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1919 Cosmic Times

This poster is the first edition of the Cosmic Times, with the publication date chosen to coincide with the announcement of the first test of Einstein's General Theory of Relativity. Einstein published the theory in 1915, but the first test supporting General Relativity was announced in 1919. In fact, it was this test of General Relativity that really propelled Einstein to "rock star" status.

• Download 1919 poster, newsletters, and glossary
• Teacher's Guide to the 1919 articles
• 1919 Lessons

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1919 Article Overview

Age of Universe: Infinite
Size of Universe: 300,000 Light Years

Article	Thread	Summary
Sun's Gravity Bends Starlight	Expanding Universe	Observations of stars near the Sun during the eclipse of 1919 show that the starlight bends just as predicted by General Relativity.
Sidebar: Why a Total Eclipse?	--	Describes why observers needed a solar eclipse to make observations of starlight bending around the Sun.
Mount Wilson Astronomer Estimates Milky Way Ten Times Bigger Than Thought	Size of the Universe	Astronomer Harlow Shapely finds that the Milky Way is 10 times bigger than previous measurements, using the period-luminosity relationship for Cepheid variables as discovered by Henrietta Leavitt.
Expanding or Contracting?	Expanding Universe	Einstein's theory of General Relativity predicts that the Universe cannot be static – it must be expanding or contracting. Einstein adds the "Cosmological Constant" to keep the Universe static.
In Their Own Words	--	Snippets of papers published by other astronomers during this time. The snippets highlight the Cepheid period-luminosity relationship, redshift of galaxies, and the nature of spiral nebulae.

1919 Lesson Overview

Activity	Summary	Grade		Discipline
		MS	HS
Einstein and His Times	Students look at other 1919 events to decide if Einstein should be elected "Man of the Year"	x	x	Multidisciplinary
Eclipses and Moon Phases	Students explore how eclipses happen and why Einstein needed a total eclipse to image stars near the Sun.	x		Earth Science, Physical Science
Two Versions of Gravity: Newton and Einstein	Students explore the differences between Einstein and Newtonian gravity through an information exchange.		x	Physics, Astronomy
Einstein's Gravity	Students use hands-on demonstration to understand how General Relativity explains gravity and explores Einstein's theories through outside research.		x	Physics, Astronomy