The progress of astronomy leapt forward when astrophysics was added to its sub-disciplines. The science of astrophysics essentially started in the early 19th century and has advanced at a great pace, especially so in the last century.
In fact, we might suggest that the 20th century was an epoch of enlightenment, in which our understanding of the Universe was revolutionized. As with many of today’s sciences, we might wonder whether this rate of progress will continue. Science advances in two ways.
On the one hand, we have a gradual accumulation of knowledge and data. There are many examples of this in astronomy. Just think of the slow and painstaking accumulation of accurate stellar distances, masses, luminosities, temperatures, and spectra. On the other hand, we have “breakthroughs”.
These are major paradigm shifts, the realization that we have actually been ‘barking up the wrong tree.’ Here, our concept of the astronomical Universe changes dramatically over a relatively short period of time.
Earth’s cosmic position is a good example. In the 15th century, the vast majority of thinkers placed the Earth at the center of the Universe. By the 17th century, our understanding of the cosmos had changed dramatically and Earth was demoted to being a mere planet.
The Sun then became the center of the Universe, but even this view did not last long. In this article, we aim to recognize the major astronomical breakthroughs that occurred in the 20th century. These stand out as landmarks in the progress of astronomical history.
Astronomical Discoveries and how they where discoveried
1 Pattern recognition
People have been gazing toward the sky and making observations facts since the most ancient civilizations, and likely before that as well!
The simple power of pattern recognition is considered the separation point between sentient and non-sentient beings.
Maybe if those civilizations hadn’t failed or died out, they might establish an even better understanding of the Universe than we have, but the most important conclusion that each of them agrees on is that stars and planets have fixed paths and predictable trajectories. This is a fundamental concept of astronomy.
2 Earth moves around the Sun
In 1543 AD, when Copernicus became the first to show the math behind such an INSANE though, he was generally criticized for his radical views. Truth be told, the “heliocentric model” was revolutionary to the point that Copernicus was really reluctant to promote it.
However, once the idea was finally accepted, it eliminated many problems with older astronomical studies and is considered the first major realization of our place in the Universe. We understood that the Sun is a star, not a God and that we aren’t situated at the focal point of the universe.
3 Kepler’s Laws
Johannes Kepler demonstrated that the planets moved around the Sun in elliptical circles, as opposed to perfect circles as was believed then. In 1609, this was progressive, since it implied that the separation between the planets and the Sun changed after some time.
Finally, the world understood the reason behind seasons and the apparent motion of planets.
Without these disclosures, cosmologists would have had a considerably more troublesome time endeavoring to clarify why the Sun’s effect on Earth’s changes and why the rates of different planets appear to fluctuate after some time.
4 Jupiter’s Moons
Galileo found four moons of Jupiter in 1610 utilizing a telescope that he designed and made himself. They were the principal moons found that didn’t circle Earth, making them the most imperative bit of proof for Copernicus’ model of heliocentrism.
This was unmistakable confirmation that planets other than Earth had moons and that we weren’t as special as we suspected. The universe, if anything, teaches us humility!
5 Understanding The Milky Way
The Milky Way is not the only galaxy in the Universe. Many of the fuzzy nebular blobs that Charles Messier (1730-1817) charted in the mid-18th century are actually distant star systems just like our own. The breakthrough occurred in 1923 when Edwin Hubble (1889-1953) used the 100 inch Hooker reflector and discovered a Cepheid variable in M31 (later published in Hubble, 1929a).
By 1924 he had discovered twelve more. Using the calibrated Magellanic Cloud Cepheid data obtained by Henrietta Leavitt (1868-1921), see Leavitt & Pickering (1912), he realized that M31 was
900,000 light-years away, nine times further than the outer edge of our Milky Way galaxy.
Soon it was realized that the Universe contained over 1011 galaxies and not just the one.
This is a marvelous example of an astronomical breakthrough and paradigm shift. Astronomers did not just double the number of galaxies, or change it by a factor of ten.
A single unique entity, our Galaxy, suddenly, in the late 1920s found itself to be merely one among over 125 billion.
6 Herschel’s Map
Space expert William Herschel and his sister Caroline deliberately mapped the night sky, cataloging a huge number of stars and nebulae in a very nearly five-decade process.
Distributed in 1834, this guide uncovered the shape and size of the Milky Way, which ended up being plate molded, as opposed to a circle.
It likewise made us feel much progressively insignificant to discover that the Sun was found not even close to the middle. We, at last, started to acknowledge that we were simply glad little individuals in our very own edge of the universe.
He additionally found Uranus and proposed to name it ‘GeorgiumSidus’, which would have been such a better name to Uranus. Truly, people, it’s been more than 150 years… give the jokes a rest.
7 Theory of Relativity
Before Einstein proposed his Theory of Relativity, the cosmology community carefully complied with Newton’s three laws of motion.
Everything changed when Einstein contended that movement was relative and that light could be influenced by gravity. The likelihood that mass could twist space-time and that sufficiently extensive masses could even twist light shook mainstream researchers since the light was viewed to be absolutely consistent.
This hypothesis reformed space science and tackled numerous issues that had been deemed impossible within Newton’s confining laws.
8 Expansion of the universe
At the point when Edwin Hubble told the world that the Universe is growing, it was historic, without a doubt. In the wake of following the development of different systems (which he was likewise the first to find), he reasoned that they are moving far from us, while additionally continually speeding up.
He additionally presumed that a large portion of the nebulae unmistakable in the night sky was really cosmic systems.
This gave additional proof to help the hypothesis of the Big Bang and changed our idea about the origination of the Universe.
9 Cosmic Microwave Background radiation (CMB)
Uniformly defined radiation that fills the Universe was found accidentally by two Bell Telephone technicians in 1964 while working on satellite communications.
Since the light from article one light-year away takes one year to contact us, the CMB works like a snapshot of the universe as it were millions of years in the past.
The ramifications of this disclosure were significant since the consistency of the radiation seems to affirm the thought that the Universe started from a solitary occasion from which everything else streams. This reality underpins the hypothesis of an extending universe, and along these lines, The Big Bang.
10 Extrasolar Planets
An extrasolar planet, otherwise called an exoplanet, is a planet found outside our Solar System. The presence of exoplanets was not too amazing, yet the strategy by which they were found has changed the course of space science.
Almost 3000 exoplanets have been found since 1988. Approximately 1 of every 5 Sun-like stars has an Earth-sized planet inside the habitable zone of the star.
Accepting there are 200 billion stars in the Milky Way, which would mean 11 billion tenable Earth-like-planets in the Milky Way alone.
Most researchers trust that it won’t be long until we discover a planet loaded with additional earthbound life simply waiting to be reached.
Likewise, a large number of these livable planets could harbor human life also, after interstellar travel is developed and perfected.
Bonus astronomical discoveries special mentions
Understanding the composition of the baryonic matter in the Universe.
In1900, the general consensus was that stars were made of “earth”. Since 1925 astronomers started to realize that stars are predominantly made of hydrogen and helium, this clearly is a major paradigm shift.
Cecelia Payne led the way, in her famous Harvard Ph.D. thesis Stellar Atmospheres, A Contribution to the Observational Study of High Temperature in the Reversing Layer of Stars, a thesis that led to her 1925 Radcliffe College (Cambridge, Massachusetts) doctorate.
She used the 1920 equation developed by MeghnadSaha (1894-1956) to convert spectroscopic line strengths into atomic number counts and eventually stellar photospheric compositions.
A second important breakthrough in this field was the realization that stars come in two main compositional sorts; metal-rich Population I and metal-poor Population II.
This was discovered by Walter Baade (1893-1960) in 1943, using photographic plates that he had taken of the M31, The Andromeda Galaxy, with the Hooker, under the conditions of the wartime blackout.
A third breakthrough was the explanation of why the stars actually had the compositions that they did, and how that composition varies with time.
There were two components to this breakthrough: first the explanation of the initial 75%:25% hydrogen-helium mix produced just after the Big Bang, and second the 1957 breakthrough due to the work of Margaret Burbidge, Geoffrey Burbidge, William Fowler, and Fred Hoyle.
This takes the nuclear e-process that converts hydrogen into helium and extends the sequence on to the production of carbon and oxygen, silicon, sulfur, argon and calcium, and ending with the iron peak.
These four scientists then showed how the r-process takes over in supernova explosions and moves the composition on towards gold, platinum, and uranium.
Dark Matter
Most of the Universe seems to consist of material that we cannot see. The “luminous”, radiating, bodies in our Universe only make up about 4% of the total mass.
This strange and still unexplained phenomenon was first discovered by Fritz Zwicky (1937). The application of the virial theorem to the Coma cluster of galaxies indicated that it contained 400 times more mass than that indicated by the visible parts of the galaxies.
Galaxies are more massive than they look.
We can count all the stars and add up their masses, and then include the gas and the dust. But it is still not enough. Vera Rubin showed that the velocity curve of a typical galaxy indicated that the velocity of rotation did not decrease significantly as a function of distance from the galactic spin axis.
Everyone was expecting most of the galactic mass to be in the nucleus. If this were the case, the rotation velocity would decrease as the inverse square root of the distance from the massive central body (as happens in the Solar System).
The typical spiral galaxy actually has a massive halo, which has a density that decreases as a function of the inverse square of the distance from the spin axis.
The composition, or form, of the “missing mass” in this halo is not known. Some of our contributors to the breakthrough listings suggested that the discovery of “dark matter” should only achieve breakthrough status when the actual physical form of the dark matter has been identified.
This is somewhat unfair. One of the great joys of modern astronomy and astrophysics is the host of mysteries that abound.
Space science may remain the most underdeveloped part of science, even after such a significant number of leaps forward throughout the hundreds of years, but in order to better understand ourselves, we need to understand our place amongst the stars.
Related questions
How did life begin?
Four billion years ago, something started stirring in the primordial soup. A few simple chemicals got together and made biology – the first molecules capable of replicating themselves appeared.
We, humans, are linked by evolution to those early biological molecules that got life started on earth.
Are we alone in the universe?
Perhaps not. Astronomers have been scouring the universe for places where water worlds might have given rise to life, from Europa and Mars in our solar system to planets many light-years away.
Radio telescopes have been eavesdropping on the heavens and in 1977 a signal bearing the potential hallmarks of an alien message was heard.
Astronomers are now able to scan the atmospheres of alien worlds for oxygen and water. The next few decades will be an exciting time to be an alien hunter with up to 60bn potentially habitable planets in our Milky Way alone.