist

Research scientists conduct scientific research and development. If you want to become a research scientist specializing in astronomy or planetary science, taking this course can serve as a good starting point as it explores topics such as the properties of stars and planets, the search for extrasolar planets, and the challenges of imaging planets around bright stars. This course can help you develop the skills and knowledge needed to conduct research in these fields.

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Geologist

Geologists study the composition, structure, and history of the Earth. This course could be very useful for someone who wants to enter the field, as it delves into topics such as the formation of the Earth, plate tectonics, and the search for extraterrestrial life. The course's discussion of the formation of the Earth and the Moon is particularly relevant.

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Science Communicator

Science communicators translate complex scientific concepts into accessible language for the public. If you are interested in becoming a science communicator specializing in astronomy or planetary science, this course may be useful as it can help build a foundation in these fields. The course explores topics such as the properties of stars and planets, the search for extrasolar planets, the challenges of imaging planets around bright stars, and science communication.

See salaries and explore the career path for Science Communicator

Science Teacher

Science teachers educate students in science subjects. If you intend to teach astronomy or planetary science, taking this course may be useful in building a foundation in these subjects. The course explores topics such as the universe's size, the properties of planets, and the search for extrasolar planets. The course could be useful for developing lesson plans for science classes.

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Science Writer

Science writers communicate complex scientific concepts to the public. If you wish to become a science writer specializing in astronomy or planetary science, this course may be useful as it can help build a foundation in these fields. The course explores topics like the possibility of other Earths, the properties of stars and planets, and the search for extraterrestrial life. The course also delves into science communication.

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Biologist

Biologists study living organisms and their interactions with each other and their environment. If you are interested in becoming a biologist specializing in astrobiology, this course may be useful as it can help build a foundation in this field. The course explores topics such as the origin of life on Earth, the search for extraterrestrial life, and the properties of habitable planets, which are all relevant to astrobiology.

See salaries and explore the career path for Biologist

Data Analyst

Data analysts collect, process, and analyze data. If you wish to become a data analyst specializing in astronomy or planetary science, this course may be useful as it can help build a foundation in these fields. This course explores topics like the properties of stars and planets, the search for extrasolar planets, and the challenges of imaging planets around bright stars which involve analyzing large data sets.

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Astronomer

Astronomers research the physical and chemical properties of celestial objects. If you wish to become an astronomer, taking this course may be helpful in building a foundation in astronomy and planetary science. The course explores topics like the universe's size, the properties of planets, and the search for extrasolar planets, which are all important to astronomical research.

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Paleontologist

Paleontologists study the history of life on Earth. If you want to become a paleontologist, taking this course may be useful in building a foundation in evolutionary biology. The course explores topics such as the evolution of life on Earth, the search for extraterrestrial life, and the properties of habitable planets from an evolutionary perspective.

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Technical Writer

Technical writers create instruction manuals, technical reports, and other documentation. If you want to become a technical writer specializing in astronomy or planetary science, this course may be useful as it can help build a foundation in these fields. The course explores topics such as the properties of stars and planets, the search for extrasolar planets, and the challenges of imaging planets around bright stars. The course is especially helpful for learning science communication techniques.

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Physicist

Physicists research the fundamental laws of nature. If you are interested in becoming a physicist specializing in astrophysics, this course may be useful as it can help build a foundation in this field. The course explores topics such as the universe's size, the properties of stars and planets, and the search for extrasolar planets from a physics perspective.

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Astrophysicist

Astrophysicists research the universe, specializing in stars, the big bang, dark energy, and the laws of physics that govern the universe. If you are interested in becoming an astrophysicist, this course may be useful as it can help build a foundation in astronomy and planetary science. The course explores the possibility of other Earths, examining the properties of stars and planets in our solar system and beyond.

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Software Engineer

Software engineers design, develop, and maintain software systems. If you wish to become a software engineer specializing in astronomy or planetary science, taking this course may be useful as it can help you build a foundation in these fields. The course explores topics like the properties of stars and planets, the search for extrasolar planets, and the challenges of imaging planets around bright stars, which involves developing software to process and analyze large data sets.

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