Cosmic Distance Ladder – Part 4 of 4

The final part of the Cosmic Distance Ladder series.

How I See It

On March 15,1929, Edwin Hubble presented a paper to the National Academy of Sciences. A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae stated that the 24 objects he studied were receding from Earth in a specific pattern. The farther ones were receding faster. In fact, the distance vs recessional velocity was a linear direct proportion. This finding has had profound consequences on our understanding of the nature of the universe, when it originated, how large it is, and what future course it will take.

This is the final part of the series Cosmic Distance Ladder. Here are links to part 1, part 2, and part 3. As promised, the arguments and information will be presented as conceptually as possible without emphasis on the mathematical details. The goal of this series has been to assist the non-technically trained reader to understand more about how we…

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Cosmic Distance Ladder – Part 3

How I See It

Part 3 of the Cosmic Distance Ladder series is a little longer than the previous two. We will see which tools astronomers use to find the distances to objects much beyond our own home galaxy. There will be some discussion of supernovae and black holes.

The first part of this post advances up the distance ladder by telling the remarkable story of Henrietta Swan Leavitt. Her contributions to the study of Cepheid variable stars led to a method to know intergalactic distances millions of light years from our Milky Way. The previous Cosmic Distance Ladder – Part 2 discussed stellar parallax and main sequence fitting as methods to determine distances to objects within the confines of the Milky Way vicinity. If you wish to see parts 1 & 2, they are linked here and here.

The Harvard Calculators

Henrietta was the daughter of Congregational church minister George Roswell Leavitt and Henrietta Swan…

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Cosmic Distance Ladder – Part 1

How I See It

(Parts part 2, part 3, and part 4.)

Many great articles and news stories are written on the subjects of Astronomy and Cosmology. They reveal the wonders and beauty of the universe stretching out to enormous distances in all directions we look.

Perhaps the most challenging aspect of those stories is the sense of scale being described within them. This blog series is meant for readers who love these offerings, but have little or no formal background study in astronomy. Yet, they want to know more about it.

This Cosmic Distance Ladder series will take you a few rungs at a time over the next posts. This is the first of 4 parts of the series Cosmic Distance Ladder. Here are links to part 2, part 3, and part 4. Each rung of the ladder describes the methods used by astronomers to measure…

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