Louis Pasteur once quoted, “Science knows no country because knowledge belongs to humanity and is the torch that illuminates the world.” In 2020, humankind faced several challenges, but they didn’t stop us from exploring the universe. As the year comes to an end, I have compiled a list of ten of the most thrilling discoveries in space and physics that changed our understanding of the cosmos. I have also provided research papers for your further reference. If you want to know about all the major discoveries in 2020 month-wise, watch this video.

A New Type of Black Hole

Astronomers detected what they believe to be the most powerful and the most massive merger of two black holes in the universe’s history, releasing eight suns’ energy. This was an important observation because it led to forming a new type of black hole – an intermediate black hole, the first to be discovered so far. If we classify the black holes according to their mass, theoretically, they fall into four categories:

Micro Black Holes: Also known as quantum mechanical black holes, the micro black holes are hypothetical. These micro black holes have a certain mass limit. According to the concept of Schwarzchild radius and Compton wavelength, the minimum mass of a micro black hole is 22 micro-grams, also known as the Planck mass.

Stellar Mass Black Holes: The second in the classification of black holes is a stellar-mass black hole. These are some of the most studied black holes, and unlike the micro ones, they do exist in nature. Their formation mechanism is also known to scientists. As the name suggests, a stellar-mass black hole forms when a massive star collapses.

Supermassive Black Holes: the supermassive black holes are the largest black holes found at the centers of the galaxies. They can be a billion times as massive as the Sun.

Intermediate Black Holes: They lie in between the stellar and supermassive black holes. Neither too small nor too big.

2020 discoveries
LIGO/Caltech/MIT/R. Hurt (IPAC)

According to astronomers, two black holes with masses about 85 and 66 times the sun’s mass collided to produce a signal in the most massive merger ever detected. The signal, called GW190521, appears to represent the exact moment the two black holes crashed into each other. The event GW190521 has puzzled astrophysicists. They believe that the black holes that merged into each other are unique in their sizes. Black holes of 85 and 66 solar masses cannot form because of a collapsing star. Scientists believe that these two black holes are themselves a result of mergers.

The Decay of the Higgs Boson

The discovery of the so-called ‘God Particle’ on July 4, 2012, was one of the most exciting discoveries of this decade. The Higgs Boson was the last missing piece of the standard model – a theory that contains the elementary particles that make up our universe. According to the Higgs mechanism, the universe is filled with a field called the Higgs field. A particle’s mass is determined by its interaction with the Higgs field. The more it interacts, the heavier it is.

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Here’s a simple daily life analogy. Suppose you are walking on a road. You can walk easily; there’s no drag because of the atmosphere. But, that’s not the case when you try to walk in a pool of water. Your legs “interact” with water, making it difficult for you to walk in the pool. Similarly, particles interact/couple with the Higgs field, which is omnipresent, and this interaction gives them their elementary mass.

One way to prove a coupling between Higgs and other particles is to look at its decay products. Every time physicists spot a new Higgs-decay particle, that proves a “coupling” between the Higgs and the particles that come out of its decay. This year, particle physicists at the LHC found evidence of the Higgs boson decaying into two muons. Though there’s still more research that needs to be done, scientists are almost certain that the muons they detected came from the Higgs particle’s decay. It has proved muon-Higgs coupling for the first time, demonstrating that an elementary particle gets its mass from the Higgs field.

10 Thrilling Discoveries in 2020 That Changed Our Understanding of the Universe. 1
A summary of the CMS measurements of the Higgs boson couplings to the other fundamental particles, with the predictions by the standard model indicated by the dashed black line. In the lower panel, the ratio between the measured coupling and the standard model prediction is shown. This new CMS result presents the first measurement of the Higgs boson coupling to the muon, indicated by the left-most data point. (Image Courtesy: CERN)

The Birth of a Magnetar

Scientists witnessed the birth of the first magnetar in the universe. Two neutron stars collided in space and gave birth to an exotic object – a magnetar, instead of a black hole.

Magnetars are neutron stars with incredible magnetic fields. The magnetic field of a magnetar can be of the order of 100 trillion T. Such objects are unlikely to support the life of the planets around them. With such a high magnetic field, if a magnetar enters halfway between the Earth and the Moon, it can destroy all the information from the Earth’s credit cards.

When the two neutron stars slammed into each other, they lit up their part of the sky. The spectrum of this event (kilonova) puzzled the scientists. It was at least 10 times brighter than any of the kilonova scientists had seen before. It also contained radio signals. Scientists concluded that the result of this aftermath is a magnetar.

Read all the articles of our Basics of Astrophysics series here

The First Extra-galactic Planet

In 1992, the discovery of the first planet orbiting a star other than the Sun was a great milestone in astronomy. Since then, planetary scientists have found thousands of exoplanets having different sizes, temperatures, and other physical properties. Some of them lie in the habitable zone their parent star and may harbor life.

All the exoplanets discovered so far were a part of our galaxy — the Milky Way. This year, for the first time, astronomers discovered an exoplanet in another galaxy that is 23 million light-years away (one light-year equals about six trillion miles). Also known as the Whirlpool galaxy, it is a part of a binary system of galaxies interacting with each.

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Image of the Whirlpool Galaxy from Chandra. The M51-ULS-1 star system, seen in bright X-rays, is the orange dot in the center of the square. Image via R. Di Stefano et al./ MNRAS.

The planet, labeled M51-ULS-1b, is estimated to be slightly smaller than Saturn. It orbits its stars about 10 times the distance from Earth to the Sun. It was first detected on September 20, 2012, by NASA’s Chandra X-ray Observatory, but went unnoticed in the datasets at the time. Di Stefano and other colleagues only later found it.

A New Particle

In July 2020, particle physicists working on the LHCb experiment found evidence of the first tetraquark comprising all charm quarks and antiquarks. The particle appears to be the first known tetraquark to be made entirely of “heavy quarks,” which are the charm and beauty quarks (but not the top quark, which is the heaviest quark but does not form hadrons).

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Illustration of a tetraquark (Image Courtesy: CERN)

The new tetraquark is dubbed X(6900), with the number referring to its mass of 6900 MeV/c(6.9 GeV/c2). The X denotes that LHCb physicists are not yet certain about the particle’s key properties, including its spin, parity, and quark content.

Water on the Moon

October 2020’s most exciting science news was the discovery of water on the surface of the Moon. The discovery was made using the SOFIA (Stratospheric Observatory for Infrared Astronomy) observatory, the world’s largest flying observatory. It has detected water molecules in the Clavius Crater, one of the largest lunar craters visible from the Earth. Data from this location reveal water in concentrations of 100 to 412 parts per million – roughly equivalent to a 12-ounce bottle of water – trapped in a cubic meter of soil spread across the lunar surface.

This discovery was possible because of the research done by the Cassini-Huygens mission, the Deep Impact Comet mission, ISRO’s Chandrayaan-1 mission, and its ground-based Infrared Telescope facility. However, all these missions could not definitively distinguish the form in which hydration was present – either H2O or OH.

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Researchers scanned the lunar surface at a more precise wavelength than had been used before – six microns instead of three. This allowed them to “unambiguously” distinguish the spectral fingerprint of molecular water, said co-author Casey Honniball of the Hawaii Institute of Geophysics and Planetology. The research paper has been published in the journal Nature Astronomy.

Odd Radio Circles

No research paper yet

Scientists found ghostly circles in the sky that can’t be explained. Radio telescopes in Australia made this strange observation in their sky survey. When astronomers discovered the first circle in the survey, they labeled it as WTF? They first thought it’s an error in the software or the telescope, but they were wrong. But they spotted more such circles using other radio telescopes.

10 Thrilling Discoveries in 2020 That Changed Our Understanding of the Universe. 4

There’s another peculiar thing about these circles. When optical telescopes were pointed at them, there was nothing there. Scientists have dubbed them ORCs, which stands for “odd radio circles.”

Could they be supernovas? These are the clouds of debris left behind when a star in our galaxy explodes. ORCs can’t be supernova remnants because they are too far from the stars in the Milky Way. Are they the Einstein rings? They form when radio waves from a distant galaxy are bent into circles due to gravity. They can’t be Einstein rings because they are too symmetrical for that.

Astronomers have concluded that they aren’t like anything they have seen before. So they must consider things that might exist in space but haven’t been observed to date. Some scientists have even suggested ORCs might be the “throats” of wormholes in spacetime. It is now suspected that there are nearly a thousand such strange objects in the sky. Telescopes around the world are now in search of these newly discovered celestial bodies. But, it’s a tricky job because ORCS are very faint and difficult to find. Astronomers are excited because they seldom stumble upon a new type of object in space.

Detailed video below:

Fast Radio Bursts

Fast Radio Bursts (FRBs) are extremely powerful bursts of radio waves. They are millisecond flashes of highly energetic radio pulses that release more energy than the Sun would in weeks. Discovered back in 2007, they had an extragalactic origin till April 2020, when a dead star SGR 1935+2154 (a magnetar) flared up and became the first source of FRBs in the Milky Way. The source of the first galactic FRB was confirmed in October 2020. This discovery will help astrophysicists understand the phenomenon responsible for these mighty bursts of electromagnetic radiation.

Detailed video below:

Signs of Life on Venus

In September, an international team of astronomers made headlines when it reported finding phosphine — a potential marker of life — in the planet’s atmosphere. The fact that life could exist on a hellish planet where it rains sulphuric acid was difficult to digest. A few weeks later, another team of scientists, after carrying out an independent analysis, challenged the claim. The team that broke the story later confessed that there was an error in their research and that the signals aren’t as strong as they thought were.

The reanalysis, based on radio-telescope observations at the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, concludes that average phosphine levels across Venus are about one part per billion — approximately one-seventh of the earlier estimate.

Where the phosphine comes from remains a mystery. Even at the one-part-per-billion level, there’s too much of it to be explained by volcanic eruptions at the planet’s surface or by lightning strikes in the atmosphere, several scientists said

Increased Density of Space

NASA’s Voyager 2 reported a significant increase in the density of space outside the solar system. Interestingly, the farther the craft went into outer space, the density kept rising, thereby challenging our common notion that space is a vacuum. 

While the density reported from interstellar space is comparatively very low, it is higher than the previously thought values. While inside the solar system, the solar wind has an average proton and electron density of 3 to 10 particles per cubic centimeter. The density of the wind keeps getting fainter as one goes away from the Sun.

Voyager 1 detected a plasma density of 0.055 electrons per cubic centimeters after crossing the heliopause in 2012. On the other hand, Voyager 2 found a plasma density of 0.039 electrons per cubic centimeter when it measured the same in 2019.

Several theories have been put forth time and again to explain this density increase. One theoretical model suggests that the increase might be due to interstellar magnetic fields becoming stronger as they bend over heliopause. Another model predicts that the interstellar wind slows down as they approach heliopause, which builds up the density. However, more data is needed to untangle the mystery of increased density.

Detailed video below:

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