What is the difference between low Earth orbit, medium Earth orbit, and geostationary orbit?

LEO is up to about 2,000 km above Earth, MEO spans roughly 2,000–30,000 km and includes GPS satellites, and GEO is about 35,786 km high, where satellites can appear fixed over one location.

Why do rockets launch eastward near the equator?

Launching eastward near the equator gains the most boost from Earth’s rotation, reducing the rocket fuel needed to reach orbit.

Why can satellites stay in orbit after their engines turn off?

A satellite’s sideways speed continually carries it around Earth while gravity pulls it inward, creating a continuous free-fall path called an orbit.

Free Course Image Rocket Science for Everyone

Free online course Rocket Science for Everyone

Duration of the online course: 3 hours and 31 minutes

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Build real spaceflight intuition in this free online course—learn orbits, satellites, and rockets, then test your knowledge with quick exercises and a certificate option.

In this free course, learn about

Module 1: Foundations of Orbits and Space
Module 2: Earth Orbits and Orbital Motion
Module 3: Rocket Physics and Propulsion
Module 4: Satellite Systems and Payloads
Module 5: Satellite Launches and Course Conclusion

About the free online course

Rocket science is not just for engineers. It shows up every time you use GPS, watch a live broadcast, check the weather, or capture a photo that depends on space-based technology. This free online course turns the big ideas behind modern spaceflight into concepts you can actually picture, helping you understand what satellites do, how rockets reach orbit, and why the rules of motion in space feel so different from what we experience on Earth.

You will build a clear mental model of orbits by exploring what it really means for something to be in orbit, where space begins, and how different orbital neighborhoods work. Instead of treating acronyms like LEO, MEO, and GEO as trivia, you will connect each region to practical missions—like why GPS satellites sit where they do, how a spacecraft can seem to hover in the sky, and why certain orbits are ideal for mapping every part of Earth in detail. Along the way, Kepler’s and Newton’s laws become tools you can use to reason about speed, altitude, and orbital periods without needing advanced math.

The course then connects those orbital fundamentals to the physics of launch. You will see why airplanes cannot simply fly to space, why rockets behave the way they do, and what tradeoffs separate solid motors, liquid engines, and advanced propulsion approaches. The logic behind multistage rockets and the rocket equation is explained in an intuitive way, so you can understand why reaching orbital speed is such a demanding challenge and how engineers squeeze the most performance out of a launch. You will also learn why Earth’s rotation matters and how launch direction can influence the energy needed to reach orbit.

Finally, you will step inside a satellite and learn how key subsystems work together: structure, power, communication, imaging, and the harsh testing needed to survive launch and space. Short questions and exercises throughout help you check your understanding and turn interesting facts into durable knowledge. Whether you are exploring astronomy as a hobby or looking to strengthen your science foundation, this course offers a practical, confidence-building path into the world above our atmosphere.

Course content

Video class: 1.1 | Why Rocket Science Matters | Rocket Science for Everyone with Yale’s Marla Geha 01m
Exercise: Which everyday activity is used as an example of relying on satellites orbiting about 12,000 miles away?
Video class: 1.2 | What Is an Orbit | Rocket Science for Everyone: How Satellites Orbit with Yale’s Marla Geha 05m
Exercise: What best defines an object being in orbit around Earth?
Video class: 1.3 | Where Does Space Begin? | The Karman Line | Rocket Science for Everyone with Yale’s Marla Geha 05m
Exercise: What altitude is the internationally accepted boundary where space begins (the Kármán line)?
Video class: 1.4 | Earth’s Orbital Regions | LEO, MEO, GEO in Rocket Science for Everyone with Yale’s Marla Geha 03m
Exercise: Which orbital region is defined as 2,000 to 30,000 km above Earth and is where GPS satellites operate?
Video class: 1.5 | Decoding Orbits: Kepler’s Laws 08m
Exercise: According to Kepler's third law, what happens to a satellite's orbital period as its orbital distance (semi-major axis) from Earth increases?

Video class: 2.1 | Low Earth Orbit: LEO Satellites 13m
Exercise: Why does the Hubble Space Telescope orbit higher than the International Space Station?
Video class: 2.2 | Medium Earth Orbit 11m
Exercise: Why are GPS satellites placed in medium Earth orbit (around 20,000 km) rather than low Earth orbit?
Video class: 2.3 | Satellites That Never Move? GEO Orbits | Rocket Science for Everyone with Yale’s Marla Geha 09m
Exercise: What condition must be met for a satellite to appear fixed in one spot in the sky?
Video class: 2.4 | LEO, MEO, GEO: Comparing Earth’s Orbits | Rocket Science for Everyone with Yale’s Marla Geha 12m
Video class: 2.5 | Mapping the Earth: Polar 06m
Exercise: Why are polar orbits especially useful for mapping the entire Earth in detail?
Video class: 2.6 | Orbital Flight: Speed 08m
Video class: 2.7 | Deeper Dive: Kepler’s Law 16m
Exercise: Approximately how high above Earth’s surface must a geosynchronous satellite orbit to have a 24-hour period?

Video class: 3.1 | Newton's Laws: How Rockets Fly 07m
Exercise: Why can a satellite keep moving in orbit even after its engine turns off?
Video class: 3.2 | Why Planes Can’t Reach Space | Rocket Science for Everyone with Yale’s Marla Geha 05m
Exercise: Why can’t a satellite use a jet engine to reach orbit?
Video class: 3.3 | Solid 11m
Exercise: What is a key advantage of liquid rocket engines compared to solid rocket motors?
Video class: 3.4 | The Rocket Equation: Why 95% Fuel Won’t Cut It | Rocket Science with Yale’s Marla Geha 12m
Exercise: According to the rocket equation, which factor most directly limits why a baking soda–vinegar rocket cannot reach orbit?
Video class: 3.5 | Go Further, Faster! Multistage Rockets | Rocket Science for Everyone with Yale's Marla Geha 10m
Exercise: What is the main advantage of using multiple rocket stages during launch?
Video class: 3.6 | Unlock Orbital Speed: Launching Rockets | Rocket Science for Everyone with Marla Geha 07m
Exercise: To maximize the extra delta V gained from Earth’s rotation when launching to orbit, which launch strategy is best?
Video class: 3.7 | Electric, Nuclear 07m
Exercise: Why can electric propulsion (ion rockets) be useful in orbit but not for launching from Earth?

Video class: 4.1 | Understanding Satellite Payloads | Rocket Science for Everyone with Marla Geha 04m
Exercise: Which satellite component is the main structural element that holds the satellite’s “guts and brains” together?
Video class: 4.2 | Powering Satellites: Solar Panels 05m
Exercise: Why do Earth-orbiting satellites typically use both solar panels and rechargeable batteries?
Video class: 4.3 | How Satellites Talk: Radio Waves | Rocket Science for Everyone with Yale’s Marla Geha 08m
Exercise: Why are radio waves commonly used for satellite communication with Earth?
Video class: 4.4 | Hubble to Your Phone: Space Cameras | Rocket Science for Everyone with Yale’s Marla Geha 09m
Exercise: What best explains how a digital camera on a satellite forms an image?
Video class: 4.5 | Satellite Survival: Launch 07m
Exercise: What is the main purpose of a thermal vacuum chamber test for a satellite?

Video class: 5.1 | Satellite Launches: Sputnik, SWOT 09m
Video class: 5.2 | Over and Out: Meet the Team | Rocket Science for Everyone with Yale’s Marla Geha 01m
Exercise: Which contribution is credited with creating the animated visualizations used throughout the class?

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