*Thomas Zesiger*Show bio

Thomas has taught electronics and communications engineering, math, and physics and has a master's degree in electrical engineering.

Instructor:
*Thomas Zesiger*
Show bio

Thomas has taught electronics and communications engineering, math, and physics and has a master's degree in electrical engineering.

This lesson talks about what an orbit is and defines some common terms associates with orbit. We also talk specifically about orbits of planets and satellites.
Updated: 02/20/2020

**Orbit** is the path of a body as it moves under the influence of a second body. An example is the path of a planet or comet as it moves around the Sun. Planets and satellites that orbit other bodies trace out a path called an **ellipse**. An ellipse is a closed curve of oval shape wherein the sum of the distances from any point on the curve to two internal focal points is constant. In everyday life you probably just call this an oval. As shown in the picture below, an ellipse has a major axis and a minor axis.

The major axis is always at least as long or longer than the minor axis. When both the major and minor axes are the same length, this is a special case of an ellipse we commonly call a circle. Therefore, orbiting bodies can also trace out a circular path. Although a circle is a special type of ellipse, people commonly refer to satellite and planetary orbits as either circular or elliptical. The **orbital period** is the time to complete one full orbit.

Kepler's laws of planetary motion govern the orbits of planets around the Sun. At first, Kepler expected the planets to move around the Sun in perfect circles, but after years of observation he found that this was not true. **Kepler's first law** of planetary motion states that the path of each planet around the Sun is an ellipse with the Sun at one focus. This is illustrated by the picture in the section above. Kepler also found that the planets do not move around the Sun at a uniform speed, but move faster when they are closer to the Sun and slower when they are farther away. **Kepler's second law** states that the line from the Sun to any planet sweeps out equal areas of space in equal time intervals. This is shown in the picture below.

After ten years of work, Kepler discovered the relationship between the time it takes a planet to orbit the Sun and its distance from the Sun. **Kepler's third law** says that the square of the orbital period of a planet is directly proportional to the cube of the average distance of the planet from the Sun. Mathematically, this is given by the ratio *T*^2/*r*^3 and applies to all planets. The practical application of Kepler's third law is to calculate the radius of a planet's orbit by observation of that planet's orbital period.

A **satellite** is a projectile or smaller celestial body that orbits a larger celestial body. An Earth satellite is a projectile that falls around the Earth rather than into the Earth. Stated another way, a satellite is a fast-moving projectile. The speed of the satellite must be great enough that its falling distance matches the curvature of the Earth. The surface of the Earth drops 5 meters vertically for every 8 kilometers traveled horizontally. Therefore, a projectile must travel at 8 kilometers per second in order to follow the curvature of the Earth and not fall into it.

Unlike planetary orbits, satellite orbits can be circular or elliptical. A satellite traveling at 8 kilometers per second follows the curvature of the Earth and orbits in a circular manner. If it moves any slower, it falls to Earth. If it moves any faster, it traces out an elliptical path.

Kepler's laws apply to satellites as well as planetary motion. Based on the third law, the period of an Earth satellite depends on the distance from the Earth. Periods of typical Earth satellites range from about 90 minutes for satellites close to the Earth, to about 24 hours for communication satellites in geostationary orbits approximately 36,000 kilometers above the Earth's surface. The pictures below compare some typical circular and elliptical orbits of Earth satellites.

An orbit is the path of a body as it moves under the influence of a second body. Planets and satellites move in an elliptical path around the body that they orbit. Planetary motion, as well as satellite motion, is governed by Kepler's laws. Earth satellites move in a circular path when they travel at 8 kilometers per second and follow an oval path if they move faster.

To unlock this lesson you must be a Study.com Member.

Create your account

Are you a student or a teacher?

Already a member? Log In

BackRelated Study Materials

- Biology 202L: Anatomy & Physiology II with Lab
- Biology 201L: Anatomy & Physiology I with Lab
- California Sexual Harassment Refresher Course: Supervisors
- California Sexual Harassment Refresher Course: Employees
- Sociology 110: Cultural Studies & Diversity in the U.S.
- Teaching Financial Literacy & Personal Finance
- Patterns of Human Migration
- Overview of Blood & the Cardiovascular System
- Electrolyte, Water & pH Balance in the Body
- Sexual Reproduction & the Reproductive System
- 2021 Study.com Scholarship for Homeschool Students
- How Teachers Can Improve a Student's Hybrid Learning Experience
- How Long is the School Day in Homeschool Programs?
- Types of Hybrid Learning Models During Covid-19
- Creating Routines & Schedules for Your Child's Pandemic Learning Experience
- How to Make the Hybrid Learning Model Effective for Your Child
- What Are Online Homeschools?

- Imagery in Much Ado About Nothing: Bird & Animal
- Number the Stars Chapter 5 Summary
- Justice in Antigone
- Difference Between Serotype, Genotype, Serovar, Strain & Biotype
- Assessing Compliance in Audit & Non-Audit Engagements
- Calculating Increases in Contributed Net Assets for Not-For-Profit Entities
- Macbeth Act 1, Scene 6: Summary & Quotes
- Quiz & Worksheet - Meaning of A Rose for Emily
- Quiz & Worksheet - Trapezoid Midsegment Theorem
- Equivalent Fractions: Quiz & Worksheet for Kids
- Quiz & Worksheet - Visual Representations of Fractions
- Flashcards - Real Estate Marketing Basics
- Flashcards - Promotional Marketing in Real Estate
- Parts of Speech Worksheets
- Science Lesson Plans

- Supplemental Math: Study Aid
- SAT Physics: Help and Review
- MTTC Economics (007): Practice & Study Guide
- Middle School US History: Tutoring Solution
- Common Core Math - Functions: High School Standards
- CAHSEE - Graphing on the Coordinate Plane: Tutoring Solution
- Overview & Principles of Conversation Management
- Quiz & Worksheet - Activities for Introverts in the Classroom
- Quiz & Worksheet - Nervous System Functions Facts for Kids
- Quiz & Worksheet - The Richter Scale Facts for Kids
- Quiz & Worksheet - Heat Energy Facts for Kids
- Quiz & Worksheet - Professional Development Goals for Teachers

- Constantine the Great Lesson for Kids
- Dorothea Dix in the Civil War: History, Timeline & Facts
- Civil War Activities for Kids
- Sunnyvale, CA Adult Education
- Figurative Language Lesson Plan
- Pre-K Word Walls
- How Many Questions are on the TABE Test?
- New York State (NYS) Common Core Standards
- Civil War Activities for Kids
- Brain Breaks for Kids in the Classroom
- Magna Carta Lesson Plan
- Columbus Day Activities for Kids

- Tech and Engineering - Videos
- Tech and Engineering - Quizzes
- Tech and Engineering - Questions & Answers

- How do you find orbital velocity using two different radii of an ellipse?
- Zero, a hypothetical planet, has a mass of 5.8 x 10^{23} kg, a radius of 3.3 x 10^6 m, and no atmosphere. A 10 kg space probe is to be launched vertically from its surface. a) If the probe is launche
- A geosynchronous satellite orbits at a distance from earth's center of about 6.6 earth radii and takes 24 h to go around once. What distance in meters does the satellite travel in one day? What is its
- A satellite is placed in orbit 7.70 times 10^5 m above the surface of Jupiter. Jupiter has a mass of 1.90 times 10^27 kg and a radius of 7.14 times 10^7 m. Find the orbital speed of the satellite.
- In a classical model of the hydrogen atom, the electron orbits the proton in a circular orbit of radius 0.053nm. What is the orbital frequency? The proton is so much more massive than the electron tha
- Why doesn't the moon fall toward Earth like apples do?
- A satellite has the following position and velocity vectors: R = (5016i + 5520j + 853k) km, V = (0.25i - 0.77j - 6.12k) km/s (a) What is the specific angular momentum of the satellit
- A planet orbits a star in an elliptical orbit. At a particular instant the momentum of the planet is -3.0 x 10^29, -1.5 x 10^29, 0 kg m/s, and the force on the planet by the star is -2.9 x 10^22, -1.3
- At a particular instant, the magnitude of the momentum of a planet is 1.95 x 10^{29} kg.m/s, and the force exerted on it by the star it is orbiting is 8.2 x 10^{22} N. The angle between the planet's m
- A spy satellite is in circular orbit around Earth. It makes one revolution in 7.62 h. (a) How high above Earth's surface is the satellite? (b) What is the satellite's acceleration?

Browse by subject