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Researchers develop images to understand how Earth might look to aliens

In the last ten years, 4000 exoplanets which we currently know were discovered. In this period, the process shifted gradually from discovery to characterisation. In the future, advanced equipments will help to know more about the surfaces and atmospheres of exoplanets. 

Scientists raised a question about what an advanced species would see while studying the planet. Researchers from Caltech constructed a map of what Earth would appear to alien observers with the help of Earth’s multi-wavelength data. It would also serve in studying about the surface features of exoplanets similar to Earth in the future. 

The study titled “Earth as an Exoplanet: A Two-dimensional Alien Map” appeared in Science Mag journal. It is led by Siteng Fan and several scientists from Division of Geological and Planetary Sciences, California Institute of Technology and Jet Propulsion Laboratory of NASA.

2d surface map of earth

A 2D surface map of the Earth treated as a proxy exoplanet. S Fan et al/California Institute of Technology/arXiv

For finding potentially habitable planets out of Solar System, scientists cannot observe the exoplanets directly, to understand their atmosphere and surface features. So they have to only work with the indications which show that a planet is similar to Earth. 

Fan said that the present exoplanet studies have not set the minimum requirements for habitability. Researchers are not sure about whether the proposed criteria are either sufficient or necessary. Besides this, the observation techniques are not enough to confirm the habitability. 

As right now we know that life exists only on Earth, scientists theorized that remotely observing our planet might act as a proxy for what a habitable exoplanet might look like to an alien civilisation. The water cycle is one of the major elements of the climate on Earth and it consists of three phases. They are water vapour in the atmosphere, clouds consisting of condensed water and water bodies on the surface of Earth.

So their presence might be considered as indications of life and habitability which could be detected from a distance. To obtain Earth’s view to foreign observers, researchers compiled 9740 images that were taken every 68 to 110 minutes in 2016 and 2017 by Deep Space Climate Observatory of NASA. They were able to capture the light reflected from the atmosphere of Earth at different wavelengths. 

Images were then combined to create a 10-point reflection spectrum plotted against time, integrated over Earth’s surface. This created what Earth might look like to someone who observed Earth from several light years away for a period of two years. 

Fan said that the second principal component of the light curve of Earth is related to the fraction of land of the illuminated hemisphere. The reconstruction of the map translated to a problem of linear regression. So the team found the curve parameters for land and clouds after analysis of the resulting curves and comparing with the original images. They identified those parameters related to the land and adjusted it to Earth’s rotation which generated a contour map.

Black lines represent the surface feature and correspond to the coastlines of the continents which are coloured in green to roughly represent the continents. Red denotes the shallow sections of the ocean with blue depicting the deeper areas. These representations would help the scientists to understand if an exoplanet contained oceans, ice caps and clouds. Variation of life curve is dominated by clouds, land and oceans which are important for life on Earth. 

In the future, instruments such as James Webb Space Telescope would help in carrying out detailed exoplanet surveys. Ground-based instruments such as Extremely Large Telescope, Thirty Meter Telescope would carry out direct imaging of planets that orbit close to their stars. With all these advancements, researchers would be able to properly determine which exoplanets are habitable and soon find the next Earth. 

Journal Reference: Science Mag

Scyliorhinus canicula

Researchers identify previously unknown mechanism through which sharks produce eerie glow

Unlike other creature, glowing catsharks that are present in the saline depths have a fluorescence mechanism that could be conferring some serious perks – such as the ability to pick out other sharks among the many fluorescent things on the seafloor

Biologist David Gruber of the City University of New York said that after they first reported that swell sharks were bio fluorescent, he along with his collaborators decided to plunge deeper into the topic learning more about bio fluorescence and its meaning which is constantly evolving mystery. The study has been published in iScience.

Evolution is a funny thing. Animals that are very different from one another can end up doing the same cool tricks. This phenomenon is called parallel evolution, and it can be fascinating to observe.

Biofluorescence, as an example, is a phenomenon in which living organisms like frogs, scorpions, chameleons, turtles, and a whole plethora of sea creatures can absorb and re-emit light in a different colour which is not to be confused with bioluminescence in which organisms glow with the light they produce themselves.

Majority of animals fluoresce by producing a green fluorescent protein (GFP), proteins that are very similar to GFP, or fatty acid-binding proteins (FABP). But the biofluorescent glow produced by a different chemical pathway is seen only in the two species of catshark – The Chain Catshark (Scyliorhinus retifer) and the Swell Shark (Cephaloscyllium ventriosum) both of which are flecked with light and dark patterns.

The sharks’ glow is produced by brominated tryptophan-kynurenine small-molecule metabolites, found only in the lighter parts of patterned skin while it is involved in the immune system and the central nervous system in other vertebrates. The metabolites in the shark’s skin help produce fluorescence in low-light conditions on the seafloor.

This is invisible to the human eye but the sharks’ eyes can see it, that’s why fluorescence wasn’t discovered until 2014. They channel that fluorescence through their scales, or denticles specifically structured for the task, so that they gleam with the re-emitted green light.

Researchers think that as it’s a different chemical pathway from those used by other sea animals, it might be a secret visual language which only shark understand. Chemical biologist Jason Crawford of Yale University said that because of these biofluorescent characteristics that their skin shows and that their eyes can detect, they have a completely different view of the world and to see each other which no other animal can link to.

Researchers want to determine the role of metabolites in keeping the sharks clean. Both the species of catshark spend a lot of time in the sediment, which contains more bacteria than the water column and having anti-fouling properties. Staphylococcus aureus and Vibrio parahaemolyticus, the two bacterial pathogens when pitted against isolated metabolites, two of the metabolites showed some ability to inhibit the growth of these bacteria showing antimicrobial properties.

Gruber said that sharks have been fascinating creatures for over 400 million years and the study highlights yet another mystery of sharks and inspires us to learn more about their secrets and work to better protect them.

Journal Reference: iScience

These Tiny, Weird Worms Make One of The Loudest Sounds Ever Recorded in The Ocean

Researchers detect tiny worm making one of the loudest sounds ever recorded in ocean

We generally imagine that very loud sounds are usually generated by screams or booms which make the entire body vibrate. It is not always that we guess an abrupt pop from a marine worm can produce a sound of such intensity. It has been observed that a tiny 29-millimeter marine worm makes one of the loudest sounds ever recorded in the ocean. The worm species is named Leocratides kimuraorum.

Marine biologist Ryutaro Goto from Kyoto University and his colleagues measured the sounds made by these polychaete worms to be around 157 decibels. The human ear can hear sounds as low as 10 decibels but the sound above 130 decibels can be painful and damaging for our ears. The study has been published in the journal Current Biology.

Several aquatic creatures including fishes, mammals, and insects produce very loud sounds underwater. It is highly unlikely for a soft-bodied worm to produce a loud snap because brief, intense sounds of such nature usually need quite extreme movements and very sophisticated energy storage mechanisms in their body.

Goto and his fellow colleagues were surprised by the racket this creature can create and also initially thought that these creatures were silent. The researchers thought that these soft-bodied animals were not known to produce large sounds until the team took these polychaetes into the lab and witnessed the popping noises which they were able to generate with their mouth. Scientists predict that the loud pop may be a byproduct of the rapid mouth attack but it can also be an aid for the interspecific communication between the species.

These worms produce this loud noise by opening their thick pharyngeal muscles which in turn further create a cavity bubble before exploding it open forcefully. These worms stake out holes in the sea sponges along the Pacific coast of Japan where they wait for the prey to attack and fiercely defend their area from the rivals. Thus this biomechanical puzzle hints at a different sort of extreme biology and making it very clear that marine invertebrates having soft bodies can also generate very loud sounds underwater.

Journal: https://www.sciencedirect.com/science/article/abs/pii/S0960982219306177

pluto new horizon

Researchers discover Pluto to have oceans, otherwise considered fully frozen

Pluto, the ninth planet in our solar system has always been a planet of interest to many scholars and scientists. The existence of Pluto as a planet was a topic of debate in the higher circles of the researchers. Clyde Tombaugh discovered Pluto in 1930 and it was originally considered to be the ninth planet in our solar system. It was declared a heavenly body and not a planet due to its small size compared to others.

It was thought that the temperature required to maintain a liquid temperature on Pluto was too high but the thick ice has not melted. A new breakthrough occurred recently when Japanese astronomers found a new possibility that suggested a layer of gas between the ice and liquid which allowed both to coexist in nature.

Sputnik platina which was under the New Horizons probe detected a gravitational anomaly which suggests that there is a frozen ocean underneath. It could also explain its age, tectonic plates and other geographical features. The report has been published in the journal Nature Geoscience. In the paper, scientists mentioned that to maintain a liquid Ocean Pluto has to retain heat inside it and that it’s ice shell has to be cold.

The team suggested a hypothesis where they mentioned a gas-hydrate layer, an ice-like form of water and gas trapped within its lattice also called clathrate. A clathrate hydrate gas explains the long term survival of the ocean and shell thickness. Researchers have simulated conditions on Pluto with and without hydrate gas and modelled the thermal evaluation of the dwarf planet and how long would it take for the oceans to freeze completely and to form a uniformly thick layer of shell ice.

According to the simulations, without the gas hydrate layer, the oceans would freeze within 800 million years when animals were starting to evolve on earth. But when a gas hydrate layer was present it showed that oceans ceased to freeze. It acts as a thermal insulator while keeping the ice shell cold.

The most suitable gas for gas clathrate would be methane, making it a reserve of what we know on Earth as flammable ice. The methane is derived from precursor bodies and organic material from the core of the planet. The simulations, however, does not support the observations by New Horizons and demonstrates how liquid oceans can even exist on the iciest planets. This is just another example which supports the diversity and vastness of our solar system.

Abludomelita obtusata

Presence of radioactive carbon found in crustaceans in oceanic trenches

The latest study published in the Journal of American Geophysical UnionGeophysical Research Letters provides evidence regarding the presence of radioactive carbon from the nuclear tests in the muscular tissues of the crustaceans that reside in the ocean trenches.

Organisms which reside in the oceanic trenches including Mariana Trench, the deepest point in the ocean incorporated this carbon in the molecules which comprise their bodies from as early as the 1950s. The study finds that the crustaceans inhabiting the deep oceanic trenches have been feeding on the body of these organisms after they fall to the ocean floor. This is a very alarming situation wherein the effects of human activities can be traced back even to deep ocean floors.

Ning Wang, lead author and geochemist in Chinese Academy of Sciences, Guangzhou, China remarked that even though the circulation of oceans takes several hundreds of years to bring the water containing carbon from the nuclear explosions to the ocean trenches, it can travel much faster through the food chain.

Weidong Sun, co-author of the study also pointed out that there is a presence of very strong interaction between the surface of the ocean and bottom. Thus the human activities can influence biosystems even till 11,000 metres. Thus we need to be careful about our activities.

These results have helped scientists in understanding how organisms have adjusted to the nutrient deficient conditions of the deep ocean. Scientists have observed that the crustaceans have adapted to the harsh conditions by having a slow metabolism which enables them to live for a long period of time.

The radioactive carbon, C-14 is created due to the interaction of cosmic rays with nitrogen present in the atmosphere. It is quite less abundant than non-radioactive carbon but can be detected in almost all organisms. Besides this, it is also used for determining the ages of fossils, archaeological samples.

The amount of carbon in the atmosphere has been doubled due to the nuclear weapon tests which were carried out in the 1950s. However, the levels dropped to some extent when these tests were stopped. Hence the levels in 1990 reduced to almost 20 percent of the pre-test levels.

In this study, researchers analysed the amphipods which were collected in 2017 from several locations such as  Mariana, New Britain Trenches in the Pacific Ocean which ranges as far as 11 kilometres below the surface. Amphipods are a group of small crustacean which gets their food by feeding on the dead organisms on the ocean floor.

The C-14 levels in amphipods were much more than that of the organic matter on the ocean floor. This helps in understanding how organisms adapt to the environment and increase their longevity.

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