Maarten Schmidt via Caltech.
Today in science: On February 5, 1963, Dutch astronomer and Caltech professor Maarten Schmidt had a eureka moment while studying a quasi-stellar radio source, or quasar, which profoundly affected how scientists would see the universe. Schmidt studied a quasar known as 3C273 that looked like a star with the addition of a mysterious jet. But even stranger was the spectrum. Astronomers examine the spectrum, or range of wavelengths of light, that a star emits to decipher the object’s composition. But the emission lines of the spectrum of 3C273 did not correspond to known chemical elements. Schmidt suddenly realized that 3C273 contained the very common element hydrogen. It was just difficult to identify because the hydrogen spectral lines did not appear where expected; instead, they had shifted sharply to the red end of the spectrum. Such a large redshift could occur if 3C273 were very distant, about 3 billion light years away.
Dr. Schmidt recalled the excitement of his revelation to EarthSky. He said:
This realization came right away: My wife still remembers walking back and forth most of the evening.
The implications were exactly this: for the quasar to be so distant and still visible, 3C273 must be intrinsically very bright and very powerful. It is now thought to shine with the light of two trillion stars like our sun. That is hundreds of times the light of our entire Milky Way galaxy. Yet 3C273 appears to be less than a light year in diameter, unlike 100,000 light years for our Milky Way.
EarthSky lunar calendars are cool! Stock almost empty. Order now.
The quasar 3C273 is not only far away. It is also extremely luminous, indicating powerful energy-producing processes unknown in 1963. Schmidt announced his disclosure about quasars in the magazine Nature on March 16, 1963.
Maarten Schmidt is a Dutch astronomer who recognized in 1963 that quasars are located in the very distant universe and must therefore be extremely powerful energy sources.
X-ray of 3C273 and its jet. Today, this quasar is known to be in the center of a giant elliptical galaxy. Image via Chandra X-ray Observatory.
Hundreds of thousands of quasars are known today, and many are further away and more powerful than 3C273. It is no exaggeration to say that they have turned the science of astronomy upside down. For example, why are these powerful quasars so far out in space? Light travels at a finite speed (186,000 miles per second), and we only see quasars in deep space and thus in the distant past. These strange objects only existed in the early universe and no longer exist in the current universe. Why?
In the 1960s, 3C273 and other similar quasars were strong evidence against Fred Hoyle’s Steady State theory, which suggested that matter is constantly being created as the universe expands, leading to a universe that is the same everywhere. The quasars showed that the universe is not the same everywhere and thus helped usher in the Big Bang cosmology.
But the Steady State theory was losing ground even before 1963. The biggest change brought about by Maarten Schmidt’s revelation about the quasar 3C273 was the way we think of our universe.
In other words, the idea that 3C273 was extremely luminous and yet took up such a relatively small space suggested powerful energies that astronomers had never thought of before. 3C273 gave astronomers one of their first hints that we live in a universe of colossal explosive events – and extreme temperatures and luminosities – a place where mysterious black holes abound and play a major role.
According to a March 2013 email from Caltech:
In 1963, Schmidt’s discovery gave us an unprecedented look at how the universe behaved at a much younger period in its history, billions of years before the birth of the sun and its planets. Schmidt later discovered, along with his colleague Donald Lynden-Bell, that quasars are galaxies with supermassive black holes billions of light years away, not stars in our own galaxy, as was once believed. His seminal work dramatically scaled the observable universe and furthered our current view of the violent nature of the universe in which massive black holes play a dominant role.
What are quasars? Astronomers today believe that a quasar is a compact area in the center of a galaxy in the early Universe. The compact region is believed to surround a central supermassive black hole, just as the black hole is at the center of our own Milky Way and many (or most) other galaxies. The powerful clarity of a quasar is thought to be the result of processes that take place in one accretion disk, or disk of material around the black hole, as these supermassive black holes devour stars that pass too close. These types of activities take place during galaxy mergers, which peaked in the early universe.
ULAS J1120 + 0641 was the freshest quasar known in 2011. The quasar appears as a faint red dot close to the center. Composite image created from the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey, via Wikimedia Commons.
Chinese-born American astrophysicist Hong-Yee Chiu came up with the name quasar in May 1964 in publication Physics Today. He wrote:
Until now, the awkwardly long name “quasi-stellar radio sources” has been used to describe these objects. Since the nature of these objects is completely unknown, it is difficult to make a short, appropriate nomenclature for them so that their essential properties are clear from their name. For convenience, the abbreviated form ‘quasar’ is used in this article.
Currently the most famous quasar is ULAS J1342 + 0928, but it can be dethroned at any time. It has a redshift of z = 7.54 and existed when the universe was about 690 million years old, only 5% of its current age.
In short, today in science, on February 5, 1963, Maarten Schmidt unraveled the mystery of quasars and pushed the edges of our cosmos. His understanding of the most distant and luminous objects known to us has changed the way scientists view the universe.
Are you enjoying EarthSky so far? Sign up for our free daily newsletter today!
