Edwin Hubble Annotated Virgo and Ursa Major Cluster Spectra.

[HUBBLE, Edwin].

$28,500.00

Item Number: 126281

Two rare silver gelatin galaxy spectra annotated by influential American astronomer Edwin Hubble, offering proof of Hubble’s law and direct observational evidence of the validity of the Big Bang theory. Mounted on cardboard, one spectrum reveals the recessional velocity of the Virgo Cluster with Hubble’s pencil annotations on the verso, “NGC 4473 Virgo Cluster Velocity = 2,000 kilometers per second.” The second shows the recessional velocity of Ursa Major with Hubble’s annotations, “Ursa Major Cluster velocity = 15,000 kilometers per second.” In showing that the Ursa Major Galaxy Cluster (located at a distance of about 78 million light years away from earth) was moving at a faster rate than the Virgo Galaxy Cluster (located at a distance of roughly 65 million light years away from earth), Hubble proved that our universe was expanding, and has been doing so since the Big Bang. The prevailing cosmological model explaining the existence of the observable universe from the earliest known periods through its subsequent large-scale evolution, the Big Bang theory developed from observations of the structure of the universe and from theoretical considerations. In 1912, Vesto Slipher measured the first Doppler shift of a “spiral nebula” (spiral nebula is the obsolete term for spiral galaxies), and soon discovered that almost all such nebulae were receding from Earth. In 1924, Hubble’s measurement of the great distance to the nearest spiral nebulae showed that these systems were indeed other galaxies. Starting that same year, Hubble painstakingly developed a series of distance indicators, the forerunner of the cosmic distance ladder, using the 100-inch (2.5 m) Hooker telescope at Mount Wilson Observatory. This allowed him to estimate distances to galaxies whose redshifts had already been measured, mostly by Slipher. In 1929, Hubble discovered a correlation between distance and recessional velocity—now known as Hubble’s law. In fine condition. Exceptionally rare. A desirable piece of astronomical and cosmological history.

American astronomer Edwin Hubble played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and proved that many objects previously thought to be clouds of dust and gas and classified as "nebulae" were actually galaxies beyond the Milky Way. In 1929, he began observing the relationship between the distances to 24 extra-galactic nebulae and their radial velocities as determined from their redshifts and found a roughly linear relationship between the distances of the galaxies and their radial velocities, a discovery that later became known as Hubble's law.