A Field Guide to the Planets

Overview

Take a trip, that’s (okay, okay, we’ll say it) out of this world, with our helpful field guide to our solar system’s iconic planets.

Humanity’s first steps on the Moon were an immense accomplishment in 1969 and a fantastic milestone in the history of space exploration. And yet, how little we knew about our solar system as compared to what we know now! Since those famous steps were taken, we’ve discovered over 150 additional moons of all shapes, sizes, and compositions. We’ve sent spaceships and robotic laboratories to photograph and study each of the planets, dozens of moons, and even the Sun. We’ve discovered ring systems around three additional planets; landed robotic explorers on Mars, asteroids, and comets; and found thousands of exoplanets. What an exciting time this is to explore our solar system and beyond with A Field Guide to the Planets.

Your instructor, Sabine Stanley, Ph.D., a Bloomberg Distinguished Professor at Johns Hopkins University, guides you on a thrilling ride of discovery, illustrated by the phenomenal images NASA has gathered through its telescopes, cameras, and laboratories on Earth; in low-Earth orbit; and throughout the solar system. The solar system that began its formation 4.5 billion years ago is still a work in progress today, a three-dimensional, dynamic, ever-changing system of energy and matter all gravitationally bound to our star. With A Field Guide to the Planets, you will experience the journey of a lifetime—to the edges of our solar system and beyond. You will look to humanity’s next space missions with new excitement, and to our own Earth with greater understanding and appreciation than ever before.

Course Content

01: How the Solar System Family Is Organized

Since 1962, robots have been exploring our solar system to help answer this most important question: Who are we? With fascinating data and images now in hand, explore this family album overview of our planets, dwarf planets, moons, asteroids, Kuiper Belt objects, and long-period comets—and fly through some of our solar system’s most unique features!
Duration: 31 min

02: Mercury, the Extreme Little Planet

Mercury is a planet of many solar system extremes—smallest planet, closest to the Sun, shortest year, most elliptical orbit, smallest axis tilt, and largest fraction of iron. Learn how these characteristics and others have resulted in a planet where the Sun sometimes moves backwards across the sky, where water ice has been found at the poles, and a magnetic field that offers more protection than Mars’.
Duration: 31 min

03: Venus, the Veiled Greenhouse Planet

While the Venusian carbon dioxide atmosphere has resulted in a runaway greenhouse effect and the hottest surface temperature in the solar system, the Earth and Venus actually contain about the same amount of carbon. Explore the forces that resulted in the extreme atmospheric differences between these two otherwise-similar planets.
Duration: 32 min

04: Earth: How Plate Tectonics Sets Up Life

Given the striking similarities between the four terrestrial planets, why is Earth the only one teeming with life? Proposed as a bold theory less than 70 years ago, could plate tectonics be a main driver of life on Earth? Explore the fascinating movement of our planet’s surface and the many ways in which a geologically-active Earth has sustained our biologically-active planet.
Duration: 31 min

05: Orbiting Earth: Up through the Atmosphere

Compared to Venus or the giant planets, Earth has a relatively thin atmosphere. And yet, without this single, fragile layer, life would not have evolved and thrived. Discover the unique properties of each atmospheric layer—and encounter specific ways we’ve explored each layer as a springboard to exploring the rest of our solar system.
Duration: 31 min

06: Exploring the Earth-Moon System

Our Moon, formed from the Earth about 4.5 billion years ago, is by far the largest moon in the solar system relative to its planet’s size. Explore the many ways in which this uniquely coupled system affects the tides on Earth and on the Moon, our rotation and revolution, the process of tidal locking, and even the planetary stability that has allowed for the development of life on Earth.
Duration: 30 min

07: Humans on the Moon: A Never-Ending Story

Even before the invention of telescopes, humans were familiar with the dark lunar highlands and bright maria on the Moon’s surface. But now, with knowledge gained from both robotic and crewed missions, you can also explore fascinating and complex lunar swirls, sinuous rilles, and the lava tubes that hold promise as ideal locations for future lunar bases.
Duration: 32 min

08: Exploring Mars from Space and the Ground

Humanity’s fascination with Mars is never-ending—from the days when we posited a planet covered in straight-line canals and vegetation to NASA’s current Moon to Mars program. Learn how the intriguing similarities and differences between Earth and Mars have resulted in Mars’ planet-wide dust storms, migrating polar ice caps, and 3.9-billion-year-old impact craters.
Duration: 32 min

09: Water on Mars and Prospects for Life

Recent robotic exploration provides tantalizing evidence: Mars’ barren landscape could have been much more Earth-like in the past. With warmer temperatures, a thicker atmosphere, and the possibility of water oceans and tsunamis, could Mars have an Earth sibling that supported life? Learn about the thrilling recent discoveries that will guide future exploration and scientific inquiry on the red planet.
Duration: 32 min

10: Near-Earth Asteroids and the Asteroid Belt

Fans of science fiction, or the natural history of our planet, know that a collision with an asteroid has the potential to obliterate civilization as we know it. With 20,000 asteroids identified in near-Earth orbit, how can collision be avoided? Learn why these rocky bodies, and those in the Asteroid Belt between Mars and Jupiter, never accreted into planets and how we might harness their resources for future space travel.
Duration: 33 min

11: Mighty Jupiter, The Ruling Gas Giant

Does Jupiter have a greater similarity to the Earth or to the Sun? It depends on which characteristics you consider. Explore the many ways in which Jupiter is unique among the planets and consider what our solar system would be like without it. This gas giant might seem too far away to make a difference in your daily life, but without Jupiter, life on Earth might never have had a chance.
Duration: 31 min

12: Jupiter’s Planetlike System of Moons

Today we know of 79 Jovian moons—the spherical Io, Europa, Ganymede, and Callisto, and dozens of other smaller, odd-shaped satellites. Learn why Jupiter’s gravitational forces plus the orbital resonance of the three interior moons make these some of the most promising places to search for extraterrestrial life—and why scientists believe the Jovian system once included generations of other moons, now gone.
Duration: 32 min

13: Saturn and the Rings: Gravity’s Masterpiece

With its exquisitely complex ring system, NASA describes Saturn as the “jewel of our solar system.” Learn what decades of exploration have revealed about the origin and morphology of these ever-changing icy rings and how they interact with Saturn’s closest moons. From the rings to propeller moonlets, a massive hexagonal polar storm, and the giant vortex, our fascination with Saturn never ends!
Duration: 32 min

14: Saturn’s Moons: Titan to Enceladus

With a system of 62 moons located in and far beyond its ring system, Saturn has outer moons that are some of the most fascinating worlds in the solar system. Learn why Titan and Enceladus hold such promise in our search for extraterrestrial life—from global subsurface oceans of water on both moons, to Titan’s Earth-like surface and organic molecules in its atmosphere. It’s no wonder that NASA has announced its Dragonfly mission to Titan, scheduled to launch in 2026.
Duration: 32 min

15: Uranus: A Water World on Its Side

What a fascinating world Voyager 2 revealed in 1986 during its short flyby of Uranus! Learn why Uranus seems to orbit “on its side” surrounded by a delicate system of 13 rings and 27 moons, how we discovered its multi-polar magnetic field, and why scientists think Uranus might contain an ocean made of liquid diamond, with floating chunks of solid “diamond-bergs!”
Duration: 32 min

16: Neptune: Windy with the Wildest Moon

Neptune is the coldest, but also the stormiest, planet in the solar system and the only planet that cannot be seen with the naked eye from Earth. Its moon Triton is the only spherical moon in the solar system that’s an irregular satellite that orbits opposite the direction of all the planets. Learn how tidal forces are not only changing that orbit, but also causing geologic activity on its surface—a surface that contains organic compounds.
Duration: 32 min

17: Pluto and Charon: The Binary Worlds

Although Pluto is no longer categorized as a planet, Pluto the “dwarf planet” and its “moon” Charon are considered the closest thing in the solar system to a binary planet system. Explore the fascinating revelations from the New Horizons mission, including Pluto’s glacial flows, floating mountains, extreme seasons, unexpectedly complex atmosphere, and a surface that appears to be dusted in complex organic molecules.
Duration: 31 min

18: Comets, the Kuiper Belt, and the Oort Cloud

Learn why scientists believe comets—the “leftovers” of planet formation in the outer solar system—could be partially responsible for the flourishing of life on Earth, bringing both water and organic material to the inner solar system. And explore the more distant Oort Cloud, where billions of cometary objects orbit at the outermost boundary of the solar system.
Duration: 32 min

19: How Our Sun Defines Our Solar System

Fly through the corona of what is by far the largest, most massive, and most significant object in the solar system: the Sun. In fact, at 99.9 percent of the total mass of the system, you could say the Sun IS the solar system. With its gravity, heat, light, magnetic fields, and plasma storms, learn how the Sun affects every object in the system—and how we are in a race to learn more about coronal mass ejections before one destroys trillions of dollars’ worth of electronics on Earth.
Duration: 32 min

20: A Solar System Time Machine and Meteorites

Today we see an orderly solar system with planets staying in their orbits around the sun, moons staying in their orbits around the planets, and comets coming and going in predictable fashion. But how did it all start? Learn how a molecular cloud gave rise to a proto-planetary disk in which our solar system developed step by step across time and space—and is developing still.
Duration: 32 min

21: What the Biggest Exoplanets Reveal

Planets orbiting other stars used to be purely in the realm of science fiction. How did we begin discovering them by the thousands? Learn about the methods scientists have used to discover so many exoplanets so quickly. From “hot Jupiters” to “mini-Neptunes” to planets whose clouds rain molten glass, these discoveries demonstrate that ours is not the only type of planetary system possible!
Duration: 31 min

22: Closing in on Earthlike Exoplanets

Beginning in 2009, the Kepler Space Telescope began staring intensively at a single patch of sky, about one quarter of one percent of the sky. After staring for four years straight, scientists had identified about 1,200 new planets. Sift through the Kepler discoveries for planets with a variety of Earth-like features, including presence in a “habitable” zone, and learn why billions of Earthlike planets are estimated to exist in our galaxy.
Duration: 31 min

23: Planets Migrated in Our Early Solar System!

The surprising detection of gas giant planets orbiting extremely close to other stars has led to the realization that planets can form in one part of a stellar system and then migrate to another part. Did that happen in our own solar system? Learn about the evidence for a “Late Heavy Bombardment” on the Moon, Mars, and Mercury, how migration of one or more giant planets could have caused it, and how such migration could have affected the solar system we see today.
Duration: 31 min

24: Human Futures in the Solar System

What are the next big ideas that will help us ask and answer the next big questions? Consider the fascinating future technologies of centimeter-sized satellites propelled by laser photons, liquid mirror telescopes on the Moon, a magnetic shield large enough to help terraform Mars, and more. Nourish your imagination, and experience the inspiration of space exploration!
Duration: 33 min