My Science School

On February 5, 1971, Apollo 14 made a successful landing on the lunar surface, thereby becoming the third human landing on the moon after Apollo 11 and Apollo 12.

When we talk about the Apollo programme, it is often hard to look beyond the Apollo 11 mission, which achieved the distinction of landing the first humans on the moon. Even though the Apollo programme is best remembered for this, it should also be noted that it provided for innumerable demonstrations of ingenuity and problem solving and increased NASA's expertise by leaps and bounds.

Following the success of Apollo 11 in July 1969, Apollo 12 landed humans on the moon in November 1969. Apollo 13, however, had to be aborted following an oxygen tank explosion in the service module.

This meant that the Fra Mauro Formation, originally planned to be the lunar landing site for Apollo 13, served as the landing site for Apollo 14, once NASA had completed an accident investigation and upgraded the spacecraft.

Shepard, Mitchell, and Roosa

Launched on January 31, 1971, Apollo 14 had a three-member crew that included commander Alan Shepard, lunar module pilot Edgar Mitchell, and command module pilot Stuart Rossa. Even though there was a potential short circuit in an abort switch on the lunar module and the landing radar came on very late during the landing sequence, Shepard and Mitchell successfully landed on the lunar surface on February 5. In fact, it was the most precise landing until then, as they landed less than 100 feet from the targeted point.

Shepard and Mitchell spent over 33 hours on the moon, including two extra vehicular activities (EVAS) that spanned nine hours and 23 minutes. Even though the first of the two EVAS began an hour later than scheduled due to communications systems problems, it turned out to be a success.

Modular Equipment Transporter

The first EVA was mainly to deploy a number of experiments and some of these sent back data to Earth until September 1977. While a seismometer detected thousands of moonquakes and helped find out the moon's internal structure, other instruments looked at the composition of solar wind and the moon's atmosphere.

Apart from the safety upgrades that were done for Apollo 14, there was also the addition of the Modular Equipment Transporter (MET). While Apollo 11 astronauts carried their tools by hand and Apollo 12 astronauts used a hand tool carrier, Shepard and Mitchell could employ the MET like a wheelbarrow, stowing away their scientific equipment, tools, camera, and sample collections.

During the duo's second EVA dedicated to explore the Cone Crater, the MET came in handy as they were able to pick up a football-sized rock, designated 14321, but better known by its nickname "Big Bertha". Using the MET, the astronauts were able to transport this sample back to the lunar module. As recently as 2019, studies suggested that a two-cm sliver of the Big Bertha might have originally come from the Earth's crust, and not the moon.

42 kg of samples

Even though the crew never saw the interior of the crater, post-mission comparisons showed that Shepard and Mitchell were within 50-75 m from the crater rim. The round trip lasted four hours and 35 minutes in which the duo traversed nearly 3 km, including samples from the first EVA, the duo had collected 42 kg of lunar samples.

While Shepard and Mitchell were busy on the lunar surface, Roosa, who was in the command module, clicked many pictures in high resolution. These photographs of the moon's Descartes region played a pivotal role in certifying the area's safety as a landing site and even helped plan rover traverses for the Apollo 16 mission.

Liftoff from the lunar surface took place exactly on schedule, while rendezvous and docking with the command module was just two minutes off schedule. After spending 2.8 days in lunar orbit, during which time the command module had circled the moon 34 times, the Apollo 14 crew members headed back to Earth. They splashed down safely in the Pacific Ocean on February 9, exactly nine days and two minutes after launch.

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There are many professionals in the field of science who risk their lives for a living. Let's look at a few such professions today

Many seemingly enviable science jobs are fraught with danger. Members of the bomb disposal squad do heroic service by defusing bombs during terrorist attacks. They are well-trained professionals who have expertise in the field, but if they make a slight mistake, the consequences would be disastrous! Interestingly, bomb disposal or mine clearance experts in the British army are known as 'Felix because they are like cats with nine lives!

Scientists researching for vaccines against deadly diseases such as Ebola, Marburg or Anthrax willingly put their lives in great danger. Russian scientist Antonina Presnyakova, working on the Ebola vaccine, died after accidentally sticking herself with a needle laced with the virus.

During the COVID-19 pandemic, as many as over 1,000 doctors died in the line of duty in India alone.

In troubled waters

The job of a diver is indeed extraordinary. Deep sea divers face the possibility of fatal injuries when they are under water, because pressure is very high at depths below 90 metres. They also face the risk of drowning if they run out of oxygen supply before making it back to the water surface.

Diver Rob Robbins dives into the frozen depths of the Antarctic for a living! He assists scientists doing underwater research in the Antarctic. Typically, the scientists have to dive under a 4-6 metres thick ice sheet to study the underwater world. Over the years, Rob and his colleagues have rescued at least a dozen scientists. But there have been casualties too. Although Rob acknowledges that losing sight of the ice hole-the exit point can be terrifying, he enjoys his job thoroughly. He loves the stark contrast: above the ice there is nothing alive, only ice. But when you drop through the hole you are treated to a vibrant, colourful world of sea creatures like a deep red starfish or a soft pink coral.

Playing with fire

For a volcanologist, watching an erupting volcano is an exhilarating experience that far outweighs the risks. Many have had a close brush with death while studying volcanoes. Sonia Calvari can never forget September 13, 1989, when she narrowly escaped death in the volcanic eruptions on Mount Etna in Italy.

But French volcanologists Katia and Maurice Kraft were not so lucky. They died along with 41 others when a fast-moving, massive flow of extremely hot gas and rock erupted from the volcano on Mount Unzen in Japan. Katia and Maurice were often the first to arrive at an active volcano for filming and documenting it.

Diving inside n-reactors

American Charlie Vallance's job involves diving inside nuclear reactors! Nuclear reactors need huge amounts of water in suppression pools to keep the reactor core from melting and also as an emergency coolant. Vallance dives into these massive tanks made of carbon steel to inspect and maintain them. Although water provides a very effective shield against radiation, divers have to take extra precautions while diving into water contaminated with radioactive substances.

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Hundreds of new UFO reports, but...there is still no evidence of aliens. The Pentagon, the headquarters of the United States Department of Defense, has set up a new office to track reports of UFO sightings and collect data.

What are UFOs?

A new Pentagon office set up to track reports of unidentified flying objects (UFOS) has received "several hundreds" of new reports. What are UFOS? Over the centuries, people have reported seeing strange airborne objects or unusual optical phenomena in the sky. These are called UFOS. Over the years, the belief that UFOs are the spaceships of aliens from other planets has gained ground - though without any concrete evidence. Are there possibilities of extraterrestrial life? Shouldn't the sightings be tracked systematically? Well, that's why the All-domain Anomaly Resolution Office (AARO) was formed.

2. What is AARO?

The AARO was set up in July 2022 to track unidentified objects in the sky, underwater and in space. It was established following more than a year of attention on unidentified flying objects that military pilots have observed.

It focusses on unexplained activity around military installations, restricted airspace and "other areas of interest" and is aimed at helping identify possible threats to the safety of U.S. military operations and to national security.

3. Scientific approach

Sean Kirkpatrick, director, AARO, did not rule out the possibility of extraterrestrial life and said he was taking a scientific approach to the research. Since the launch of the AARO, there have been several hundred new reports.

"We are structuring our analysis to be very thorough and rigorous. We will go through it all. And as a physicist, I have to adhere to the scientific method."

4. No alien life

The U.S. military officially calls the 144 sightings observed between 2004 and 2021 as "unidentified aerial phenomena."

But they have seen nothing that indicates alien life. "I have not seen anything that would suggest that there has been an alien visitation, an alien crash or anything like that," said Ronald Moultrie, Under Secretary of Defense for Intelligence and Security.

5. Quick facts

The Air Force conducted an investigation into UFO activity called 'Project Blue Book’. It ended in 1969 with a list of 12,618 sightings, 701 of which involved objects that officially remained "unidentified."

In 1994, it concluded that the 1947 famous "Roswell incident" in New Mexico, was not an UFO but a crashed balloon, the military's long-standing explanation.

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During Earth's journey around the Sun, there are times when its orbit crosses the orbit of a comet. It is when the planet moves through the comet debris trail that we witness meteor showers. The showers are named after the star or constellation which is close to where the meteors appear to radiate in the sky.

All of us may have seen streaks of light zip through the sky. We call them shooting stars and we also wish upon them. Well, what are these shooting stars? What are these streams of light?

Consider the objects in space. These are lumps of rock or objects in space with sizes ranging from grains to small asteroids. A small piece of a comet or asteroid is called a meteoroid.

Meteoroid

These meteoroids can be considered as space rocks. They orbit the sun and when they enter Earth's atmosphere at a high speed, they burn because of frictional heating, causing the light. These rays of light are referred to as meteors.

When many meteors appear at once, we call it a meteor shower. During a meteor shower, a number of meteors can be seen radiating or originating from a point in the night sky.

But where do these meteoroids come from? How does Earth come across these? During Earth's journey around the Sun, there are times when its orbit crosses the orbit of a comet. It is when the planet moves through the comet debris trail that we witness meteor showers.

The meteor showers are named after the star or constellation which is close to where the meteors appear to radiate in the sky.

The Perseids meteor shower is the most famous meteor shower and they peak around August 12 every year.

Other notable meteor showers include the Leonids, Aquarids and Orionids and Taurids.

Now what happens when meteoroid survives the journey through the Earth's atmosphere and hits the ground? In that case, it becomes a meteorite.

Did you know that more than 50,000 meteorites have been found on Earth?

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Researchers have surpassed an important milestone for nuclear fusion technology: getting more energy out than was put in. Some consider this to be the energy of the future since nuclear fusion produces no greenhouse gases and leaves little waste. So, how does it work, what projects are underway, and when could they be completed? Come, let's find out

What is fusion?

Fusion is the process that powers the sun. Two light hydrogen atoms, when they collide at very high speeds, fuse together into one heavier element, helium, releasing energy in the process. (Fusion differs from fission, the technique currently used in nuclear power plants, by fusing two atomic nuclei instead of splitting one.) "Controlling the power source of the stars is the greatest technological challenge humanity has ever undertaken," tweeted physicist Arthur Turrell, author of "The Star Builders".

Creating fusion on Earth

Producing fusion reactions on Earth is possible only by heating matter to extremely high temperatures - over 100 million degrees Celsius. "So we have to find ways to isolate this extremely hot matter from anything that could cool it down. This is the problem of containment." Erik Lefebvre, project leader at the French Atomic Energy Commission (CEA), said.

One method is to "confine" the fusion reaction with magnets. In a huge doughnut shaped reactor, light hydrogen isotopes (deuterium and tritium) are heated until they reach the state of plasma, a very Low density gas. Magnets confine the swirling plasma gas, preventing it from coming into contact with the chambers walls, while the atoms collide and begin fusing. This is the type of reactor used in the major international project known as ITER currently under construction in France, as well as the Joint European Torus (JET) near Oxford, England.

A second method is inertial confinement fusion, in which high energy lasers are directed simultaneously into a thimble-sized cylinder containing the hydrogen (as shown in the graphic). This is the technique used by scientists at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in California, the U.S. who were behind the recent announcement. Inertial confinement is used to demonstrate the physical principles of fusion, while magnetic confinement seeks to mimic future industrial-scale reactors.

What is net energy gain?

For decades, scientists had attempted to achieve what is known as "net energy gain" - in which more energy is produced by the fusion reaction than it takes to activate it.

LLNL director Kim Budil cautioned that much remains to be done before this energy can be commercially viable. "There are very significant hurdles, not just in the science but in technology," Budil said. "A few decades of research on the underlying technologies could put us in a position to build a power plant." To get there, researchers must first increase the efficiency of the lasers and reproduce the experiment more frequently.

Fusion has several benefits, but...

The NIF's success has sparked great excitement in the scientific community, which is hoping the technology could be a game-changer for global energy production.

Unlike fission, fusion carries no risk of nuclear accidents.

"If a few lasers are missing and they don't go off at the right time, or if the confinement of the plasma by the magnetic field... is not perfect," the reaction will simply stop, Lefebvre says.

Nuclear fusion also produces much less radioactive waste than current power plants, and above all, emits no greenhouse gases. "It is an energy source that is totally carbon-free, generates very little waste, and is intrinsically extremely safe," according to Lefebvre, who says fusion could be "a future solution for the world's energy problems".

However, the technology is still a far way off from producing energy on an industrial scale, and cannot therefore be relied on as an immediate solution to the climate crisis.

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Sunspots are regions on the sun that appear dark. They occur in regions where the magnetic field of sun is strong. The temperature of a sunspot is super hot-something around 6,500 degrees Fahrenheit

The Sun, the centre of our solar system and our closest star, is 4.5 billion years old. This fiery glowing orb of hydrogen and helium sustains life as we know it

Sunspots

Sunspots are regions on the sun appear dark. These parts appear darker as they are cooler when compared to other parts of the sun. They occur in regions where the sun's magnetic field is highly concentrated or strong.

The centre of the sunspot is dark and this is called the umbra while the outer and lighter ring is called the penumbra. Spots vary in sizes. They could be larger than the Earth, or so tiny that it will be difficult to pick them up in telescopic observation. The sunspots could stay on for months. Most of the sunspots can be seen in pairs or groups but single spots also do occur. When they occur in pairs, they have opposite magnetic polarity.

Why are sunspots cooler

Sunspots form in areas on the sun where the magnetic field is very strong and powerful. These magnetic fields will prevent the heat within the Sun from reaching its surface. Even when we say that the sunspots are cooler, this is just in comparison to the other regions of the Sun. The temperature of a sunspot is super hot something around 6.500 degrees Fahrenheit.

Why do sunspots matter

 In most cases, sunspots precede the occurrence of a solar flare. Solar flares are sudden bursts or explosions of energy from the sun's surface. This occurs when the magnetic field lines near the sunspots reorganise or cross. These solar flares will release huge amounts of radiation into space. The more intense the solar flare, the more intense will be its radiation. This can affect radio communication on Earth. Studying and monitoring the sunspots are required to understand the reason behind the occurrence of solar flares.

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Scientists have discovered the world's largest-known bacterium, in the form of white filaments the size of human eyelashes, on the surfaces of decaying mangrove leaves in a swamp in Guadeloupe in the Caribbean Sea.

Around 1 cm long, Thiomargarita magnifica is 50 times larger than all other known giant bacteria and the first to be visible with the naked eye. Researchers have compared it to a human encountering another human as tall as Mount Everest.

In most bacteria, the genetic material floats around freely inside the cell. T. magnifica keeps its genetic material inside membrane- bound compartments throughout the cell. It was also found to contain three times as many genes as most bacteria.

The discovery suggests that "large and more complex bacteria may be hiding in plain sight".

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Mercury is the smallest planet in our solar system. Located closest to the Sun, it is also the fastest planet in our solar system, travelling at a speed of nearly 47 kilometres per second. In fact, the closer a planet is to the Sun, the faster it travels. Mercury completes one circle around the Sun in just about 88 Earth-days.

When observed from its surface, the Sun would appear more than three times as large as it does when viewed from Earth, and the sunlight is as much as seven times brighter. But despite this proximity to the Sun, Mercury is not the hottest planet in our solar system- it is Venus. The reason for this is Venus' dense atmosphere.

Another interesting aspect of Mercury is that the Sun appears to rise briefly, set, and rise again from some parts of the planet's surface due to its elliptical and egg-shaped orbit, and sluggish rotation. The same phenomenon happens in reverse during sunset.

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A protogalaxy is in simpler words a primeval galaxy. It refers to a galaxy that is undergoing the first generation of star formation. It is also defined as a cloud of gas that is forming into a galaxy. This particular celestial mass would just comprise hydrogen gas trapped in some dark matter prior to the initial stages of star formation. The stars are formed from the smaller clumps of gas in the protogalaxy.

Types of Galaxies

 There are two types of galaxies viz. elliptical galaxies and spiral galaxies. The majority of the galaxies that you come across are elliptical galaxies and they are called so because they have an even, ellipsoidal shape. They also are comprised with a greater population of older stars when compared to spiral galaxies.

A spiral galaxy normally has a rotating disc replete with spiral 'arms. The stellar orbits are circular in shape and they have a flattened disk system. Most spiral galaxies also contain in their centre a mini-elliptical galaxy. Our galaxy, the Milky Way, is a spiral galaxy.

So what determines the shape of a galaxy? The rate of star formation during galactic evolution determines whether it turns out into a spiral or elliptical galaxy. If the star formation is at a slower pace, then it turns into a spiral galaxy.

Milky Way

About 12.5 billion years ago, the Milky Way started to form. Several huge clusters of stars and clumps of gas fused together to form a protogalaxy. This was the building basis of our home!

It then collided with many galaxies, and after a lot of mergers, it acquired its present form.

Recently, scientists discovered a population of millions of stars at the center of our galaxy. Those were the remains of the ancient protogalaxy! These oldest stars that were found in the core area of our galaxy were analysed and the scientists found out that they were part of a protogalaxy.

The diameter of which extended to 18 thousand light-years, and with a mass that was 50-200 million times that of the Sun!

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The largest planet in our solar system, Jupiter, is located fifth from the Sun. It is more than two times the size of all the planets in our solar system combined. Jupiter has also been instrumental in our understanding of the universe and our place in it. In 1610, Galileo discovered Jupiter's four large moons: lo, Europa, Ganymede and Callisto. This confirmed the Copernican view that the Earth was not the centre of the universe as these newly discovered celestial objects were revolving around another planet.

It is estimated that eleven Earths could fit across Jupiter's equator. To put it in other words, if our planet is the size of a grape, then Jupiter is the size of a basket-ball. It has an iconic Great Red Spot, which is a giant storm that has been active in Jupiter's atmosphere for hundreds of years. This storm is bigger than the Earth!

Jupiter's orbit is about 778 million kilometres or 5.2 Astronomical Units (AU) from the Sun (Earth is one AU from the Sun). Jupiter is a gas giant, which lacks an Earth-like atmosphere. Even if it has a solid inner core at all, it would only be about the size of the Earth. Jupiter's atmosphere contains mainly hydrogen (H) and helium (He) and has more than 75 moons. It rotates about its axis once every 10 hours (a Jovian day), and takes about 12 Earth years to complete one revolution about its orbit around the Sun (a Jovian year).

In the year 1979, NASA's Voyager mission discovered Jupiter's faint ring system. We have discovered that all the four giant planets of our solar system have ring systems. Till date, nine spacecraft have visited Jupiter. Of them, only the most recent one landed on Jupiter. Seven of them only flew by this gas giant and the other two just orbited it. Juno, the latest spacecraft, arrived on Jupiter in 2016.

Although it is the biggest planet in our solar system, Jupiter cannot support life as we know it. But we have come to know that some of its moons have oceans beneath their crusts, which could possibly support some form of life.

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Yes, an air conditioner takes the warm air from inside a room and transfers it outside.

An AC unit takes the warm air from inside a room and transfers it outside. It also consumes electricity which generates further heat.

A Japanese scientist found in 2007 that air conditioners in Tokyo raised the temperature in the city by about 1°C. Surprisingly, the heating effect was more at night than during the day when more air conditioners were used.

This is because the planetary-boundary layer, the part of the atmosphere touching Earth's surface, is thickest during the day. The extra heat produced by ACS disperses upwards. At night, the same layer reduces from a thickness of 3 km to less than 100 metres! So the heat remains closer to the Earth's surface.

Researchers feel the excess heat could be channelled through the city's waste water pipes, since water can dissipate four times as much heat energy as air. This would reduce the heat on the street.

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Researchers find out an often overlooked key role played by the orbit of Jupiter on Earth.

Most planets have eccentric orbits. While circular orbits around a star would ensure that the distance between the star and the planet never changes, these eccentric orbits mean that the planets traverse around a star in an oval-shape. As a result, the planet would receive more heat when it goes closer to the star, affecting the planet's climate.

Alternative solar system

Based on this knowledge and using detailed data from the solar system as we know it today, researchers from the University of California Riverside created an alternative solar system. In this hypothetical theoretical system, they were able to show that if Jupiter's orbit were to become more eccentric, then it would lead to big changes in Earth's orbit, thereby making the Earth more hospitable than it is currently.

This is because Jupiter in this theoretical system would push Earth's orbit to be even more eccentric. As a result, parts of Earth would sometimes get closer to the sun. This would mean that even parts of Earth's surface that are now sub-freezing will get warmer. In effect, the habitable range on the surface of the Earth would be increased.

Assumptions proven wrong

 The findings of this research, published in September in Astronomical Journal, go against two long-held scientific beliefs with respect to our solar system. One of these is that the current avatar of Earth is the best in terms of habitability. The second one is that changes to Jupiter's orbit could only be bad for Earth.

Apart from upending these long-held assumptions, the researchers are looking to apply their findings in the search of exoplanets - habitable planets around other stars. While existing telescopes are adept at measuring a planet's orbit, the same cannot be said about measuring a planet's tilt towards or away from a star- another factor that could affect habitability.

The model developed in this research helps us better understand the impact of the biggest planet in our solar system, Jupiter, on Earth's climate through time. Additionally, it also paves the way to find out how the movement of a giant planet is crucial in making predictions about habitability of planets in other systems.

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As their name suggests, dwarf galaxies are smaller galaxies. In contrast to a normal galaxy that comprises hundreds of billions of stars, a dwarf galaxy would contain just about a few billion stars. These dwarf galaxies orbit larger galaxies after their formation.

Formation of dwarf galaxies

The dwarf galaxies are created when two galaxies collide, fromed from the material and dark matter coming out of the galaxies that collided.

Following these collisions, while a significant portion of the gas, dust and stars emitted gets reincorporated into the galaxy created after the collision, some can lead to the formation of dwarf galaxies which then orbit around the galaxy. They are also formed by the gravitational forces existing during the creation of these larger galaxies.

Why are dwarf galaxies crucial

Scientists consider the dwarf galaxies critical as they could help gain insight into the early stages of the formation of galaxies and stars. According to scientists, our galaxy has about 14 satellite dwarf galaxies orbiting it.

Studies are being carried out on these dwarf galaxies as it would give us clues regarding the evolution of the galaxies. By studying the motion of the stars in these galaxies, we would also get to know more about dark matter and how it is distributed in the galaxies.

It is difficult to spot dwarf galaxies as they are less bright when compared to larger galaxies. A large number of them can be spotted in galaxy clusters or as a companion to larger galaxies.

Shapes of dwarf galaxies

The dwarf galaxies take several shapes. The dwarf elliptical galaxies are quite similar to normal elliptical galaxies.

Then there are dwarf spheroidal galaxies which are more spherical in shape and smaller when compared to the former.

Then we have the irregular dwarf galaxies. They do not have a distinct structure and are rich in gas.

One of the closest dwarf galaxies to the Milky Way is the Sagittarius Dwarf Spheroidal Galaxy.

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When the Apple fell on Newton or when Archimedes took a bath, history as we know it changed. Those are the 'Aha' moments when scientific discoveries were made. A look at some of these breakthrough moments.

Archimedes' principle - Archimedes

This was history's first-ever 'Eureka' moment. The story of how the Greek mathematician Archimedes discovered the principle of buoyancy is a tale worth recounting. It was whilst taking a bath in a tub that the idea hit Archimedes. When Archimedes noticed the amount of water being displaced from the tub as soon as he entered it, he reasoned that the volume of the water displaced is equal to the volume of the body that was submerged. He is said to have run across the streets naked, shrieking "Eureka" at his discovery of the law of buoyancy. And that gave us the Archimedes' principle.

Periodic Table - Dmitri Mendeleev

For Russian chemist Dmitri Mendeleev, it all happened in a dream. The Periodic Table of Elements as we know it was conceptualised in a dream. For months, he was trying to arrive at a logical way to organise the chemical elements. Although he knew the atomic weight was a crucial element, he couldn't find a way to arrange it. One day, after racking his brain over the arrangement pattern, he fell asleep. And lo, the periodic table was born. The idea for the logical arrangement of the elements dawned on him during his dream. He later wrote "In a dream, I saw a table where all the elements fell into place as required."

Law of Gravity - Isaac Newton

Every child grew up listening to the tale of how an apple's fall changed science. It was when Isaac Newton noticed the apple fall that he first got the idea of gravity. He wondered what force attracted everything towards the Earth. The tree that inspired the idea of gravity in Newton still stands in the garden of Newton's old home.

Penicillin - Dr. Alexander Fleming

The discovery of penicillin, the world's first antibiotic, revolutionised the course of medicine. Dr. Alexander Fleming had just returned from a holiday and found mould growing on a petri dish of Staphylococcus bacteria. The green mould Penicillium notatum prevented the bacteria around it from growing. He isolated the mould, and understood it produced a substance that could kill the bacteria. He named the active agent penicillin and thus the world's first antibiotic was discovered.

First synthetic dye - William Perkin

The fashion industry must thank William Perkin for his discovery of the first synthetic dye. He was trying to find a cure for malaria, but he accidentally invented the first synthetic purple dye. Perkin was assisting German chemist August Wilhelm von Hofmann in the process of using coal tar to produce quinine which was an expensive anti-malarial drug. As he mixed different coal tar components with potassium dichromate and sulphuric acid, Perkin produced a purple sludge. The rest is history.

DID YOU KNOW? Newton recounted the story that inspired his theory of gravitation to scholar William Stukeley. It appeared in Stukeley's 1752 biography, "Memoirs of Sir Isaac Newton's Life." The UK's Royal Society converted the fragile manuscript into an electronic book in 2010 and made it accessible online to the public.

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Discovered on August 28, 1789, Enceladus is a natural satellite of Saturn. This moon, which remained in relative obscurity for nearly 200 years, is now one of the most scientifically interesting destinations in our solar system.

The possibility of worlds other than our own Earth where life could exist has enthralled us for a long time. Often seen in the realm of science fiction, we might be inching ever so closer to it in reality as scientists have identified a handful of worlds that have some of the ingredients needed for life. One of them is Enceladus, an icy moon that is the brightest in the solar system.

Enceladus was discovered on August 28, 1789 by British astronomer William Herschel, more popular for discovering the planet Uranus. Little is known about how William went about it and made his discovery.

A dwarf named after a giant

What we do know, however, is that it was William's son, John Herschel, who gave the moon its name Enceladus, after the giant Enceladus of Greek mythology. In his 1847 publication Results of Astronomical Observation made at the Cape of Good Hope, John suggested names for the first seven moons of Saturn that had been discovered, including Enceladus. He picked these particular names as Saturn, known in Greek mythology as Cronus, was the leader of the Titans.

For nearly two centuries, very little was known about Enceladus. That changed in the 1980s, when the U.S. spacecrafts Voyager 1 and Voyager 2 flew by the moon, capturing images. The pictures indicated that the icy surface of this small moon is very smooth in some places and bright white all over.

Enceladus, in fact, is the most reflective body in the solar system. Scientists, however, didn't know why this was the case for a few more decades. Enceladus reflective capability implies that it reflects almost all the sunlight that strikes it, leading to extremely cold surface temperatures, of the order of -200 degree Celsius.

E ring and tiger stripes

Shortly after NASA's Cassini spacecraft began studying Saturn's system in 2004, Enceladus started revealing its secrets. By spending over a decade in the vicinity of the small moon, including flybys as close as 50 km, Cassini was able to unearth a wealth of information about Enceladus.

Cassini discovered that icy water particles and gas gush from the moon's surface at about 400 metres per second. These continuous eruptions create a halo of fine dust around the moon, which supplies material for Saturn's E ring. While a small fraction of this remains in the ring, the remaining falls like snow back onto the moon's surface, thereby making it bright white. Scientists informally call the warm fractures on Enceladus' crust from which the water jets come from as "tiger stripes".

By measuring the moon's slight wobble as it orbits Saturn and from gravity measurements based on the Doppler effect, scientists were able to determine that these jets were being supplied by a global ocean inside the moon. As this ocean supplies the jet, which in turn produces Saturn's E ring, it follows that studying material from the E ring is akin to studying Enceladus' ocean.

While the E ring is mostly made of ice droplets, there is also the presence of nanograins of silica that can be generated only where liquid water and rock interact at temperatures above 90 degrees Celsius. Along with other evidence that has been gathered, this suggests the existence of hydrothermal vents deep beneath this moon's shell, similar to those on the Earth's ocean floor.

Orbital resonance

Enceladus takes 33 hours for its trip around Saturn, which is nearly half of the time taken by the more distant moon Dione. Enceladus is thus trapped in an orbital resonance with Dione, whose gravity stretches Enceladus' orbit into an elliptical shape. This means that Enceladus is sometimes closer to Saturn and at other times farther leading to tidal heating within the moon.

Running just over 500 km across, Enceladus is small enough to fit within the Indian State of Maharashtra, which runs around 700 km north-south and 800 km east-west. What it lacks in size it more than makes up for in stature, as Enceladus has a global ocean, unique chemistry, and internal heat. All this means that even though we still have plenty of data about the moon to pore over, explorers will eventually plan a return to Enceladus to learn more of its secrets.

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