There are three different ways to pronounce the ‘ED’ ending of regular verbs in the simple past tense: / t/ , / d / or / id /. The pronunciation depends on the sound at the end of the infinitive of the main verb and whether it is voiced or not. A voiced sound is one that vibrates in your throat when you say it.
A deafening boom roars through Pompeii’s crowded marketplace. The ground shakes violently, throwing midday shoppers off balance and toppling stands of fish and meat. People scream and point toward Mount Vesuvius, a massivevolcanothat rises above them.
Nearly 2,000 years ago, Pompeii was a bustling (busy) city located in what is now southernItaly.
But in the summer of A.D. 79, the nearby Mount Vesuvius volcano erupted. It spewed smoke and toxic gas 20 miles into the air, which soon spread to the town. Almost overnight, Pompeii—and many of its 10,000 residents—vanished under a blanket of ash.
Pompeii was basically lost and forgotten until it was rediscovered in 1748. Thanks to excavations, which are still going on today, scientists have been able to figure out almost exactly what happened on that terrible day.
THE SKY IS FALLING
After the volcano first erupted shortly after noon, the thick ash turned everything black—people couldn’t even see the sun. Some residents escaped the city, while others took shelter in their homes. But the ash kept falling. Piles grew as deep as nine feet (3 meters) in some places, blocking doorways and caving in roofs.
Around midnight, the first of four searing-hot (300 degrees Celsius) clouds of ash, rock, and toxic gas (also called surges) rushed down the volcano. Traveling toward Pompeii at about 180 miles an hour (290 km/h), the surge scorched everything in its path. Around 7 a.m., nearly 19 hours after the initial eruption, the city was completely covered in a deadly mix of ash and rock.
LOST AND FOUND
Visiting the ruins of Pompeii is like going back in time. The layers of ash actually helped preserve buildings, artwork, and even the forms of bodies as they decomposed and left holes in the ash. All that allowed experts to fill in the details that might not have survived at many other Roman sites.
Based on what they uncovered, scientists believe that Pompeii was a prosperous town popular with wealthy vacationing Romans. Well-paved streets had high sidewalks and stepping-stones to keep pedestrians out of the mud. To relax, people soaked in public baths, watched gladiators or chariot races at an amphitheater, and enjoyed plays in two theaters.
Pompeii may be ancient history, but scientists are pretty sure Mount Vesuvius is overdue for another major explosion. Luckily the people living near the volcano today will likely receive evacuation warnings before it blows.
Humans have thought about flying for a long, long time. For example, there is the Greek myth of Icarus from 3,000 years ago. (A myth is an old story, often with gods and magic. )
In the Greek myth, Daedalus made wings from feathers held together with wax for himself and his son so that they could escape from an island. He flew successfully from the island of Crete to the city of Naples, but Icarus tried to fly too high and flew too near to the sun, even though Daedalus told him not to fly towards the sun. The wings of wax melted and Icarus fell to his death in the ocean.
In another Greek myth, Bellerophon the Valiant, son of the King of Corinth, captured Pegasus, a winged horse. Pegasus flew him to a battle with the three-headed monster, Chimera.
Pegasus is shown on a Greek vase from around 500 BC. (Museum of Fine Arts, Boston)
Early Research into Flight
The story of the invention of the airplane begins in the 16th, 17th, and 18th centuries, with the first serious research into aerodynamics. Aerodynamics is the way objects move through air (for instance, a wing when it is immersed in a stream of air).
Some of Leonardo's drawings of a "flying machine"
Leonardo da Vinci made the first real studies of flight in the 1480s. He had over 200 drawings and sketches that illustrated his theories on flight. His flying machine was an aircraft that would fly by flapping its wings, a design he created to show how humans could fly. However, he never built this. Leonardo was clearly inspired by the flight of winged animals. In his notes, he mentions bats, kites, and birds as sources of inspiration.
The San Diego Air and Space Museum’s display is a model of one of Leonardo da Vinci’s designs based on his drawings.
Others, such as Galileo Galilei (died 1642) in Italy, Christiaan Huygens in the Netherlands, and Isaac Newton (died 1727) in England worked to understand the movement of air and liquids across surfaces.
Kites
The invention of the kite that could fly in the air by the Chinese started humans thinking about flying. Starting around 400 BC, kites were used by the Chinese in religious ceremonies. They built many colorful kites for fun, also. More sophisticated kites were used to test weather conditions. Kites have been important to the invention of flight as they were the forerunner to balloons and gliders.
The First Hot Air Balloons
The brothers Joseph Michel and Jacques Etienne Montgolfier, who lived in France, were inventors of the first hot air balloon. They used the smoke from a fire to blow hot air into a silk bag. The silk bag was attached to a basket. The hot air then rose and allowed the balloon to be lighter-than-air.
In 1783, the first passengers in the colorful balloon were a sheep, rooster and duck. It climbed to a height of about 6,000 feet (1828.8 meters) and traveled more than 1 mile (1.6 km).
After this first success, the brothers began to send men up in balloons. The first manned flight was on November 21, 1783. The passengers were Jean-François Pilatre de Rozier and François Laurent.
The first free ascent (no rope to the ground) of a hot-air balloon with human passengers, on Nov. 21, 1783. — Jean-François Pilâtre de Rozier and the Marquis d´Arlandes (François Laurent) (Image credit: 2001 National Air and Space Museum, Smithsonian Institution)
Hot air balloons today
Understanding Flight
In the 19th century, mathematicians, engineers and inventors tried to understand the science of flight.
German engineer Otto Lilienthal studied aerodynamics and worked to design a glider that would fly. He was the first person to design a glider that could fly a person and was able to fly long distances. He was fascinated by the idea of flight. Based on his studies of birds and how they fly, he wrote a book on aerodynamics that was published in 1889 and this text was used by the Wright Brothers as the basis for their designs. After more than 2,500 flights, he was killed when he lost control because of a sudden strong wind and crashed into the ground.
German aviation pioneer Otto Lilienthal piloting one of his gliders, around 1895. It did not have an engine, so it was not an airplane.
The videos below shows some of the earliest airplanes from about 1900 to 1920 that did not work.
Planes that did not work
Here are some early attempts at making flying machines.
Finally! The Airplane!
Finally, in 1903, in the United States of America, an airplane flew! The Wright Flyer (also known as the Kitty Hawk,Flyer I or the 1903 Flyer) made the first sustained flight by a manned heavier-than-air powered and controlled aircraft—an airplane—on December 17, 1903. Invented and flown by brothers Orville and Wilbur Wright, it marked the beginning of the pioneer era of aviation.
The first Wright Flyer traveled one hundred twenty feet (36.6 meters) in twelve seconds. The two brothers took turns flying that day with the fourth and last flight covering 850 feet (259 meters) in 59 seconds. But the Flyer was unstable and very hard to control.
The brothers worked for two more years perfecting their design. Finally, on October 5, 1905, Wilbur piloted the Flyer III for 39 minutes and about 24 miles (38 km) of circles. He flew the first working airplane until it ran out of gas.
Humankind was now able to fly! During the next century, many new airplanes and engines were developed to help transport people, luggage, cargo, military personnel and weapons. The 20th century's advances were all based on this first flights by the American Wright brothers.
Orville was at the controls of the machine, lying on the lower wing with his hips in the cradle which operated the wing-warping mechanism. Wilbur Wright ran alongside to balance the machine, and just released his hold on the forward upright of the right wing in the photo.
The driest place on Earth is in Antarctica in an area called the Dry Valleys, which have seen no rain for nearly 2 million years. There is absolutely no precipitation(snow or rain) in this region and it makes up a 4,800 square kilometer region of almost no water, ice or snow. Water features include Lake Vida, Lake Vanda, Lake Bonney and the Onyx River.
There is no net gain of water(the amount of water does not increase). The reason why this region receives no precipitation is because of Katabatic winds, winds from the mountains that are so heavy with moisture that gravity pulls those winds down and away from the Valleys.
One feature of interest is Lake Bonney, a saline (salt) lake situated in the Dry Valleys. It is permanently covered with 3 to 5 meters of ice. Scientists have found mummified(dried and frozen) bodies of seals around the lake. Lake Vanda, also in the region, is 3 times saltier than the ocean. Temperatures at the bottom of this lake are as warm as 25 degrees Celsius.
The Dry Valleys are one of the most extreme desert climates anywhere on earth, a cold desert where the mean annual temperature is between -14C and -30C depending on the site -- windier sites are less cold. An area of the world is called a desert if it has little rain or snowfall. Deserts can be hot (like the Sahara)orcold (like the Antarctic).
(Mean annual temperature - The mean is the average of the numbers and is calculated by dividing the sum of the numbers by the total number of numbers. For example: the mean of 5, 10, 15 is the numbers added up (30) and then divided by the number of numbers (3), so the mean is 10.)
Knowing the difference between "mean" and "median" (the middle number in a series of numbers) can be very useful. - Derek)
Bull Pass, above, in the Dry Valleys. The temperature in the ice and snow-free area is little or no different to the adjacent ice-covered regions, the local geography accounts for the absence of ice.
The next driest place in the world measured by the amount of precipitation that falls is the Atacama Desert in Chile and Peru. There are no glaciers that are feeding water to this area; and thus, very little life can survive. Some weather stations in this region have received no rain for years, while another station reports an average of one millimeter per year.
Squids, octopuses, and cuttlefishes are among the few animals in the world that can change the color of their skin very fast. These cephalopods—a group of mollusks (mollusks are animals like octopuses, oysters, and snails) with arms attached to their heads—can change their skin tone (color, darkness and lightness) to match their surroundings, making them nearly invisible, or give themselves a pattern that makes them easily seen.
Camouflage is the way in which some animals are colored and shaped so that they cannot easily be seen in their natural surroundings.
Many thousands of color-changing cells called chromatophores just below the surface of the skin are responsible for these amazing changes. The center of each chromatophore contains an elastic sac full of pigment (color), rather like a tiny balloon, which may be colored black, brown, orange, red or yellow. If you stretched a dye-filled balloon, the color would gather in one spot, stretching out the surface and making the color appear brighter—and this is the same way chromatophores work. Nerves and muscles control whether the sac is expanded or contracted and, when the sac expands, the color is more visible.
Besides chromatophores, some cephalopods also have iridophores and leucophores. Iridophores have stacks of reflecting plates that create iridescent (shiny like metal) greens, blues, silvers and golds, while leucophores mirror back the colors of the environment (what is around the animal - rocks, sand, etc.), making the animal less conspicuous (less easily seen).
The most obvious reason such a soft-bodied animal (an animal without bones) would change color is to hide from predators (animals that will eat it)—and octopuses are very good at this. They can change not only their coloring, but also the texture of their skin to match rocks, corals and other items nearby. They do this by controlling the size of projections (bumps) on their skin, creating textures ranging from small bumps to tall spikes. The result is a disguise that makes them nearly invisible.
An camouflaged octopus becomes visible suddenly and squirts ink as it swims quickly away
Color changing is just one of an octopus’s defenses, however; it can also spray ink (watch the video above), and make a quick escape through any hole it can get its hidden bony beak through (octopuses have beaks like birds such as parrots).
Intelligence is another way an octopus can defend itself. We'll look at how smart octopuses are in another blog post. This short video will give you an idea of how smart they are. - Derek
Mollusks or Molluscs are a group of soft-bodied invertebrates distributed across ocean, freshwater, and land habitats.
Tardigrades are microscopic eight-legged animals that have been to outer space and would likely survive the apocalypse(the end of the world). Bonus: They look like adorable (lovable) miniature bears.
Around 1,300 species of tardigrades are found worldwide. Considered aquatic because they require a thin layer of water around their bodies to prevent dehydration, they’ve also been observed in all kinds of environments, from the deep sea to sand dunes. Freshwater mosses and lichens are their preferred habitat (place they live), therefore their nickname, moss piglet.
Despite looking squishy(very soft), tardigrades are covered in a tough cuticle, similar to the exoskeletons of grasshoppers, praying mantises, and other insects to which they are related. Like those insects, tardigrades have to shed their cuticles in order to grow. They have four to six claws on each foot, which helps them cling to plant matter, and a specialized mouthpart called a bucco pharyngeal apparatus, which allows them to suck nutrients from plants and microorganisms.
Tiny and tough
Tardigrades belong to an elite category of animals known as extremophiles, or critters (animals) that can survive environments that most others can't. For instance, tardigrades can go up to 30 years without food or water. They can also live at temperatures as cold as absolute zero (-273.15 degrees Celsius) or above boiling (100 degrees Celsius), at pressures six times that of the ocean’s deepest trenches, and in the vacuum of space.
Another amazing survival trick is cryptobiosis, a state of inactivity triggered by a dry environment. The micro-animals squeeze all the water out of their bodies, retract (pull in)their heads and limbs(legs), roll up into a little ball, and become dormant(having normal physical functions suspended or slowed down for a period of time; as if in a deep sleep). When conditions improve, they unfurl (unroll) themselves and go about their business(live normally).
Mating and reproduction
Naturally, tardigrades have unusual mating habits, too. Depending on the species, the animals may reproduce asexually (without having sex) or sexually. In some species, males deposit sperm inside the cuticle of a molting, egg-carrying female during an hour-long mating process. Some females shed their cuticle and then lay their eggs inside to be fertilized later by males.
Eggs take around 40 days to hatch, or as long as 90 days if they’ve been in a desiccated (very dry) state.
DID YOU KNOW
Tardigrades have been on earth about 600 million years, preceding the dinosaurs by about 400 million years.
The Israeli spacecraft Beresheet was carrying thousands of tardigrades when it crash-landed on the moon in April 2019. Later experiments show the animals likely died on impact.
swindler - a criminal who tricks people and takes their money
weaver - someone who makes cloth
loom - a machine for making cloth
fabric - cloth
invisible - if something is invisible, you can't see it
This is a fairy story written about 200 years ago by the famous author Hans Christian Anderson. Anderson was from Denmark. His most well-known story is the Little Mermaid, which has been made into a movie.
Many years ago, there was an Emperor who loved new clothes so much that he spent all his money on being well dressed. He didn't care about ordering his soldiers to get into lines so that he could walk around and look at them, or going to the theatre, or going for a ride in his carriage, except to show off his new clothes.
He had a coat for every hour of the day, and instead of saying, as people might, about any other emperor, "The Emperor is having a meeting about important matters," here they always said, "The Emperor's in his dressing room, looking at himself in the mirror."
In the great city where he lived, life was always bright and happy. Every day many strangers came to town, and among them one day came two swindlers, criminals who liked to trick people into giving them money. They lied to get money.
The swindlers laughing about fooling the Emperor
These swindlers told people that they were weavers, makers of beautiful clothes, and they said they could weave the best fabrics imaginable. They told the Emperor that not only were their colors and patterns very nice, but clothes made of this cloth had a wonderful way of becoming invisible to anyone who could not do his job, or who was unusually stupid. These people would not be able to see the weavers' cloth.
A loom used to make cloth
They set up two looms and pretended to weave, though there was nothing on the looms. All the finest silk and the purest gold thread which they demanded from the Emperor they kept for themselves. They put the silk and gold thread into their traveling bags so that they could make money with it later, while they worked the empty looms far into the night.
"I'd like to know what those weavers are doing with the cloth," the Emperor thought, but he felt slightly uncomfortable when he remembered that those who were not good enough to do their jobs would not be able to see the cloth. It couldn't have been that he doubted himself, but he thought he'd rather send someone else to see how things were going. The whole town believed that the cloth had a strange power, and everybody wanted to find out how stupid their neighbors were.
"I'll send my honest old minister to the weavers," the Emperor decided. "He'll be the best one to tell me if the cloth is good, for he's a smart man who is the best at his job." So the honest old minister went to the room where the two swindlers sat working away at their empty looms.
"Oh no!" he thought as his eyes opened very wide, "I can't see anything at all". But he did not say so.
Both the swindlers asked him to come near to approve the excellent pattern and the beautiful colors. They pointed to the empty looms, and the poor old minister stared as hard as he could. He couldn't see anything, because there was nothing to see. H thought, "Can it be that I'm a fool? I'd have never guessed it, and nobody must know. If I can't see the cloth, does that mean that I am no good at my government job? It would be bad to say that I can't see the cloth."
"Please tell us what you think of the cloth," said one of the swindlers.
"Oh, it's beautiful - it's enchanting." The old minister peered through his spectacles. "Such a pattern, what colors!" I'll be sure to tell the Emperor how very happy I am with it."
"We're pleased to hear that," the swindlers said. They proceeded to name all the colors and to explain the pattern. The old minister paid the closest attention, so that he could tell it all to the Emperor. And so he did.
The swindlers at once asked for more money, more silk and gold thread, to continue with the weaving. But they kept it all for themselves and did not make any cloth. Not a thread went into the looms, though they worked at their weaving as hard as ever.
The Emperor soon sent another trustworthy official to see how the work was going and how soon it would be ready. The same thing happened to him that had happened to the minister. He looked and he looked, but as there was no cloth to see in the looms, he couldn't see anything.
"Isn't it a beautiful piece of cloth?" the swindlers asked him, as they displayed and described their imaginary pattern.
"I know I'm not stupid," the man thought, "so it must be that I'm unworthy of my good office. That's strange. I mustn't let anyone find it out, though." So he praised the material he did not see. He declared he was delighted (very happy) with the beautiful colors and the lovely pattern. To the Emperor he said, "I liked the cloth so much, I looked at it a long time."
All the town was talking of this really nice cloth, and the Emperor wanted to see it for himself while it was still in the looms. Attended by a group of his men, among whom were his two old trusted officials -- the ones who had been to the weavers --he set out to see the two swindlers. He found them busy weaving, but without a thread in their looms.
"Great!" said the two officials. "Just look, Your Majesty, what colors! What a design!", they said to the Emperor. They pointed to the empty looms, each thinking that the others could see the stuff.
"What's this?" thought the Emperor. "I can't see anything. This is terrible! Am I a fool? Am I not good enough to be the Emperor? What a thing to happen to me!"
"Oh! It's very pretty," he said. "It has my highest approval." And he nodded approval at the empty loom. Nothing could make him say that he couldn't see anything.
His officials stared and stared. None of them saw any cloth, but they all joined the Emperor in loudly saying, "Oh! It's very pretty," and they advised him to wear clothes made of this wonderful cloth especially for the great parade he was soon to lead. "Magnificent! Excellent! Unsurpassed!" all the people said, and everyone did their best to seem well pleased. The Emperor gave each of the swindlers an award.
Before the procession, the swindlers sat up all night pretending to finish the Emperor's new clothes. They acted as if they were taking the cloth off the loom. They made cuts in the air with huge scissors. And at last they said, "Now the Emperor's new clothes are ready for him."
Then the Emperor himself came with his noblest noblemen, and the swindlers each raised an arm as if they were holding something. They said, "These are the trousers, here's the coat, and this is the long cape," naming each piece of clothing. "All of them are as light as a spider web. One would almost think he had nothing on, but that's what makes them so fine."
"Exactly," all the noblemen agreed, though they could see nothing, for there was nothing to see.
"If Your Imperial Majesty will be nice enough to take your clothes off," said the swindlers, "we will help you on with your new ones here in front of the long mirror."
The Emperor undressed, and the swindlers pretended to put his new clothes on him, one garment after another. They took him around the waist and seemed to be fastening something as the Emperor turned round and round before the looking glass.
"How well Your Majesty's new clothes look." He heard all the people saying, "That pattern, so perfect! Those colors, so suitable! It is a magnificent outfit."
Then the minister of parades announced: "Your Majesty's canopy is waiting outside."
"Well, I'm supposed to be ready," the Emperor said, and turned again for one last look in the mirror. "It is a remarkable fit, isn't it?" He seemed to look at his costume with the greatest interest.
The noblemen bent low and reached for the floor as if they were picking up his long cape. Then they pretended to lift and hold it high. They didn't dare admit they had nothing to hold.
So off went the Emperor in procession under his splendid canopy. Everyone in the streets and the windows said, "Oh, how fine are the Emperor's new clothes! Don't they fit him to perfection? And see his long cape!"
Nobody would confess that he couldn't see any clothes on the Emperor, for that would prove him either unfit for his position, or a fool. No costume the Emperor had worn before was ever such a complete success.
"But he hasn't got anything on," a little child said.
And one person whispered to another what the child had said, "The Emperor isn't wearing clothes. A child says he hasn't anything on."
"But he isn't wearing anything!" all the people town said loudly at last.
The Emperor shook, for he thought they were right. But he thought, "This parade has got to go on." So he walked more proudly than ever, as his noblemen held high the long cape that wasn't there at all.
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