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1929 Cosmic Times

This poster is the second edition of the Cosmic Times, with the publication date chosen to coincide with the announcement of Hubble's results which found that the Universe was expanding. These results were contrary to Einstein's assumption of a static Universe. In addition, in order to show that the galaxies were all moving away from us, Hubble first showed that there were other galaxies outside the Milky Way.

• Download 1929 poster, newsletters, and glossary
• Teacher's Guide to the 1929 articles
• 1929 Lessons

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1929 Article Overview

Age of Universe: 2 Billion Years
Size of Universe: 280 Million Light Years

Article	Thread	Summary
Andromeda Nebula Lies Outside Milky Way Galaxy	Size of the Universe	Hubble's observations of Cepheid variable stars in Andromeda show that it is actually separate from our Milky Way galaxy.
"Great Debate" Resolved	Size of the Universe	Hubble's distance to the Andromeda Nebula resolves the debate held in 1920 between Harlow Shapley and Heber Curtis over whether the spiral nebulae were part of our Galaxy or outside it.
Universe is Expanding	Expanding Universe	Hubble's careful distance calculations coupled with redshift measurements show that the Universe is expanding.
Sidebar: The Minds atop Mount Wilson	--	Biographical information about Hubble and his assistant, Humason.
Sidebar: Classifying Nebulae	--	Brief overview of Hubble's system of classifying galaxies.
In Their Own Words	--	Snippets of papers published by other astronomers during this time. The snippet here is from Hubble about observing distant objects in the Universe.

1929 Lesson Overview

Activity	Summary	Grade		Discipline
		MS	HS
Discovering the Milky Way	Students look at historic astronomical data to find the pattern originally seen by Henrietta Leavitt.		x	Physics, Astronomy
Just How Far is that Star?	Students work with light meters to determine how astronomers find distances to objects of known brightness.		x	Physics, Astronomy
Cosmic CSI	Students explore what spectra from different elements looks like and how astronomers can learn composition of objects with this tool.	x		Earth Science, Physical Science, Chemistry
Determining the Universe	Students measure the size of several galaxies to reproduce a plot of Hubble's Law.		x	Physics, Astronomy
Unsung Heroes of Science	Students investigate figures in science who are often overlooked.	x	x	Multidisciplinary