When the Brazos Valley Museum of Natural History kicks off its most recent exhibition, Capturing Time: The Story of Early Photography on Thursday (Jan. 28), a portion of the spotlight will be shining on astronomy connections, past and present.
Texas A&M University astronomer Nicholas B. Suntzeff says the exhibit represents a fascinating collection of cameras and old photographs, including two historic photographic plates he was able to secure on loan from Carnegie Observatories — a partner along with Texas A&M in building the Giant Magellan Telescope. Both were taken by world-renowned astronomer Edwin Hubble in 1923 at Mount Wilson Observatory.
Suntzeff, a university distinguished professor of physics and astronomy, joined the Texas A&M Department of Physics and Astronomy in 2006 as the director of the Texas A&M astronomy program and the inaugural holder of the Mitchell-Heep-Munnerlyn Chair in Observational Astronomy in the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy.
He explains that the plates are labeled to identify the telescope used, specific plate number taken on that particular telescope and the observer of record. In this case, the two plates in the exhibit, H335H and H348H, are the 335th and 348th taken on the Hooker 100-inch telescope (indicated by the first H) by Hubble (indicated by the last H).
Suntzeff says that the H348H plate is especially interesting because it is part of the series that Hubble took late that same year through which he discovered a Cepheid variable in the Andromeda Nebula, now known as the Andromeda Galaxy. He adds that the actual discovery apparently was done using plate H335H by Hubble that was taken two months earlier.
“With this discovery, the scale of the universe was finally understood,” Suntzeff said. “Our Milky Way Galaxy was no longer the large isolated stellar system that astronomers had thought, but one of now hundreds of billions of galaxies.
“Many have seen reproductions of the H335H plate, because in red ink, Hubble has crossed out ‘N’ (for possible nova) and instead wrote ‘VAR!’ as if he was living an ah-ha moment,” Suntzeff said. “But the whole series of plates was used in the discovery, and as such, the plates in the exhibition were part of the discovery of the scale of the universe. Hubble’s famous Cepheid variable star can be clearly seen on the H335H plate.”
Suntzeff notes that the distance to Andromeda also was key in Hubble’s 1929 discovery of a linear expansion of the universe and the first approximate value of the Hubble constant of 550 kilometers per second per megaparsec. That measurement has since been redefined as 74.2 km s-1 Mpc-1 by the SHOES (Supernova Ho for the Equation of State) Team that includes Texas A&M astronomer Lucas Macri.
It was as a postdoctoral research associate at Carnegie Observatories in the 1980s that Suntzeff says he was encouraged by famed 20th century observational astronomer Allan Sandage to focus on Type Ia supernovas — more specifically, their brightness — to measure precise distances.
“Allan Sandage always told us there were only two numbers any astronomer should ever be interested in — the Hubble constant and the deceleration of the universe,” Suntzeff said. “He said a lot of interesting astronomy lies along the path toward those numbers, but the goal is that if you have both, you can understand the evolution of the universe and its probable fate.”
This path led Suntzeff in 1998 to co-discover an unexplained acceleration in the universe’s expansion later honored with the 2011 Nobel Prize in Physics and the first evidence for a mysterious substance known as dark energy that makes up nearly three-quarters of the universe. Coincidentally, Hubble was Sandage’s mentor, adding an extra degree of full-circle intrigue to one particular facet of the trio’s intertwined fate.
In 1917, the eminent theoretical physicist Albert Einstein added a small correction to his General Theory of Relativity of gravity to make the universe unchanging. Between 1929 and 1931, Hubble, using the same Hooker telescope, showed that the universe actually is expanding, causing Einstein to throw out this correction, which he later claimed was the “biggest blunder” of his life. In 2008 as part of the international ESSENCE project, Suntzeff helped show that Einstein’s correction term, called the Cosmological Constant, while small, actually does exist.
Capturing Time: The Story of Early Photography will open tonight at 6 p.m. with a free public lecture by Master Photographer Darrin Hill followed by an opening reception featuring wine, appetizers and gallery viewing. The museum is located at 3232 Briarcrest Drive in Bryan just east of the intersection of Texas State Highway 6 and Briarcrest.
To learn more about the exhibit, which will run through May 30, or the Brazos Valley Museum of Natural History, visit http://www.brazosvalleymuseum.org/.
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