My Science School

NASA's James Webb Space Telescope (JWST) is an infrared space observatory that launched on Dec 25, 2021, from ESA's launch site at Kourou in French Guiana, at 7:20 a.m. EST (1220 GMT; 9:20 a.m. local time in Kourou), aboard an Arianespace Ariane 5 rocket. 

NASA released the first scientific images from Webb at a live event on July, 12. Explore the first images in more detail and what it means for JWST science in our recently published article.

The $10 billion James Webb Space Telescope — NASA's largest and most powerful space science telescope — will probe the cosmos to uncover the history of the universe from the Big Bang to alien planet formation and beyond. It is one of NASA's Great Observatories, huge space instruments that include the likes of the Hubble Space Telescope to peer deep into the cosmos.

The release of the first full-colour images and spectroscopic data will mark the beginning of the next era in astronomy as Webb will help answer questions about the earliest moments of the universe and allow astronomers to study exoplanets in greater detail than ever before. James Webb was launched in December to succeed the revolutionary - but now ageing-Hubble Space Telescope. The James Webb Space Telescope uses a 19.7-foot-tall primary mirror to collect light. That light is bounced to a smaller secondary mirror, which then redirects it onto the telescope's instruments, including a camera that records an image.

While Hubble looks mostly in the visual and ultraviolet parts of the electromagnetic spectrum, Webb will look at longer wavelengths in the infrared, to see what the universe looked like around 100 to 250 million years after the Big Bang, when the first stars and galaxies were formed.

Early alignment imagery already demonstrated the unprecedented sharpness of Webb's infrared view. However, these new images will be the first in full colour and the first to showcase Webb's full science capabilities.

Credit : Space.com 

Picture Credit : Google 

Researchers from Weizmann Institute of Science have developed an advanced, innovative method to detect non-visual traces of fire. Using this method, they have discovered one of the earliest known pieces of evidence for the use of fire, dating back at least 8,00,000 years. Their results have been published in an article late in June in PNAS.

Ancient hominins are a group that includes humans and some of our extinct family members. The controlled use of fire by this group dates back at least a million years. Archaeologists believe that this was the time when Homo habilis began its transition to Homo erectus.

Cooking hypothesis

A working theory called the "cooking hypothesis", in fact, postulates that the use of fire was instrumental in our evolution. Controlled fire not only allowed for staying warm, crafting tools, and warning off predators, but also enabled cooking, paving the way for the growth of the brain.

Traditional archaeological evidence relying on visual identification of modifications resulting from combustion has provided widespread evidence of fire use no older than 2,00,000 years. Sparse evidence of fire dating back to 5,00,000 also exists.

The team of scientists involved in this research had pioneered the application of Al and spectroscopy in archaeology to find indications of controlled burning of stone tools. For this research, they developed a more advanced Al model capable of finding hidden patterns across a multitude of scales. Output of the model could thus estimate the temperature to which the stone tools were heated.. providing insights into past human behaviours.

Assess heat exposure

The researchers took their method to Evron Quarry, an open-air archaeological site first discovered in the 1970s. The site is home to fossils and tools dating back to between 8,00,000 and 1 million years ago, but without any visual evidence of heat. With their accurate Al, the team assessed the heat exposure of 26 flint tools. The results showed that these tools had been subjected to a wide range of temperatures, with some even being heated to over 600 degree Celsius. The presence of hidden heat puts the traces of controlled fire to at least 8,00,000 years ago.

Apart from identifying non-visual evidence of fire use, the scientists hope that their newly developed technique will provide a push toward a more scientific, data-driven archaeology that uses new tools. The researchers believe that this will help us understand the behaviour of our early ancestors and the origins of the human story.

Picture Credit : Google 

While the livelihoods of more than three billion people depend on oceanic resources, the ocean also provides a large fraction of the oxygen we breathe and absorbs greenhouse gases, mitigating their effects in the atmosphere. Playing a key role in the Earth’s climate and weather systems, as well as in the global carbon cycle, the ocean is an immeasurable force of nature. However, human activities have fundamentally altered the ocean’s chemical composition. Since the late 1980s, 95 per cent of open ocean surface water has become more acidic. Oceans absorb about 30 per cent of carbon dioxide (CO2) we produce, reducing the pH of seawater. This process is known as ocean acidification. With atmospheric CO2 levels 50 per cent above pre-industrial levels, the problem is getting worse.

What is pH and acidity?

pH is the measure of the acidity or basicity of a liquid solution. A solution’s pH represents the concentration of hydrogen ions (H+) and hydroxyl ions (OH-) on a scale of 0 to 14. Pure water has a pH of 7 and is neutral – neither acidic nor basic – with equal concentrations of H+ and OH?. A solution with a pH lower than 7 is acidic, while a solution with a pH greater than 7 is basic. The pH scale is logarithmic, so a decrease of one pH unit is a ten-fold increase in acidity.

The ocean is slightly basic. Prior to the Industrial Revolution of the 18th to 19th centuries, the ocean’s average pH was about 8.2. Today, the ocean’s average pH is 8.1. This means that the ocean today is about 30 per cent more acidic then in pre-industrial times. By 2100, the pH of the ocean could decrease to about 7.8, making the ocean 150 percent more acidic and affecting half of all marine life, according to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report.

What is the effect of a more acidic ocean?

Ocean acidification threatens marine ecosystems, which also affects populations who rely on the ocean as a source of income and diet. Over three billion people depend on marine and coastal biodiversity for their livelihoods.

For marine ecosystems, ocean acidification presents a two-fold challenge: higher acidity and lower availability of carbonate ions (CO32-). Calcifying organisms – such as oysters, crabs, sea urchins, lobsters and coral – need CO32- to build and maintain their shells and skeletons. Furthermore, studies suggest marine shells and skeletons may dissolve more easily as pH decreases. Scientists are studying the extent to which calcifying organisms are affected by acidification and how some organisms may be more sensitive than others.

Energy spent by marine organisms overcoming more acidic conditions may reduce the energy available for physiological processes, such as reproduction and growth, threatening the stability of food chains that would affect the ecosystem resilience and economic activities, such as fisheries and tourism.

Credit : International atomic energy agency

Picture Credit : Google 

 

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

Picture Credit : Google 

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 

Picture Credit : Google