My Science School

Did you know that a giant iceberg, more than twice the size of Mumbai, broke off from Antarctica's Brunt Ice Shelf late in February 2021? It wasn't entirely unexpected as scientists with the British Antarctic Survey (BAS) were expecting it for years.

How did it form?

The "North Rift crack, as it is called, is the third major chasm in the last decade to tear across the Brunt ice Shelf (an ice shelf is a large floating platform of ice that forms when a glacier flows down to a coastline and onto the ocean surface). After a major crack formed on the shelf in November 2020, it continued to grow until the iceberg broke off in dramatic fashion on February 26.

Even though such a breaking off is entirely normal and part of how the Antarctic ice shelves work, the North Rift is rather special owing to its size. This iceberg, in fact, has an estimated size of about 1,270 sq.km., more than twice the size of even a huge city like Mumbai (603.4 sq.km.).

Glacier vs iceberg

When large pieces of ice breaks off a glacier, ice calving, or iceberg or glacier calving, takes place. Thus, while glaciers are huge masses of ice that move slowly over landforms, an iceberg refers to the pieces of ice that have broken off either from glaciers or ice shelves and are now floating in open water.

According to a BAS statement, this ice split likely happened due to a natural process and there is no evidence suggesting that climate change had a role to play.

Glaciological structure of this vast floating ice shelf, however, is very complex and predicting the impact of such calving events is rather difficult.

 

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Disha Ravi, a 21-year-old climate activist from Bengaluru, was arrested recently on charges of sedition for allegedly editing and sharing a social media document, or toolkit, about the ongoing farmer protest against the Farm Bills. She was later granted bail by a Delhi court which found no evidence of acts of sedition.

A number of politicians, activists, authors, journalists, and students have been arrested under the sedition law in the past in the country. And critics have been demanding the scrapping of the colonial-era law due to its repeated misuse. What is the sedition law all about?

What is sedition?

The Oxford Dictionary defines sedition as the use of words or actions that are intended to encourage people to oppose a government. An act is considered seditious when it incites people to rebel against the authority of a state, sometimes resorting to violence.

What is sedition law?

Section 124A of the Indian Penal Code lays down the rules of sedition law. It states sedition as an offence committed when "any person by words, either spoken or written, or by signs, or by visible representation, or otherwise, brings or attempts to bring into hatred or contempt or excites or attempts to excite disaffection towards the government established by law in India".

What is the punishment for sedition under the law?

Under Section 124A, sedition is a non-bailable offence, punishable with jail from three years to a life term. Besides, a person charged under this section is barred from a government job, deprived of a passport and required to appear in court as and when required.

When was the law introduced?

Section 124A of the Indian Penal Code (IPC) was introduced by the British Raj in 1870. In the 19th and early 20th centuries, during the British rule, the law was mainly used against freedom fighters, including Mahatma Gandhi, Bal Gangadhar Tilak, Annie Besant and Maulana Abul Kalam Azad. It was one of the many draconian laws enacted to stifle any voice of dissent at that time.

In 1962, the Supreme Court imposed limits on the use of the law, by making incitement to violence a necessary condition. (The British, which introduced the sedition law in India, abolished it in their country during the Gordon Brown Labour government in 2009, as the law was considered to be against freedom of expression.)

Why has there been a demand to scrap the sedition law in India?

Section 124A helps the government combat anti-national and terrorist elements. The law is essential to protect national integrity and the elected government from coup attempts (overthrow of an elected government through violent and illegal means).

The law becomes problematic only when its provisions are misused. Critics say the law is increasingly being exploited to silence criticism against the government. According to them, Section 124A is being used to stifle freedom of speech and expression of citizens and the colonial-era law goes against the essence of democracy because it is often used against people who question and criticise the policies of the government. Hence, there has been a growing demand to repeal the law. In fact, in 2018, the Law Commission of India published a consultation paper recommending that it is time to re-think or repeal Section 124A of the Indian Penal Code that deals with sedition.

How has the law been used in recent times?

According to the National Crime Records Bureau, between 2016 and 2019, the number of cases filed under Section 124A went up by 160%, while the rate of conviction dropped to 3.3% in 2019 from 33.39% in 2016. Some of the past cases are: in 2012 and 2013, about 23.000 people protesting against a nuclear power plant in Tamil Nadu were held for sedition. In 2014, 60 students in Kashmir were charged under Sec 124A for cheering the Pakistan cricket team.

In 2015, a singer was arrested for criticising the Tamil Nadu government's liquor policy in his songs.

In 2016, actor Divya Spandana was charged for praising the people of Pakistan.

Students who refused to stand up during the national anthem a man who clicked like on a Facebook post 1 Like Pakistan, and a number of people who took part in the anti-CAA and NRC protest were all charged with sedition.

 

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Neil Armstrong’s name will forever be enshrined in the annals of human spaceflight as the first person to land on the moon and walk on the lunar surface as space commander of the Apollo 11 mission of 1969. The Apollo 11 mission, however, wasn’t the first time Armstrong went to space. Armstrong was also part of the Gemini VIII mission that was equally eventful.

Bridging two programmes

The Gemini programme was conceived as a bridge between the Mercury and Apollo programmes. This meant that it was primarily to test equipment and various mission procedures while in Earth orbit and provide invaluable training experience for both astronauts and ground crews ahead of the Apollo missions. In that way, the Gemini VIII mission ticked a lot of boxes as it not only enabled another key spaceflight technology milestone for the U.S., but also tested the astronauts on-board and the ground crew involved with an in-flight problem, often quoted as the first emergency in space.

Gemini VIII’s crew consisted of American astronauts Neil Armstrong and David Scott. A member of the second group of NASA astronauts, Armstrong was a formal Naval aviator. Scott, who was the first member of the third group of astronauts to fly in space, was a U.S. Air Force pilot.

Complex countdown

With multiple counts running simultaneously involving both the Atlas Agena and Gemini Titan rockets and spacecraft on March 16, 1966, the countdown for the Gemini VIII mission was one of the most complex conducted till then. The countdown was successful as the Agena lifted off at 10 a.m. EST and the Gemini took off 101 minutes later.

As Gemini VIII’s primary mission was to perform rendezvous and four docking tests with the Agena target vehicle and to execute extravehicular activity (EVA), its orbital chase of Agena was on. Less than four hours into the mission, Armstrong and Scott had a solid radar lock with the Agena as they trailed it by 288 km. This was good news as it meant that the radar instruments onboard were working as expected.

“A real smoothie”

When they were 122 km away, they had a visual of the Agena. With Scott calling out radar range and closing rates, Armstrong judged the braking action by eye with the target in sight. Rendezvous was soon possible as Gemini achieved station-keeping with Agena at 150 feet.

Following a 35-minute fly around during which the astronauts took close-up looks of the Agena and deemed it safe to link up, they waited for the go-ahead from Mission Control. When they were cleared for docking, Armstrong achieved it and radioed back saying “It was a real smoothie.”

Not so smooth, after all

Shortly after docking, however, the Gemini capsule and target vehicle began tumbling. Armstrong used the Gemini’s orbital attitude and manoeuvring system (OAMS) to control the tumbling, but the rolling began immediately and Gemini VIII went out of range of ground communications.

While it was later confirmed on investigation that an OAMS thruster was firing erratically, probably due to short circuit in the wiring, the crew blamed the Agena as the scene was unfolding and hence went ahead and undocked. This, however, led to Gemini’s rate of spin accelerating quickly as the added mass of Agena was no longer there.

When Gemini VIII came in range of a tracking ship stationed southwest of Japan, Scott communicated that they were having serious problems. The astronauts’ vision became blurred by now as the spin rate approached one revolution per second. The tumbling had to be stopped.

Quick thinking

With some quick thinking, Armstrong turned off the entire OAMS and then used the re-entry control system (RCS) to regain control of the spacecraft and stop the spin. As Mission Control were aware that Armstrong had utilised 75% of the re-entry manoeuvring propellant to stop the spin, they too had to make some fast decisions. Mission rules dictated that the crew must be brought home once RCS was activated and the decision made stuck to those rules.

Ten hours and 41 minutes after liftoff, Gemini VIII’s splashdown occurred within 3.2 km of the predicted impact point. Once spotted in the water, three U.S. Air Force pararescuers jumped into the sea from an aircraft. They attached a floatation collar to the capsule and assisted Armstrong and Scott while waiting for pickup.

While the emergency meant that some of the mission objectives were forced to be abandoned, the primary target of docking with an uncrewed spacecraft had been achieved. The quick thinking and action of the crew and ground control ensured nothing untoward happened, meaning that there was more to be learnt and gained eventually.

Both Armstrong and Scott became heroes following this episode. Scott flew two more missions after Gemini VIII – Apollo 9 (first Earth orbital qualification test for Apollo spacecraft) and Apollo 15 (first extended scientific exploration of the moon). Armstrong, as you know, became the first person on the moon during the Apollo 11 mission.

 

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Stars all look the same colour, don’t they? That’s true if you see them with the naked eye. Through a telescope the picture changes. Once you look at stars when they are magnified, you see that they all have different colours.

Surface temperature controls the colour of a star. Our most familiar one is the sun. That has a surface temperature of around 5000  and is yellow-white in colour. There are plenty of stars in the universe far hotter than the sun. The hottest are twice as hot on the surface, and these are blue. Surprisingly, red stars are the coolest ones. The surface temperature on these is about 3000 . Knowing this, scientists are able to estimate the surface temperature of stars by carefully measuring their colours.

 

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Forest fires cause such terrible destruction that it seems impossible they can do anything but harm to a forest. In forests that are carefully maintained by foresters this may be true. Foresters thin the trees regularly. They clear away dead wood and brushwood that might slow the growth of trees. And they plant saplings to grow into future trees. A forest fire in one of these managed forests can be disastrous.

Out in the wild, things are different. There nature has to manage the forest by itself. Under these circumstances fire can be a great help. A forest fire burns up dead wood and brush-wood to clear the ground for new growth. It has also been discovered that certain trees only release their seeds at very high temperatures. In fact, these trees need to heat of a forest fire before they drop their seeds to start new trees growing.

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Mercury, closest to the Sun

Mercury is the nearest planet to the sun. It is a bare rocky ball covered with craters, much like our moon. Also like our moon, Mercury has broad, flat plains and steep cliffs.

Mercury spins and has day and night, but it spins very slowly. One day on Mercury takes 59 Earth days.

Mercury is very hot during the long day. Temperatures there reach higher than 400 °C. At night, temperatures take a big dip, sometimes to as low as -170 °C!

Mercury has a bigger temperature change than any other planet. This is because it is closest to the sun, and because it has very long days.

Mercury is a small planet. It could fit inside Earth two and one-half times. There are hardly any gases surrounding Mercury, so it has very little atmosphere.

Mercury is much closer to the sun than Earth is. So if you were standing on Mercury, the sun would appear much bigger and brighter.

Of course, you could not stand on Mercury in the middle of the day or night because it is either too hot or too cold. But scientists have explored it with a spacecraft that had no people on board.

The U.S. Mariner 10 was the first spacecraft to reach Mercury. Mariner 10 was a space probe. A space probe is a machine that explores space and sends information and pictures back to Earth. Astronauts do not travel in space probes. Scientists on Earth use computers to control space probes. On March 29, 1974, Mariner 10 flew within 740 kilometres of Mercury. It swept past the planet again on Sept. 24, 1974, and on March 16, 1975. During these flights, the probe took photographs of parts of Mercury’s surface. The U.S. space probe Messenger was launched in 2004 and began orbiting Mercury in 2011. Messenger became the first space probe to orbit Mercury. Messenger began to map the planet’s surface and study its magnetic field.

The Solar System

Our solar system contains the sun and the many objects that travel around it. Some are planets much larger than Earth. Others are tiny meteors and bits of dust.

The Sun’s Family

There are nine planets in our solar system. Each of them moves around the sun in a certain path. This path is called an orbit.

The first two planets, Mercury and Venus, are very close to the sun. The others are much further away. Two planets are much smaller than Earth. One is about the same size. And four are much bigger.

Like Earth and the moon, the other planets in our solar system reflect the sun’s light. That’s why we can see some of them at night.

The sun’s family also includes objects called asteroids, comets, dwarf planets, and meteoroids. Asteroids are small masses of rock or metal. Most of them move around the sun between the orbits of Mars and Jupiter.

Comets are frozen balls of ice, gas, and dust that travel around the sun. Comets have long shining tails.

Dwarf planets are small, nearly planet-sized objects that travel around the sun. Many dwarf planets are in the Kuiper belt, a region of space just beyond Neptune.

Meteoroids are chunks of rock or metal that move through space. When a meteoroid enters Earth’s atmosphere from outer space and begins to burn, it becomes a bright streak called a shooting star, or meteor.

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Moons of other planets

Earth is not the only planet that has a moon. Other planets do, too!

Mars has two little moons that are just lumpy chunks of rock. The largest of these, Phobos, is only about 27 kilometres wide. Mars’s other moon, Deimos, is about 15 kilometres wide.

Just how big are Mars’s moons? On a map, find the Cape Cod Canal, which separates Cape Cod from the rest of Massachusetts, U.S.A. The canal is 27 kilometres long. So Mars’s larger moon, Phobos, is as wide as the canal is long! Deimos is a little more than half that size.

Jupiter has at least 63 moons. A few of the smallest moons are smaller than some of the mountains on Earth. But the biggest, Ganymede, is bigger than the planet Mercury.

Saturn has at least 62 moons. Like Jupiter’s moons, Saturn’s are very different in size. Some are smaller than 10 kilometres in width. Saturn’s biggest moon, Titan, is bigger than Earth’s moon. Titan is also bigger than Mercury.

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High Tide, Low Tide

The regular rise and fall of the ocean is called the tide. The tide is caused mostly by forces of gravity from the moon. These forces produce two high tides and two low tides each day.

High tide takes place on the part of Earth that is nearest to the moon. At the same time, high tide also takes place on the part of Earth furthest from the moon.

This seems strange, but there are several reasons for tides. An important one is the way the moon’s gravity pulls on Earth.

On the side of Earth closer to the moon, the moon’s pull is slightly stronger than it is in the centre of Earth. On the opposite side of Earth, the moon’s pull is slightly weaker. High tide happens where the moon’s pull is strongest and also where it is weakest.

As Earth turns, the water sinks back down. After about six hours, this part of the sea is all the way down to what is called low tide.

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Life on the moon would be dark, quiet, and uncomfortable. But living there would definitely improve your high jump!

Earth’s sky looks blue during the day because the air on Earth scatters blue light from the sun in all directions. But there is no air on the moon to scatter sunlight, so its sky is pitch-black. On Earth, air carries sound. On the moon, no sound can be heard.

During the day, the moon’s surface gets hotter than boiling water. During the night, the moon is colder than the coldest place on Earth.

We are held on the surface of Earth by the pull of Earth’s gravity. When we weigh ourselves, we are really measuring how hard the gravity is tugging on us.

The moon’s gravity is weaker than Earth’s gravity. On the moon, you would weigh one-sixth as much as you weigh on Earth. If you weigh 27 kilograms on Earth, you would weigh only 4.5 kilograms on the moon! You could also jump six times higher on the moon than you could on Earth. And you could lift very heavy objects that you couldn’t even budge at home on Earth.

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The surface of the moon is not the same all over. In some areas, it has broad, flat plains covered with powdery rock dust. In other areas, it has rugged mountains. It also has billions of round holes in the ground called craters.

Some of the craters are no bigger than a pencil point. Some are the size of a car tyre. And some are really enormous. The biggest crater on the moon is over 1,000 kilometres across.

What formed the moon’s craters and mountains? Chunks of rock called meteoroids move around the sun, just as Earth and the moon do. Sometimes these meteoroids crash into the moon. The moon and the meteoroids are moving so fast that the meteoroids make craters in the moon’s surface when they crash.

When meteoroids strike, they usually form walls of rock around the craters they make. Many of the moon’s mountains are really walls made by meteors.

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An eclipse of the Moon

The night is clear, and a bright, full moon is shining. Slowly, a dark shadow begins to fall across the face of the moon. The shadow seems to move along until it completely covers the moon.

This event is called an eclipse of the moon, or a lunar eclipse. It takes place when Earth comes between the moon and the sun. The shadow creeping across the moon is the shadow of Earth!

What is Phases of the Moon? The moon seems to change from a thin crescent to a full circle. Each time the moon looks different, we say it is in a new phase. A phase is a change in the moon’s shape as it is seen from Earth.

1. In the moon’s first phase, it can’t be seen at all. That is because the moon is between Earth and the sun. The sun is shining on the side of the moon that faces the sun, but there is no sunlight on the side that faces us. So all we see is darkness.


2. After a day or two, the moon moves to one side of us. Then we can see a tiny bit of the side that is lit by the sun. We call this phase a crescent moon.


3. After about seven days, we can see half of the moon’s sunlit side. This phase is called a half moon.


4. After about two weeks, the moon is halfway around Earth from where it started. Now we can see the whole side of the moon that the sun is shining on. We call this phase a full moon. The moon keeps moving, and the part we can see gets smaller and smaller. Finally, the moon is between Earth and the sun again.

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The moon is made of cold, hard rock. It is not a ball of hot, glowing gas like the sun. Yet, somehow, the moon shines.

But the moon doesn’t give off its own light. It reflects light from the sun. That means light from the sun bounces off the surface of the moon and some of that light reaches us on Earth.

The moon does not really reflect sunlight very well. Most of the rock on the moon is rough and dark grey, not smooth and shiny like a mirror. But the sun’s light is so bright that even the tiny bit that is reflected from the moon makes the moon appears to be glowing.

Earth shines, too! It reflects some of the sunlight that falls on it.

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Myths about the Moon

Imagine that you lived in the world more than 2,000 years ago. Every night the moon appeared, but you had no idea what it was or why it seemed to change shape. Would you make up a story to explain it? Many ancient people did. Some early people thought the moon was a powerful god or goddess. The ancient Romans called their moon goddesses Luna and Diana. Diana was also the goddess of the hunt. The crescent moon was her bow, and the moonbeams were her arrow.

Some ancient people had stories about the moon and the sun together. Some Native Americans believed that the moon and the sun were brother and sister gods.

Some sky gazers saw figures like a cat, a frog, or a rabbit in the moon’s markings. Others saw the face of a man. Legends of various lands told how the “man in the moon” had been put in prison for stealing or for breaking religious rules.

Was there once life on the moon? Some people believed there was. A Greek writer named Plutarch told of moon demons that lived in caves. A German astronomer in the 1800’s, F. P. Gruithuisen, told of seeing a city on the moon through a telescope.

Even today, some people use stories to explain why the moon seems to change shape.

The San people of southern Africa tell one story that explains why the moon seems to change its shape. This story says that each month the moon almost dies. But it is reborn just in time to start life all over again. When this happens, it is seen as a thin sliver. For 13 nights, it grows until it becomes a full moon. The San celebrate this with three nights of dancing.

Then the moon begins to die again. For the next 13 nights, the sun, which the San see as the great hunter, battles the moon. Slowly the great hunter slices at the moon, until there is no moon left. For a few days, the moon seems to be dead. But soon it is reborn, and it begins growing again.

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The Moon

The moon is the brightest object in our night sky. On some nights, the moon looks like a huge shining circle of light. On other nights, it looks like a thin, silver fingernail. But the moon does not really change its size or shape. And it does not make its own light. The light we see comes from the sun and bounces off the moon.

The stars are trillions of kilometres away. The sun is millions of kilometres away. But the moon is only about 384,000 kilometres away. As Earth moves through space, the moon is always beside it. The moon moves around Earth.

The moon is smaller than most planets and stars. If Earth were the size of a basketball, the moon would be about the size of a tennis ball.

The moon is a ball of grey rock. Some of it is covered with dust. It has no air and no water. Most living things that we know of could not survive on the moon.

Long ago, many groups of people in different places worshipped the moon. The ancient Romans named the moon Luna. Our word lunar means “of the moon”.

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