Edwin Hubble: Discoveries, Theory & Accomplishments

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Electron Orbital: Definition, Shells & Shapes

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:02 Discoveries
  • 1:03 Theory
  • 2:51 Accomplishments
  • 3:13 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed
Lesson Transcript
Instructor: Jeff Fennell

Jeff has a master's in engineering and has taught Earth science both domestically and internationally.

Edwin Powell Hubble was an American astronomer and pioneer of observational cosmology. His observations and discoveries led to a change in the understanding of the universe. This lesson looks at his accomplishments.


In the early 20th century, it was believed by most that the Milky Way was in fact the entire universe. In 1924, Hubble used the reflecting telescope at the Mount Wilson Observatory and began observing nebulae. His observations and calculations led to the realization that these nebulae were, in fact, hundreds of thousands of light-years away from the Milky Way and far larger than the diameter of the Milky Way.

These observations led Hubble to speculate that these nebulae must be located outside the Milky Way and that the universe must be larger than just the Milky Way. In 1924, the American Astronomical Society announced the discovery at an academic conference where it was widely accepted. After continued observations, Hubble began classifying galaxies into categories by their appearance, which would become known as the Hubble classification.


By 1929, Hubble had measured the distance to over 20 galaxies using spectral analysis on the distant objects. Hubble noticed that the spectral lines were red-shifted, meaning they were moving further away. In fact, Hubble noticed the farther the galaxy was, the greater the red-shift was, meaning that the farther away a galaxy was, the faster away it was moving.

Continuing his observations, Hubble noticed the velocity at which galaxies were moving away from us divided by the galaxy distance was a constant, meaning there is a linear relationship between the two. The velocity of galaxies divided by the distance of galaxies is known as the Hubble constant. Hubble formulated his observations into an equation that would become known as Hubble's law, which is:

V = Hsub0 D


  • H is Hubble's constant
  • V is velocity that objects are moving away in km/s (kilometers per second)
  • D is the distance from the observer (usually Earth) to the object being observed

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account