My Science School

Freeman Dyson may be gone, but his famous alien-hunting idea will likely persist far into the future.

Dyson, a quantum physicist who died at age 96 on Feb. 28, recalled in a 2003 interview just how he first advanced his concept of a "Dyson sphere," which could betray the existence of an advanced alien civilization. 

A Dyson sphere is a theoretical mega-engineering project that encircles a star with platforms orbiting in tight formation. It is the ultimate solution for living space and energy production, providing its creators ample surface area for habitation and the ability to capture every bit of solar radiation emanating from their central star

Because of their infrared radiation, Dyson spheres are considered a type of technosignature — a sign of activity that distant astronomers could use to infer the existence of intelligent beings in the universe, according to a NASA report. A handful of Earth-based researchers have scanned infrared maps of the night sky in hopes of spotting Dyson spheres, but so far, nobody has seen anything out of the ordinary.

In 2015, astronomer Tabetha Boyajian, then at Yale University, reported on the mysterious dimming of light from a star called KIC 8462852, whose irregular flickering looked like nothing researchers had ever seen before. Other scholars suggested the weird light dips could result from a partially built Dyson sphere, and the idea caused a media sensation. Campaigns to look for other signs of technological activity from the entity, which came to be known as Tabby's star in honor of Boyajian, have turned up empty, and most researchers now think the object's light patterns have some kind of nonalien explanation.

 

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The Moon has fascinated us for centuries with several countries already having sent their probes and people to explore it But how was Earth's closest companion formed? Well there have been many theories about the formation of the Moon. The one that many scientists agree with the most is the giant-impact hypothesis.

When Earth was hit by Theia

Scientists believe the Moon was formed when a planet about the size of Mars collided with Earth Theia, as dubbed by scientists crashed into Earth when it was still a very young planet This collision sent dunks of Earth's cast into space Gravity then bound these particles together in space forming the Moon.

The Apollo missions conducted by NASA between 1969 and 1972. brought back over a thing of a tonne of rock and soil from the Moon. When this was analysed it was found that the Earth and the Moon hat some chemical and isotopic similarities, suggesting that they have a linked history.

However, this theory has its challenges with many models suggesting 60% of the Moon would have been made up of Theia's rocks if the giant-impact hypothesis is true.

The other theories

Prior to the Apollo missions, there were three theories that were speculated about the formation of the Moon.

Capture theory: This suggests the Moon was a wandering body in space, like an asteroid which formed elsewhere in the solar system and was captured by Earth's gravity when it passed near the planet.

Accretion theory: This theory suggests the Moon was created along with Earth during its formation 

Fission theory: According to this theory, the Earth was spinning so fast that some of its material broke away and began to orbit it after being captured by its gravity.

 

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The theory of a Hot Big Bang is the most widely accepted hypothesis for the origin of the universe, but it still leaves many questions unanswered. 

Since the early part of the 1900s, one explanation of the origin and fate of the universe, the Big Bang theory, has dominated the discussion. Proponents of the Big Bang maintain that, between 13 billion and 15 billion years ago, all the matter and energy in the known cosmos was crammed into a tiny, compact point. In fact, according to this theory, matter and energy back then were the same thing, and it was impossible to distinguish one from the other.

Adherents of the Big Bang believe that this small but incredibly dense point of primitive matter/energy exploded. Within seconds the fireball ejected matter/energy at velocities approaching the speed of light. At some later time—maybe seconds later, maybe years later—energy and matter began to split apart and become separate entities. All of the different elements in the universe today developed from what spewed out of this original explosion.

Big Bang theorists claim that all of the galaxies, stars, and planets still retain the explosive motion of the moment of creation and are moving away from each other at great speed. This supposition came from an unusual finding about our neighboring galaxies. In 1929 astronomer Edwin Hubble, working at the Mount Wilson Observatory in California, announced that all of the galaxies he had observed were receding from us, and from each other, at speeds of up to several thousand miles per second.

 

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A supernova is the biggest explosion that humans have ever seen. Each blast is the extremely bright, super-powerful explosion of a star.

One type of supernova is caused by the “last hurrah” of a dying massive star. This happens when a star at least five times the mass of our sun goes out with a fantastic bang!

Massive stars burn huge amounts of nuclear fuel at their cores, or centers. This produces tons of energy, so the center gets very hot. Heat generates pressure, and the pressure created by a star’s nuclear burning also keeps that star from collapsing.

A star is in balance between two opposite forces. The star’s gravity tries to squeeze the star into the smallest, tightest ball possible. But the nuclear fuel burning in the star’s core creates strong outward pressure. This outward push resists the inward squeeze of gravity.

When a massive star runs out of fuel, it cools off. This causes the pressure to drop. Gravity wins out, and the star suddenly collapses. Imagine something one million times the mass of Earth collapsing in 15 seconds! The collapse happens so quickly that it creates enormous shock waves that cause the outer part of the star to explode!

Usually a very dense core is left behind, along with an expanding cloud of hot gas called a nebula. A supernova of a star more than about 10 times the size of our sun may leave behind the densest objects in the universe—black holes.

Scientists have learned a lot about the universe by studying supernovas. They use the second type of supernova (the kind involving white dwarfs) like a ruler, to measure distances in space.

They have also learned that stars are the universe’s factories. Stars generate the chemical elements needed to make everything in our universe. At their cores, stars convert simple elements like hydrogen into heavier elements. These heavier elements, such as carbon and nitrogen, are the elements needed for life.

Only massive stars can make heavy elements like gold, silver, and uranium. When explosive supernovas happen, stars distribute both stored-up and newly-created elements throughout space.

 

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At the very heart of the Milky Way is a region known as Sagittarius A. This region is known the home of a supermassive black hole with millions of times the mass of our own Sun. And with the discovery of this object, astronomers have turned up evidence that there are supermassive black holes at the centers most spiral and elliptical galaxies.

The best observations of Sagittarius A*, using Very Long Baseline Interferometry radio astronomy have determined that it’s approximately 44 million km across (that’s just the distance of Mercury to the Sun). Astronomers have estimated that it contains 4.31 million solar masses.

The discovery of a supermassive black hole at the heart of the Milky Way helped astronomers puzzle out a different mystery: quasars. These are objects that shine with the brightness of millions of stars. We now know that quasars come from the radiation generated by the disks of material surrounding actively feeding supermassive black holes. Our own black hole is quiet today, but it could have been active in the past, and might be active again in the future.

Some astronomers have suggested other objects that could have the same density and gravity to explain Sagittarius A, but anything would quickly collapse down into a supermassive black hole within the lifetime of the Milky Way.

 

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According to research, the universe is approximately 13.8 billion years old. How did scientists determine how many candles to put on the universe's birthday cake? They can determine the age of the universe using two different methods: by studying the oldest objects within the universe and measuring how fast it is expanding. 

The universe cannot be younger than the objects contained inside of it. By determining the ages of the oldest stars, scientists are able to put a limit on the age. The life cycle of a star is based on its mass. More massive stars burn faster than their lower-mass siblings. A star 10 times as massive as the sun will burn through its fuel supply in 20 million years, while a star with half the sun's mass will last more than 20 billion years. The mass also affects the brightness, or luminosity, of a star; more massive stars are brighter. 

Known as Population III stars, the first stars were massive and short-lived. They contained only hydrogen and helium, but through fusion began to create the elements that would help to build the next generation of stars.

 

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Since 2011, Tabby's Star has remained a puzzle. Scientists have come up with various theories, including those involving aliens, to explain its odd behaviour.

Larger and brighter than the Sun, Tabby's Star is located approximately 1.500 light-years from Earth. It exhibits unusual light fluctuations, including up to a 22% dimming in brightness. Typically, a stars periodic changes in brightness is caused by orbiting planets or is due to pulsations in the stellar atmosphere. As planets pass between their stars and Earth, they cause brief and predictable blips in their stars light (usually less than 1 % dimming). But the dips from Tabby's Star appear to be more intense and almost entirely random.

Astronomers are yet to come up with a reasonable explanation for this oddity. Hypotheses range from the presence of a group of comets orbiting the star to debris from disintegrating moon impairing our view of Tabby's Star.

At one time, scientists were seriously considering the possibility that our view was being obstructed by an alien mega-structure, something in the lines of a Dyson Sphere. A Dyson Sphere is a hypothetical mega-engineering project, set up around a star by an advanced extraterrestrial civilisation to capture and use its power output.

What's the latest theory? That there are clouds of dust drifting between us and the star, obscuring our view and causing the blips. But it doesn't explain everything. Scientists are still looking for a more convincing explanation. Hence, the Tabby's Star mystery continues...

 

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The Arecibo message is a 1974 interstellar radio message carrying basic information about humanity and Earth sent to globular star cluster M13. It was meant as a demonstration of human technological achievement, rather than a real attempt to enter into a conversation with extraterrestrials.

The message was broadcast into space a single time via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo radio telescope in Puerto Rico on 16 November 1974. The message was aimed at the current location of M13 about 25,000 light years away because M13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony. The message forms the image shown here when translated into graphics, characters, and spaces.

The message is a series of 1,679 bits that were arranged into 73 lines of 23 characters per line. Let us tell you that these are both prime numbers, and may help the aliens decode the message. It was sent to a cluster of stars 25,000 light-years away from the earth.

There are seven parts in the message from top to down which can show the numbers one to 10, atomic numbers of elements including hydrogen and oxygen, the formulas for the sugars and bases in the nucleotides of DNA, a graphic of the DNA double helix structure, a figure of a human and the population of the earth at the time, a graph of the solar system and a graph of the telescope.

 

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The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University, et. al. Dr. Sagan and his associates assembled 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals. To this they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim.

Each record is encased in a protective aluminum jacket, together with a cartridge and a needle. Instructions, in symbolic language, explain the origin of the spacecraft and indicate how the record is to be played. The 115 images are encoded in analog form. The remainder of the record is in audio, designed to be played at 16-2/3 revolutions per minute. It contains the spoken greetings, beginning with Akkadian, which was spoken in Sumer about six thousand years ago, and ending with Wu, a modern Chinese dialect. Following the section on the sounds of Earth, there is an eclectic 90-minute selection of music, including both Eastern and Western classics and a variety of ethnic music. Once the Voyager spacecraft leave the solar system (by 1990, both will be beyond the orbit of Pluto), they will find themselves in empty space. It will be forty thousand years before they make a close approach to any other planetary system. As Carl Sagan has noted, "The spacecraft will be encountered and the record played only if there are advanced spacefaring civilizations in interstellar space. But the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet."

 

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Hawking, who was so much in tune with the universe, has repeatedly warned humans about threats during recent years. As the genius departs, a look at some of his biggest warnings for man and earth.

2017 saw the launch of one of the biggest searches for extraterrestrial life—Breakthrough Listen Project—which scans the universe for radio signals. Though funded by Hawking, he had a word of caution for seekers of intelligent life who want to communicate with them. Reaching out to advanced civilisations could put earth in a risky position.

"As I grow older I am more convinced than ever that we are not alone. After a lifetime of wondering, I am helping to lead a new global effort to find out," Hawking says in the film while exploring Gliese 832c, a planet that lies 16 light-years away and might foster alien life.

"The Breakthrough Listen project will scan the nearest million stars for signs of life, but I know just the place to start looking. One day we might receive a signal from a planet like Gliese 832c, but we should be wary of answering back," he said in an online film titled Stephen Hawking's Favourite Places.

Hawking likens our encounter with aliens to that of the Native Americans meeting Christopher Columbus—it didn't “turn out so well”. Hawking has warned that if an alien civilisation can pick up our signals, they might have the potential to be billions of years more advanced than humans, making us soft targets for an invasion.

 

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The orange suits (affectionately called pumpkin suits) are not spacesuits. They are worn only while inside a vehicle that is ascending or descending through the atmosphere. Their primary purpose is to protect the crew member from the adverse effects of a depressurization inside the vehicle. They are orange because orange creates a high contrast against the background for rescue crews looking for the crew members in the water or on land.

The current white suits are spacesuits. They are designed for use outside the vehicle, in the vacuum of space. They are designed to provide a pressurized environment, thermal control, and protection against tears and punctures. The suits are white because of emittance. A spacesuit is a thermal system. It is therefore designed to balance the flow of heat into and out of the system. The heat from the Sun is part of the equation, but it is not the full equation. The human being and electrical equipment that is inside the suit is also producing heat and that (excess) heat needs to be rejected.

 

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Your parents would advise you against sharing your location with strangers. But back then, scientists thought it would be a good idea to reach out to aliens by sending out a map to locate our Sun and thereby Earth. What's this map like? in space, no one can find you using coordinates such as north, south, east or west. That's why American astronomer Frank Drake came up with the Pulsar Map. And two of these maps are currently aboard Voyager 1 and 2 probes, which are sailing through the interstellar space. The maps are inscribed on the Golden Record that the probes carry. The records contain sounds and images selected to portray the diversity of life and culture on Earth, intended for any intelligent extraterrestrial life for that may find them.

How does it work?

The pulsar maps on the Voyager probes pinpoint the location of the Solar System with respect to 14 pulsars.

Pulsars are the rapidly spinning remains of dying stars - the leftover cores of supernova explosions. They emit narrow beams of light. Each pulsar has its own signature pulse rate, thus easily identifiable, and ideal as reference points on a map.

Frank Drake's map has each pulsar connected to the Sun by a solid line. The length of the line represents the pulsars approximate relative distance from the Sun. Along those distance markers are inscribed the pulsars' spin rates in binary code. By decoding the map, extraterrestrial intelligence can calculate the time frame of the spacecraft's launch and also the position of the Sun.

 

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Earth is not just a solid ball. It’s interior, as much as its exterior, is a subject of great fascination. You must be aware that Earth's interior has three major layers: the crust, the mantle, and the core. But did you know there is a vast reservoir of water, three times the volume of all the oceans, deep in the Earth's mantle?

It is hidden inside a blue rock called ringwoodite and lies 700 km underground in an area called the transition zone in the mantle, the layer of hot rock between the crust and core. Ringwoodite is a rare mineral that forms under very high pressure and temperature, such as those present in the mantle's transition zone.

The reservoir was discovered in 2014 and it threw new light on the origin of Earth's water. All along, geologists had thought water came from icy comets as they struck the planet during its formation. But the discovery supports an alternative idea that the oceans came from within the interior of early Earth.

The hidden water could also act as a buffer for the oceans on the surface, explaining why they have stayed the same size for millions of years.

 

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The human body is made up of four fundamental elements: carbon, hydrogen, oxygen and nitrogen (also called the CHON or HONC elements). So are rocks, plants, animals, water and air. Do you know where these elements came from? The STARS. Yes, even the calcium in your bone and iron in your blood came from the distant stars. In fact, every atom in your body was forged in the centre of stars years ago. Read on to know how...

When the universe began 13 or 14 billion years ago, with the Big Bang, the only elements that existed were hydrogen, helium and a small amount of lithium. Over time, gravity increasingly pulled gas molecules towards each other and eventually gave birth to the first generation of stars. These stars were much greater than our Sun in size and temperature. The nuclear fusion within those stars then produced heavier elements, including carbon, oxygen, and nitrogen. When the stars exploded in supernova at the end of their life-cycle, the elements were shot into the far-flung reaches of the universe. Those stellar explosions continued, making new stars and planets. As more, massive stars exploded heavier elements continued to be created. Stars and elements are still being born this way, even as you read this.

As far as our galaxy, Milky Way, is concerned, stars had generated most elements now present on Earth about 5 billion years ago. Within the next billion years, the first signs of life on Earth appeared. No one is exactly sure how life formed on the planet. But one thing is clear like Carl Sagan said. "The cosmos is also within us, we're made of star stuff.

 

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A commercial cargo spacecraft bound for the International Space Station (ISS) has been named after NASA astronaut, Kalpana Chawla, the first India-born woman to enter space. Northrop Grumman, an American aerospace and defence technology company, announced that its next Cygnus capsule will be named the “S.S. Kalpana Chawla”, in memory of the mission specialist who died with her six crewmates aboard the space shuttle Columbia in 2003. “Chawla’s final research conducted onboard Columbia helped us understand astronaut health and safety during spaceflight. Northrop Grumman is proud to celebrate the life of Kalpana Chawla and her dream of flying through the air and in space,” the company said.

Born in Haryana, India, Chawla moved to the United States to earn her master's and doctorate degrees in aerospace engineering from the University of Texas in 1984 and the University of Colorado in 1988, respectively.

She then began her career at NASA, conducting research in fluid dynamics at the Ames Research Center in California. After becoming a naturalized US citizen, Chawla applied for and became a NASA astronaut as a member of "The Flying Escargot," NASA`s 15th class of trainees.

 

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