Are Saturn's rings actually young?

The rings of Satum have fascinated and captivated humankind for over 400 years. It was in 1610 that Italian astronomer Galileo Galilei first observed these features through a telescope, though he had no idea what they were.

While our understanding of Saturn's rings has matured over these four centuries, the age of these rings haven't been determined precisely yet. The assumption that the rings likely formed at the same time as Satum draws flak as the rings are sparkling clean when compared to the planet.

A new study at the University of Colorado Boulder has provided the strongest evidence so far that the rings of Saturn are remarkably young. The research, published in May in the journal Science Advances, places the age of Saturn's rings at around 400 million years old. When we compare this with Saturn itself, which is 4.5 billion years old, the rings are really young.

Studying dust                                                                        

The researchers arrived at this number by studying dust. By studying how rapidly the layer of dust built up on Saturn's rings, they set out to put a date on it. It was, however, not an easy process.

The Cassini spacecraft provided an opportunity by arriving at Saturn in 2004 and collecting data until it intentionally crashed into the planet's atmosphere in 2017. The Cosmic Dust Analyzer, which was shaped a little bit like a bucket and was aboard this spacecraft, scooped up small particles as the spacecraft whizzed by.

Just 163 grains

The researchers were able to collect just 163 grains of dust that had originated from beyond Saturn's close neighbourhood during these 13 years. This quantity. however, was enough to make their calculations, placing the age of Saturn's rings at a little less than 400 million years.

With this, we now know approximately how old Saturn's rings are and that they are a relatively new phenomena in cosmic terms. With a previous study suggesting that Saturn's rings could entirely disappear in another 100 million years, questions pertaining to how these rings were initially formed and why these short-lived, dynamic rings can be seen just now still remain.

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Which is the smallest planet in the solar system?

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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Which is the largest planet?

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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What conditions could help more parts of Earth host life?

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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Is Earth the only planet that supports life?

Discovery about an Earth-like planet orbiting an M dwarf could imply that planets orbiting the most common star may be uninhabitable.

Is Earth the only planet that supports life? This is one of the many questions for which we don't have an answer yet. In a universe filled with countless stars and innumerable planets, our quest for life on a planet other than our own continues.

A new discovery could serve as a signpost and maybe even dramatically narrow our search for life on other planets. The discovery, explained in the Astrophysical Journal Letters in October by researchers from the University of California - Riverside, reveals that an Earth-like planet orbiting an M dwarf appears to have no atmosphere at all.

Most common type of star M dwarfs or red dwarfs are the most common type of star in the universe. This discovery could therefore imply that a large number of planets orbiting these stars may also lack atmospheres, and will therefore likely not support life.

The planet named GJ 1252b is slightly larger than our Earth, but is much closer to its star, an M dwarf, than the Earth is to the sun. On a single day on Earth, this planet orbits its star twice.

In order to find out if this planet lacks an atmosphere, astronomers measured infrared radiation from the planet as its light was during a secondary eclipse. In a secondary eclipse, the planet passes behind the star, and hence the planet's light along with the light reflected from its star are blocked.

Scorching temperatures

The radiation revealed the planet's daytime temperatures to be of the order of 2,242 degrees Fahrenheit. This, along with assumed low surface pressure, led the astronomers to believe that GJ 1252b lacks an atmosphere.

The researchers concluded that the planet will not be able to hold on to an atmosphere, even if it had tremendous amounts of carbon dioxide, which traps heat. Even if an atmosphere builds up initially, it would taper off and erode away eventually.

With M dwarf stars having more flares, the likelihood of planets surrounding them closely holding onto their atmospheres goes down further. The lack of atmosphere means that life as we know it is unlikely to flourish.

In Earth’s  solar neighbourhood, there are about 5,000 stars and most of them are M dwarfs. If planets surrounding them can be ruled -out entirely in the search for life based on this discovery, that would leave roughly around 1,000 stars similar to the sun that could be habitable.

For now, however, these can't be ruled out entirely. Nor can we rule out the possibility of a planet far enough away from an M dwarf star such that it retains its atmosphere. We need more research and results as we continue to embark on our search for life elsewhere.

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WHAT IS UV RADIATION?

Ultraviolet (UV) radiation is a form of electromagnetic radiation that comes from the sun. Humans have found use for this radiation in industry and dentistry. However, too much exposure to UV rays harms not just humans but can alter our environment because it can inhibit growth in green plants. The ozone layer that protects us from harmful UV rays has faced depletion, primarily due to certain types of chemicals we humans manufacture.

Our natural source of UV radiation:

The sun

Some artificial sources of UV radiation include:

  • Tanning beds
  • Mercury vapor lighting (often found in stadiums and school gyms)
  • Some halogen, fluorescent, and incandescent lights
  • Some types of lasers

UV radiation is classified into three primary types: ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC), based on their wavelengths. Almost all of the UV radiation that reaches earth is UVA though some UVB radiation reaches earth. UVA and UVB radiation can both affect health but UVA penetrates deeper into the skin and is more constant throughout the year.

Benefits

The production of vitamin D, a vitamin essential to human health.

Vitamin D helps the body absorb calcium and phosphorus from food and assists bone development. The World Health Organization (WHO) recommends 5 to 15 minutes of sun exposure 2 to 3 times a week.

Risks

Sunburn is a sign of short-term overexposure, while premature aging and skin cancer are side effects of prolonged UV exposure.
UV exposure increases the risk of potentially blinding eye diseases, if eye protection is not used.
Overexposure to UV radiation can lead to serious health issues, including cancer.

Skin cancer is the most common cancer in the United States. The two most common types of skin cancer are basal cell cancer and squamous cell cancer. Typically, they form on the head, face, neck, hands, and arms because these body parts are the most exposed to UV radiation. Most cases of melanoma, the deadliest kind of skin cancer, are caused by exposure to UV radiation.

Anyone can have harmful health effects from UV radiation, but the risks increase in people who:

Spend a lot of time in the sun or have been sunburned.
Have light-color skin, hair, and eyes.
Take some types of oral and topical medicines, such as antibiotics, birth control pills, and benzoyl peroxide products, as well as some cosmetics, may increase skin and eye sensitivity to UV in all skin types.
Have a family member with skin cancer.
Are over age 50.

To protect yourself from UV radiation:

Stay in the shade, especially during midday hours.
Wear clothes that cover your arms and legs.
Consider options to protect your children.
Wear a wide brim hat to shade your face, head, ears, and neck.
Wear wraparound sunglasses that block both UVA and UVB rays.
Use sunscreen with sun protection factor (SPF) 15 or higher, for both UVA and UVB protection.
Avoid indoor tanning. Indoor tanning is particularly dangerous for younger users; people who begin indoor tanning during adolescence or early adulthood have a higher risk of developing melanoma.

Credt : National centre for Environment health   

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WHAT IS SEA LEVEL RISE AND WHY IS IT HAPPENING?

As our planet warms, oceans across the globe absorb a large portion of the heat generated. In the process, the water expands, resulting in universal sea-level rise. In addition, the rise is also caused by the melting of glaciers and icebergs. Usually such melting during warmer months and freezing during colder months is a natural phenomenon. However, with global warming, there's more of the former than the latter, leading to alarming sea-level rise, threatening to submerge several cities within just a few decades.

Why does sea level change?

Causes sea level to rise because water expands as it warms up; melting of the world’s ice sheets. A large ice mass, which flows over hills and valleys and occupies a large portion of a continent. The world has only three major ice sheets today (Greenland, West Antarctica, and East Antarctica).

 In Greenland and Antarctica;  melting of smaller around the world; and decrease in the amount of water held on land, for example, in groundwater beneath the land and in reservoirs above the land. Ocean warming accounts for around half of the observed change in sea level (this is often called “thermal expansion”), with the melting of thousands of small glaciers accounting for the other half of the increase in sea level. Since the 1800s, the melting ice sheets in Antarctica and Greenland have contributed relatively little to sea level change. But, these ice sheets are starting to melt faster due to global warming and may push sea level up much more in the future.

How much could sea level rise?

Because of global warming, the thermal expansion of the ocean and glacier melting will continue to play a role in the rise of sea level in the future . If all of the planet’s remaining as small glaciers were to melt, sea level would rise about 50 cm. The amount that thermal expansion can raise sea level in the future will depend on the continued warming of sea water. The largest possible contribution to sea level rise in the future comes from the world’s large ice sheets in Greenland, West Antarctica, and East Antarctica. If these ice sheets melted completely, the level of the oceans would rise about 7 m from the Greenland ice sheet, 5 m from the West Antarctic ice sheet, and 53 m from the East Antarctic ice sheet. This is why many glaciologists (scientists who study ice) focus on how Greenland and Antarctica are changing because of global warming.

How will sea level rise affect the countries of the world?

The effect of ice sheet melting on sea level is different across the world.

So, when the sea level rises, people will be affected in different ways, depending on where they live. The UK is used to occasionally dealing with rising sea level for short periods of time, particularly when there are storms at the same time as when the tides higher than usual. If the IPCC predictions are correct, we must consider the possible increase in sea level on top of natural tidal surges. This will cause dangerously high tides to occur more often in the coming decades, and these future tides might be more destructive than we are used to.

In farming regions near the coast, seawater flooding on land can contaminate the soils with salt, making them less able to support the growth of crops. The salty water may also get into underground stores of fresh water (known as groundwater), which is the source of important drinking water and also for farmers to grow crops.

In coastal cities, sea level rise will cause more flooding to houses, businesses, and while it may seem sensible to consider moving cities away from harmful floods, especially as we know it will likely happen in the future, our cities cost so much to develop that we are more likely to simply try to protect them from rising sea levels. A vision of our cities near the sea involves them with walls facing the ocean several meters high, with the street level of the cities themselves being below the level of the ever rising sea.

Credit : Frontiers for young mind 

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WHAT IS PERMAFROST AND WHY IS IT IMPORTANT?

Permafrost is permanently frozen ground comprising soil, rocks, and sand, and often spans the Arctic regions. Found both on land and below the ocean floor, it covers vast expanses, and is a habitat for several animals and plants. Melting permafrost is a concern because it releases vast amounts of trapped greenhouse gases into the atmosphere.

What is Permafrost Made Of?

Permafrost is made of a combination of soil, rocks and sand that are held together by ice. The soil and ice in permafrost stay frozen all year long.

Near the surface, permafrost soils also contain large quantities of organic carbon—a material leftover from dead plants that couldn’t decompose, or rot away, due to the cold. Lower permafrost layers contain soils made mostly of minerals.

A layer of soil on top of permafrost does not stay frozen all year. This layer, called the active layer, thaws during the warm summer months and freezes again in the fall. In colder regions, the ground rarely thaws—even in the summer. There, the active layer is very thin—only 4 to 6 inches (10 to 15 centimeters). In warmer permafrost regions, the active layer can be several meters thick.

How Does Climate Change Affect Permafrost?

As Earth’s climate warms, the permafrost is thawing. That means the ice inside the permafrost melts, leaving behind water and soil.

Thawing permafrost can have dramatic impacts on our planet and the things living on it. For example:

  1. Many northern villages are built on permafrost. When permafrost is frozen, it’s harder than concrete. However, thawing permafrost can destroy houses, roads and other infrastructure.
  2. When permafrost is frozen, plant material in the soil—called organic carbon—can’t decompose, or rot away. As permafrost thaws, microbes begin decomposing this material. This process releases greenhouse gases like carbon dioxide and methane to the atmosphere.
  3. When permafrost thaws, so do ancient bacteria and viruses in the ice and soil. These newly-unfrozen microbes could make humans and animals very sick. Scientists have discovered microbes more than 400,000 years old in thawed permafrost.
  4. Because of these dangers, scientists are closely monitoring Earth’s permafrost. Scientists use satellite observations from space to look at large regions of permafrost that would be difficult to study from the ground.

Credit : Climate kids

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WHAT IS OZONE LAYER AND ITS IMPORTANCE?

About 15 to 35 km above the Earth's surface is gas called Ozone that surrounds the planet. This layer shields the Earth from the UV radiation from the sun However, pollution has caused this layer to thin exposing life on the planet to harmful radiation. The Montreal Protocol on Substances That Deplete the Ozone Layer (which was adopted on September 15, 1987) is an international treaty designed to protect the ozone layer from depletion by phasing out the production of a number of substances believed to be responsible for ozone depletion.

How is Ozone created?

When the sun's rays split oxygen molecules into single atoms, Ozone is created in the atmosphere. These single atoms combine with nearby oxygen to form a three-oxygen molecule — Ozone.

 Who discovered the Ozone Layer?

 The Ozone Layer was discovered by the French physicists Charles Fabry and Henri Buisson in 1913.

 Why is Ozone Layer important?

 Ozone protects the Earth from harmful ultraviolet (UV) rays from the Sun. Without the Ozone layer in the atmosphere, life on Earth would be very difficult. Plants cannot live and grow in heavy ultraviolet radiation, nor can the planktons that serve as food for most of the ocean life. With a weakening of the Ozone Layer shield, humans would be more susceptible to skin cancer, cataracts and impaired immune systems.

 Is Ozone harmful?

 Ozone can both protect and harm the Earth — it all depends on where it resides. For instance, if Ozone is present in the stratosphere of the atmosphere, it will act as a shield. However, if it is in the troposphere (about 10 km from the Earth's surface), Ozone is harmful. It is a pollutant that can cause damage to lung tissues and plants. Hence, an upset in the ozone balance can have serious consequences.

Disruption of Ozone Balance in the atmosphere

 Since the 1970s scientists have observed human activities to be disrupting the ozone balance. Production of chlorine-containing chemicals, such as chlorofluorocarbons (CFCs), have added to depletion of the Ozone Layer.

 What is 'Ozone Layer depletion'?

Chemicals containing chlorine and bromine atoms are released in the atmosphere through human activities. These chemicals combine with certain weather conditions to cause reactions in the Ozone Layer, leading to ozone molecules getting destroyed. Depletion of the Ozone Layer occurs globally, but the severe depletion of the Ozone Layer over the Antarctic is often referred to as the 'Ozone Hole'. Increased depletion has recently started occurring over the Arctic as well.

Credit : Business standard

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WHAT IS NITROGEN CYCLE? WHAT ARE THE STAGES OF NITROGEN CYCLE?

Our atmosphere is made up of 78% nitrogen. This element is essential for all living beings but we cannot directly take the nitrogen from the environment. We must absorb it through our food. The nitrogen cycle follows the circulation of nitrogen from the atmosphere to the soil, to animals and back. Nitrogen in the atmosphere falls to the earth through snow and rain. Once in the soil, the nitrogen combines with the hydrogen on the roots of the plants to form ammonia. This process is called Nitrogen fixation. Additional bacteria further combine this ammonia with oxygen in a process called Nitrification. At this point, the nitrogen is in a form called nitrite, which is further converted into nitrate by the bacteria. Plants can absorb nitrogen in this state through a process called assimilation and the rest is utilised by the bacteria. The remainder is released back into the atmosphere through the process of denitrification.

Nitrogen Cycle Explained – Stages of Nitrogen Cycle

Process of the Nitrogen Cycle consists of the following steps – Nitrogen fixation, Nitrification, Assimilation, Ammonification and Denitrification. These processes take place in several stages and are explained below:

Nitrogen Fixation Process

It is the initial step of the nitrogen cycle. Here, Atmospheric nitrogen (N2) which is primarily available in an inert form, is converted into the usable form -ammonia (NH3).

During the process of Nitrogen fixation, the inert form of nitrogen gas is deposited into soils from the atmosphere and surface waters, mainly through precipitation.

The entire process of Nitrogen fixation is completed by symbiotic bacteria, which are known as Diazotrophs. Azotobacter and Rhizobium also have a major role in this process. These bacteria consist of a nitrogenase enzyme, which has the capability to combine gaseous nitrogen with hydrogen to form ammonia.

Nitrogen fixation can occur either by atmospheric fixation- which involves lightening, or industrial fixation by manufacturing ammonia under high temperature and pressure conditions. This can also be fixed through man-made processes, primarily industrial processes that create ammonia and nitrogen-rich fertilisers.

Assimilation

Primary producers – plants take in the nitrogen compounds from the soil with the help of their roots, which are available in the form of ammonia, nitrite ions, nitrate ions or ammonium ions and are used in the formation of the plant and animal proteins. This way, it enters the food web when the primary consumers eat the plants.

Ammonification

When plants or animals die, the nitrogen present in the organic matter is released back into the soil. The decomposers, namely bacteria or fungi present in the soil, convert the organic matter back into ammonium. This process of decomposition produces ammonia, which is further used for other biological processes.

Denitrification

Denitrification is the process in which the nitrogen compounds make their way back into the atmosphere by converting nitrate (NO3-)  into gaseous nitrogen (N). This process of the nitrogen cycle is the final stage and occurs in the absence of oxygen. Denitrification is carried out by the denitrifying bacterial species- Clostridium and Pseudomonas, which will process nitrate to gain oxygen and gives out free nitrogen gas as a byproduct.

Conclusion

Nitrogen is abundant in the atmosphere, but it is unusable to plants or animals unless it is converted into nitrogen compounds.

Nitrogen-fixing bacteria play a crucial role in fixing atmospheric nitrogen into nitrogen compounds that can be used by plants.

The plants absorb the usable nitrogen compounds from the soil through their roots. Then, these nitrogen compounds are used for the production of proteins and other compounds in the plant cell.

Animals assimilate nitrogen by consuming these plants or other animals that contain nitrogen. Humans consume proteins from these plants and animals. The nitrogen then assimilates into our body system.

During the final stages of the nitrogen cycle, bacteria and fungi help decompose organic matter, where the nitrogenous compounds get dissolved into the soil which is again used by the plants.

Some bacteria then convert these nitrogenous compounds in the soil and turn it into nitrogen gas. Eventually, it goes back to the atmosphere.

These sets of processes repeat continuously and thus maintain the percentage of nitrogen in the atmosphere.

Credit : BYJU’S 

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WHAT ARE MANGROVES?

Mangroves are bushes or trees that grow in thick clusters along sea coasts and riverbanks.

Their roots stick out of the mud in thick tangles and prevent the waves from washing away the sand (or dirt) from the coastline Sundarbans in Bangladesh and India is the world's largest single tract of mangroves.

Where Are Mangroves Found?

Mangroves grow in sheltered tropical and subtropical coastal areas across the globe. In general, this is an area between latitudes of 25 degrees north and 25 degrees south, however, geographical limits are highly variable depending upon the area of the world and local climates. In Eastern Australia, the mangrove Avicennia marina can grow as far south as 38 degrees and Avicennia germinans can grow as far north as 32 degrees in the Atlantic. A major restriction for where mangroves can live is temperature. The cooler temperatures of northern temperate regions prove too much for the mangroves. A fluctuation of ten degrees in a short period of time is enough stress to damage the plant and freezing temperatures for even a few hours can kill some mangrove species. However, rising temperatures and sea level due to climate change are allowing mangroves to expand their ranges farther away from the equator and encroach on temperate wetlands, like salt marshes. Also, on some isolated tropical islands, such as Hawaii and Tahiti, mangroves are not native and are sometimes considered invasive species.

Growth and Reproduction

Life by the ocean has its perks—for mangroves, proximity to the waves and tides helps with reproduction. 

For most plants, the seeds remain dormant until after they are dispersed to a favorable environment. Not mangroves. Mangrove offspring begin to grow while still attached to their parent. This type of plant reproduction is called vivipary. After mangrove flowers are pollinated the plants produce seeds that immediately begin to germinate into seedlings. The little seedlings, called propagules, then fall off the tree, and can be swept away by the ocean current. Depending upon the species, propagules will float for a number of days before becoming waterlogged and sinking to the muddy bottom, where they lodge in the soil. Propagules of Rhizophora are able to grow over a year after they are released from their parent tree, while the white mangrove, Laguncularia racemosa, floats for up to 24 days, though it starts losing its ability to take root after eight. The flotation time allows for the propagules to vacate the area where their parent grows and avoid competition with an already established mangrove.

Mangroves as Ecosystems

Mangroves are among the most productive and biologically complex ecosystems on Earth. They cover between roughly 53,000 and 77,000 square miles (138,000 and 200,000 square km) globally, acting as a bridge connecting the land and sea. Though most will be less than a couple miles thick along the coastline, in some areas of the world they are massive aquatic forests. The Sundarbans Forest, a UNESCO World Heritage site at the mouth of the Ganges, Brahmaputra, and Megha Rivers in the Bay of Bengal fronting India and Bangladesh, is a network of muddy islands and waterways that extends roughly 3,860 square miles (10,000 square km), two times the size of the state of Delaware. 

Credit : Ocean find your blues

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WHAT ARE KEYSTONE SPECIES?

Keystone species play a unique and crucial role in the functioning of an ecosystem. The animals and organisms that come under this category help to maintain biodiversity within their community either by controlling populations of other species that would otherwise dominate the community or by providing critical resources for the survival of a wide range of organisms.

These species act as the glue that holds the system together. The term was coined by Dr Robert Paine in 1969, to describe the power a single species exerts on an ecosystem. Examples of keystone species include starfish, sea otters, beavers, wolves, elephants, prairiedogs and bees.

Keystone Species Examples

Sea Otter

The sea otter (shown below) is considered a keystone species as their consumption of sea urchins, preventing the destruction of kelp forests caused by the sea urchin population. Kelp forests are a critical habitat for many species in nearshore ecosystems. In the absence of sea otters, sea urchins feed on the nearshore kelp forests, thereby disrupting these nearshore ecosystems. However, when sea otters are present, their consumption of sea urchins restricts the sea urchin population to smaller organisms confined to protective crevices. Thus, the sea otter protects the kelp forests by reducing the local sea urchin population.

Large Mammalian Predators

While small predators are important keystone species in many ecosystems, as mentioned above, large mammalian predators are also considered keystone species in larger ecosystems. For example, the lion, jaguar (shown below), and gray wolf are considered keystone species as they help balance large ecosystems (e.g., Central and South American rainforests) by consuming a wide variety of prey species.

Sea Star

Sea stars (shown below) are another commonly recognized keystone species as they consume mussels in areas without natural predators. In many cases, when the sea star is removed from an ecosystem, the population of mussels proliferates uncontrollably, and negatively effects the resources available to other species within the ecosystem.

Credit :  Biology dictionary  

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WHAT IS THE JET STREAM?

Jet streams are bands of strong wind that generally blow from the west to the east across the world. They impact weather, air travel and many other things that take place in our atmosphere. They form when warm air masses meet cold air masses in the atmosphere. The fast-moving air currents in a jet stream can impact the weather system in a region affecting temperature and precipitation. But if a weather system is far away from a jet stream, it might hover over one place, causing heat waves or floods.

What Causes Jet Streams?

Jet streams form when warm air masses meet cold air masses in the atmosphere.

The Sun doesn’t heat the whole Earth evenly. That’s why areas near the equator are hot and areas near the poles are cold.

So when Earth’s warmer air masses meet cooler air masses, the warmer air rises up higher in the atmosphere while cooler air sinks down to replace the warm air. This movement creates an air current, or wind. A jet stream is a type of air current that forms high in the atmosphere.

On average, jet streams move at about 110 miles per hour. But dramatic temperature differences between the warm and cool air masses can cause jet streams to move at much higher speeds — 250 miles per hour or faster. Speeds this high usually happen in polar jet streams in the winter time.

How Do Jet Streams Affect Air Travel?

Jet streams are located about five to nine miles above Earth’s surface in the mid to upper troposphere — the layer of Earth’s atmosphere where we live and breathe.

Airplanes also fly in the mid to upper troposphere. So, if an airplane flies in a powerful jet stream and they are traveling in the same direction, the airplane can get a boost. That’s why an airplane flying a route from west to east can generally make the trip faster than an airplane traveling the same route east to west.

How Do Jet Streams Affect Weather?

The fast-moving air currents in a jet stream can transport weather systems across the United States, affecting temperature and precipitation. However, if a weather system is far away from a jet stream, it might stay in one place, causing heat waves or floods.

Earth’s four primary jet streams only travel from west to east. Jet streams typically move storms and other weather systems from west to east. However, jet streams can move in different ways, creating bulges of winds to the north and south.

How Does the Jet Stream Help Us Predict the Weather?

Weather satellites, such as the Geostationary Operational Environmental Satellites-R Series (GOES-R), use infrared radiation to detect water vapor in the atmosphere. With this technology, meteorologists can detect the location of the jet streams.

Monitoring jet streams can help meteorologists determine where weather systems will move next. But jet streams are also a bit unpredictable. Their paths can change, taking storms in unexpected directions. So satellites like GOES-16 can give up-to-the-minute reports on where those jet streams are in the atmosphere — and where weather systems might be moving next.

Credit : Science jinks 

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WHAT IS INFRARED RADIATION?

Infrared radiation or infrared light is a radiant energy that is invisible to the human eyes, but can be felt as heat. It is a type of electromagnetic radiation spectrum with frequencies being produced when atoms absorb and release energy. The two most obvious sources of infrared light are the sun and fire.

Every object in the universe can emit IR radiation at some level and the most well-known sources are fire and the sun.

IR is a kind of electromagnetic radiation wherein frequencies in a continuum get produced as atoms that release and absorb energy.

It can go from the lowest to the highest frequency.

Included in electromagnetic radiation are radio waves, microwaves, infrared radiation, gamma rays, X-rays, visible light, and ultraviolet radiation.

When these kinds of radiation go together, they create the electromagnetic spectrum.

According to NASA, William Herschel, a well-known British astronomer, discovered infrared light in the year 1800.

He had an experiment that could measure how the colors in the visible spectrum have different temperatures.

He had thermometers placed in the light path of every color in the visible spectrum and was able to observe the temperature increase when it went from blue to red.

William also discovered that the measurement of warmer temperature was beyond the visible spectrum’s red end.

Infrared waves happen at frequencies above the microwaves in the electromagnetic spectrum.

They are just below the visible red light, which is why they are called “infrared.”

As per Caltech or the California Institute of Technology, compared to visible light, infrared radiation has longer waves.

The IR frequencies can range from around 300 GHz to approximately 400 THz, with wavelengths estimated to have a range from 1,000 micrometers to 760 nanometers.

However, according to NASA, these values may not be definitive.

Just like the visible spectrum of light that ranges from the longest wavelength of red to the shortest visible light wavelength of violet, infrared radiation comes with a range of wavelengths of its own.

According to NASA, the “far-infrared” waves are longer and closer to the electromagnetic spectrum’s microwave section.

You can feel this as intense heat that is the same as the heat from fire or sunlight.

“Near-infrared” waves that are shorter can be closer to the electromagnetic spectrum’s visible light.

Aside from that, it does not emit detectable heat like what the television’s remote control discharges whenever it changes the channels.

One of the ways you can have heat transferred between two places is IR radiation.

Conduction and convection are the other two.

Everything that has a temperature of more than -268°C or -450°F can emit IR radiation.

As per the University of Tennessee, half of the sun’s total energy is emitted as IR and most of the visible light of a star can get re-emitted and absorbed as IR.

Credit : IRDA

Picture Credit : Google 

WHAT IS HOLOCENE EPOCH?

The Holocene Epoch is the current period of geologic time. It relates to the global changes caused by human activity, and is said to have begun about 11.700 years ago after the icy Pleistocene ended. When the glaciers of the ice era retreated, Earth entered a period of warming. The landscape of the tundra changed, large mammals that had adapted to the extreme cold became extinct, and humans who hunted the mammoth mammals began exploring plant materials to supplement their diet. Climatic changes took place, the human population began to grow, and sadly, we began ushering in processes and inventions that would have serious implications on the future of the planet.

The classification of the geological time scale is done into the following: Eons, Eras, Periods, Epochs and Ages. In this timeline classification, Eons are divided into Eras, Eras are further divided into Periods, Periods divided into Epochs and the Epochs are further subdivided into Ages. Thus, Holocene is an Epoch classified under the Quaternary Period, which comes under the Cenozoic Era, which is classified under the Phanerozoic Eon.

Under the classification of the Quaternary Period, comes the Pleistocene Epoch and Holocene Epoch. The Holocene is the Epoch which follows the Plestocene Epoch. It is also identified as a warm period and an interglacial period by the geologists, and Earth scientists. The striking feature of the Holocene time scale is the rapid proliferation, growth, and the impacts of Human species. The Holocene is characterized by all of the written history, technological advancements, development of many civilizations, and the current transition towards urbanization of the human population. The influence of humans is predominant in this Epoch and the impact on modern-era Earth and the ecosystems have led to the classification of the Holocene. 

The Holocene Time-scale

The word Holocene finds its origin in the Ancient Greek language. Holocene meaning, according to Ancient Greek, is “whole new”. Breaking the word of Holocene into the Greek roots helps in identifying the holocene meaning. The term ‘Holo-’ is derived from the word Holos which means “whole”. The other ‘-cene’ is derived from the word kainos which means “new”.Thus, when combined together, the holocene meaning is “whole new”. The reasoning behind this, is the consideration that this epoch is entirely new as it is the most recent one and is still continuing. Also, the suffix ‘-cene’ is used for all the seven epochs that are classified under the Cenozoic Era. 

According to the International Commision on Stratigraphy, the Holocene started 11,650 calibrated years ago before present. The Holocene Epoch is further sub-divided into five time intervals based on climatic fluctuations, which are also known as the Chronozones:

Preboreal: This is the time period between 10 kiloannum (ka) years - 9 ka before present (BP) (present i.e. 195)). 
Boreal: This lies between 9 ka - 8 ka years BP
Atlantic: 8 ka to 5 ka years BP
Subboreal: 5 ka - 2.5 ka years BP
Subatlantic: 2.5 ka years BP.

During the time of the Holocene, there have been many changes that have taken place in terms of geology and climate which have shaped the current world. Also, the changes occurring due to Global warming in the last century itself has also impacted the natural progression of this Epoch. We will understand a few of these changes as we go through with the article.

Geological Changes During Holocene

The movements of the continent under the pressure of tectonic forces, has been less than a kilometre in the span of 10,000 years of Holocene. Another important change in the geology of the Earth, during this Epoch has been the rise in the sea-level. In the early part of the Holocene Epoch, because of the melting of ice, the sea-level rises about 35 m. In the later part of the Epoch also, the sea-level rises by another 30 m. Many of the areas of landmass above around 40 degrees North latitude that had been covered by ice of the Pleistocene Epoch were depressed by the weight of Ice. Hence, as the glacial period began to recede and the ice began to melt, the landmass rose by180 meters during the late Pleistocene and early Holocene Epoch. These landmasses still continue to rise. 

Climate Changes During Holocene

As such the climate changes have been stable over the Holocene when compared to the cold period of Glaciation. The records collected from the ice cores have shown that before the start of Holocene there was a time period of warming happening globally which began after the end of the last of the ice ages and the cooling periods. The climatic changes became more and more regional and during the transition from the late glacial to Holocene the cold reversal known as Huelmo-Mascardi, began from South America in the Southern Hemisphere and most of the warmth flowed from south to north about 11,000 to 7,000 years ago. It is thought that this happened because of the residual glacial ice which was left in the Northern Hemisphere.

Early Human Settlements During Holocene

The Mesolithic age began with the beginning of the Holocene in most of Europe. In the regions of Middle East and Anatolia a very early neolithisation and Epipaleolithic period began. During this period the cultures that began include Hamburgian, Federmesser and Natufian culture. Also, some of the oldest inhabited places that are still existing such as the Tell es-Sultan (Jericho) in the Middle East began to be first settled. Other evidence of such settlements are given by archaeology at locations of Göbekli Tepe where proto-religion first began as long as 9th millennium BCE. Since then human courses have taken the known developments and continue till date.

It is noteworthy that, using terms like Holocene period, Holocene era or Holocene age, can be confusing as the terms period, era and age have different and definite meaning under the Geographical Time Scale classification system Hence, using Holocene or Holocene Epoch is more reliable and justifiable under such circumstances. 

Credit : Vedantu learn live 

Picture Credit : Google