Resume Reading — The Shrinking Earth


The Shrinking Earth

The farther out we peer into the universe, the punier our home planet seems.

Click on each date for more information. Sources:3rd century BCE: Eratosthenes measures diameter of Earth…By Amos Zeeberg

Click on each date for more information.

3rd century BCE: Eratosthenes measures diameter of Earth

2nd century BCE: Hipparchus approximates distance to Moon

A Quick Spin Around the Big Dipper

From our perspective here on Earth, constellations appear to be fixed groups of stars, immobile on the sky. But what if we could change that perspective? In reality, it’d be close to impossible. We would have to travel tens...READ MORE

Measuring the Universe:

1672: Gian Domenico Cassini cracks length scale of solar system out to Saturn

Blind Watchers of the Sky:

1838: Friedrich Bessel makes first measurement to star besides the Sun

Measuring the Universe

1913: Ejnar Hertzsprung measures distance to nearby galaxy

How Old Is the Universe:]
Measurement of Starlight:

1924: Edwin Hubble measures distance to Andromeda, nearest spiral galaxy

Alan Hirshfeld:
How Old Is the Universe

1929: Hubble finds more distant galaxy & evidence for expansion of universe

Alan Hirshfeld
Edwin Hubble: Mariner of the Nebulae:
The Expanding Universe: Astronomy’s “Great Debate,” 1900-1931:>

1952: Walter Baade doubles size of known universe by reinterpreting star distances

Alan Hirshfeld…..61…97H/0000112.000.html….83…10H/0000022.000.html

1965: Radio telescopes pick up distant quasar…141.1295S

2012: Hubble Ultra Deep Field shows galaxies in universe’s infancy

Ethan Siegel:

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