Types of solar eclipses: classification and distinctions between partial, annular, total, and hybrid

A new analysis of minerals collected in the Colônia Crater, located in the extreme south of São Paulo (SP), provided robust evidence that this geological formation resulted from an asteroid impact on Earth.

Researchers from the University of São Paulo (USP) and the Institute of Environmental Research managed to identify, for the first time at that site, shock micro-marks in zircon grains. This mineral is notable for its ability to retain traces of extreme events.

The Colônia Crater, situated in Parelheiros, has an approximate diameter of 3.6 kilometers and contains the Vargem Grande neighborhood. Although the structure was detected by aerial images in the 1960s and has been under study for over sixty years, the new work published in April in the scientific journal Earth and Planetary Science strengthens the theory that the crater was formed by an asteroid collision.

Among the discovered characteristics are the so-called planar deformation features, or PDFs. These are microscopic structures generated by the propagation of shock waves through the mineral. Victor Velázquez Fernandez, a professor at the School of Arts, Sciences and Humanities (EACH) at USP and author of the study, explains that PDFs function as a characteristic signature of impacts capable of creating craters on the Earth's surface.

Additionally, scientists observed other modifications in the crystals, such as recrystallization, crystallographic disorientation, disturbances in growth zones, and granular textures. The phenomenon known as shock metamorphism occurs when a rock or mineral is exposed to extremely high pressure in a very short period, a condition often caused by an asteroid colliding with the Earth's surface.

This impact releases a vast amount of energy, generating shock waves that travel through rocks near the point of collision. Such waves have the power to alter the composition of minerals, leaving microscopic marks that persist for millions of years. Zircon is particularly valuable in this type of investigation due to its great resistance, allowing the preservation of geological information even after weathering and transformations over time.

Thus, the detection of these deformations in the grains offers direct mineralogical proof that the rocks of the Colônia Crater underwent the extreme conditions typical of an impact. Although previous research already pointed to signs of impact—including deformations in quartz and mica, as well as spherules and rocks linked to the event—the contribution of USP lies in adding evidence of shock metamorphism preserved in zircon crystals, reinforcing that the formation did not result from common geological processes, such as regional tectonic deformations.

The Colônia Crater is a circular depression with approximately 3.6 kilometers in diameter. The area was listed by Condephaat in 2003 and designated a Geological Monument in 2009. Currently, part of this formation is inhabited by the Vargem Grande neighborhood, characterized by green areas, roads with different slopes, and residences located within the circular structure of the crater.

Long-time residents testify to the growth of the neighborhood and have lived for decades with the narrative that their homes are situated within a structure originated by an extraterrestrial event. Ozéias de Freitas Ramos, a visual artist who has lived in the area since childhood, told g1 that his family moved to the neighborhood in the 1980s. He expressed pride in the confirmation of the formation's origin, although he still pointed out challenges regarding infrastructure, environment, and availability of cultural equipment.

The region also hosts the Joaquim Fonseca Lopes Penitentiary, inaugurated in 2009 on an area of approximately eight thousand square meters, which, according to data from the Penitentiary Administration Secretariat, houses 1,451 inmates in closed regime.

The name of the formation derives from Colônia Paulista, a neighboring neighborhood that served as the initial reference for early researchers of the structure. Geographer Rodrigo Martins clarifies that the area was originally known as Colônia Alemã, a settlement linked to a foreign colonization project in Brazil during the imperial period. During World War II, the name was changed to Colônia Paulista due to nomenclature changes related to Germany, and the geological formation adopted the name of the neighborhood used as a reference.

The Earth Impact Database catalogs confirmed impact structures globally, currently containing 190 records. In Brazil, eight impact structures are considered confirmed, with Colônia being one of only two inhabited craters on the planet; the other is the Ries Crater in Germany, which covers about 24 kilometers in diameter and has over one hundred thousand inhabitants.

In summary, this new research not only corroborates the extraterrestrial origin of the Colônia Crater but also demonstrates the capacity of microscopic minerals to preserve evidence of remote events in geological time, even after urban development over the structure.

A new scientific study has established that diatoms, which are an important biological indicator of river health, are much less demanding about their habitat than previously assumed. The research, conducted by the Agharkar Research Institute, Savitribai Phule Pune University, and the Canadian Museum of Nature, Canada, demonstrated that these microscopic algae show almost no preference when growing on both submerged rocks and aquatic plant stems.

The results suggest that researchers can adopt a more flexible approach when sampling these organisms to detect river pollution. Instead of looking for specific types of rocks, which is the current gold standard in many monitoring guidelines, any available surface can now be reliably used, significantly simplifying and reducing the cost of sampling in tropical rivers.

Diatoms are single-celled algae enclosed in silica shells. Since different diatom species have very specific tolerance thresholds for pollutants, acidity, and nutrients, they are often used as indicators of ecosystem health. Decades of research in Europe and North America have often indicated differences between diatoms living on rocks and those living on plants, requiring scientists to exercise extreme caution when collecting samples to avoid a distorted picture of the environment.

However, the new study, carried out in the Western Ghats—one of the world's most important biodiversity hotspots—challenges this assumption for tropical systems. By analyzing 40 sites in the Western Ghats, the research group found that diatom communities on both types of surfaces were virtually identical.

Scientists discovered that factors such as phosphorus levels, water temperature, and electrical conductivity influence the formation of diatom communities thirteen times more strongly than the type of surface to which the algae are attached. Many streams in the Western Ghats showed naturally high levels of phosphorus—a nutrient that often limits diatom growth elsewhere. This high nutrient availability, combined with relatively stable tropical temperatures, apparently creates a selective pressure effect.

Local water conditions function as a biological filter, determining which species can survive at a particular point in the river, regardless of whether they settle on a boulder or a leaf. The study also revealed a striking level of regional uniqueness: over 57% of species are endemic to this region, meaning they are found only in this part of India. This level of endemism is significantly higher than what is typically observed in rivers in Europe or North America.

The team also found that under the stable warm conditions of the Western Ghats, diatoms tend to be generalists rather than specialists. In light of growing pressure on the Western Ghats from urbanization, agriculture, and climate change, the need for rapid and reliable water monitoring has never been more pressing. By demonstrating the flexibility of diatoms in using habitats, this study allows for the development of substrate-independent monitoring methods.

This means that even in muddy rivers where rocks are buried, or in fast-flowing currents where plants are scarce, scientists can obtain accurate data on water quality using whatever is at hand. Such adaptability facilitates continuous monitoring of water resources by local communities and conservation activists, ensuring the preservation of this global hotspot's unique biodiversity for future generations.

On June 30, 2020, Southern Brazil faced one of the most severe mornings in its recent history due to the passage of bomb cyclones. Wind gusts exceeding 100 km/h resulted in 13 deaths, left nearly 3,000 people displaced, and caused power outages in areas of Rio Grande do Sul, Santa Catarina, and Paraná.

This disaster was attributed to the phenomenon known as bomb cyclones, or bombogenesis, which occurs from the accelerated meeting between large masses of hot and cold air. This process involves a cycle of air heating and rising, followed by cooling and sinking, a movement called convection. This repetition generates a sudden decrease in atmospheric pressure at the center of the system, which gives the cyclone its rapid strength, justifying the name 'bomb.'

Several municipalities were impacted by the passage of this cyclone that year. In Santa Catarina, cities such as Florianópolis and Balneário Camboriú suffered destruction caused by the phenomenon.

Impact in Santa Catarina

Santa Catarina was the most affected state, recording 11 confirmed deaths. Data from the Regional Civil Defense Coordinators on the day of the event pointed to 25 affected municipalities, a number that increased to 184 municipalities, representing 62% of Santa Catarina's cities. In Chapecó, a 78-year-old woman died after being struck by a tree. In Santo Amaro da Imperatriz, a pedestrian did not survive after being hit by high-voltage wires resulting from a fallen tree.

The subsequent early mornings required the Santa Catarina Government to declare a state of public calamity. On July 1, winds reached 90 km/h, and 369,600 residences remained without power for more than 24 hours after the first blackout.

Situation in Rio Grande do Sul and Paraná

In Rio Grande do Sul, the bomb cyclone left 2,331 people homeless or displaced in 23 cities, due to flooding and strong winds. In Porto Alegre, although the gusts were milder, around 80 km/h, there was falling poles and trees, blockage of at least 28 roads, and structural damage to buildings.

In Paraná, the cyclone caused damage in at least 84 of the 399 municipalities, according to the Civil Defense report, and registered at least one death. In Curitiba, winds close to 100 km/h knocked down trees and left 193,000 properties without electricity.

The effects in the Southeast were milder, as the cyclone only touched the state of São Paulo during its trajectory in the region.

Climate Trends and Origin of the Phenomenon

Concern about the arrival of new bomb cyclones is high, especially in the South regions and parts of the Southeast, considering the year 2026. In South America, these extratropical cyclones generally originate in the ocean, near the coasts of Argentina and Uruguay. The 2020 episode started near Paraguay and followed the southern Brazilian coast, dissipating into the sea.

With global warming, there is a trend for the impacts of bomb cyclones to become more intense. This occurs because the increase in temperature in the oceans and atmosphere tends to accentuate the contrast between the hot and cold air masses that cause the phenomenon. It is relevant to note that the cyclone preceding the 2020 one, which occurred in 2016, was less severe. Furthermore, a report from the World Meteorological Organization (WMO) points out that humanity is experiencing the ten hottest years in its recent history.