Reference Terms
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Circle of latitude
On the Earth, a circle of latitude or parallel is an imaginary east-west circle that connects all locations with a given latitude. The position on the circle of latitude is given by the longitude. Each is perpendicular to all meridians at the intersection points. Those parallels closer to the poles are smaller than those at or near the Equator.
For a low latitude a circle of latitude can be said to be a line around the Earth, while at a high latitude it is a circle around a pole. Circles of latitude are often used as boundaries between countries or regions.
The five major circles of latitude are, starting from the North Pole and finishing at the South Pole; the Arctic Circle, the Tropic of Cancer, the Equator, the Tropic of Capricorn and the Antarctic Circle.
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Earth & Climate News
October 25, 2025
Oct. 25, 2025 — For the first time, scientists have seen a subduction zone actively breaking apart beneath the Pacific Northwest. Seismic data show the oceanic plate tearing into fragments, forming microplates in a slow, step-by-step collapse. This process, once ...
Oct. 24, 2025 — Scientists have discovered that El Niño and La Niña could become far more powerful and predictable as the planet warms. By 2050, the tropical Pacific may hit a tipping point, locking ENSO into strong, rhythmic oscillations that synchronize with ...
Oct. 23, 2025 — In the mist-shrouded mountains of New Guinea, a Czech researcher has achieved a world-first — capturing photos, video, and data of the elusive Subalpine Woolly Rat, Mallomys istapantap. Once known only from museum specimens, this giant, shaggy ...
Oct. 23, 2025 — Sea levels are rising faster than at any time in 4,000 years, scientists report, with China’s major coastal cities at particular risk. The rapid increase is driven by warming oceans and melting ice, while human activities like groundwater pumping ...
Oct. 23, 2025 — Scientists have uncovered evidence that megaquakes in the Pacific Northwest might trigger California’s San Andreas Fault. A research ship’s navigational error revealed paired sediment layers ...
Oct. 22, 2025 — Common dolphins in the North Atlantic are living significantly shorter lives, with female longevity dropping seven years since the 1990s. Researchers found this decline by analyzing stranded dolphins, revealing a 2.4% drop in population growth ...
Oct. 21, 2025 — Scientists are taking the once-radical concept of dimming the sun through stratospheric aerosol injection (SAI) seriously, but a Columbia University team warns that reality is far messier than models suggest. Their study reveals how physical, ...
Oct. 21, 2025 — Melting Arctic ice is revealing a hidden world of nitrogen-fixing bacteria beneath the surface. These microbes, not the usual cyanobacteria, enrich the ocean with nitrogen, fueling algae growth that supports the entire marine food chain. As ice ...
Oct. 19, 2025 — Researchers have developed a light-emitting sugar probe that exposes how marine microbes break down complex carbohydrates. The innovative fluorescent tool allows scientists to visualize when and where sugars are degraded in the ocean. This ...
Oct. 13, 2025 — Humanity has reached the first Earth system tipping point, the widespread death of warm-water coral reefs, marking the beginning of irreversible planetary shifts. As global temperatures move beyond 1.5°C, the world risks cascading crises such as ...
Oct. 12, 2025 — Researchers are finding extraordinary new uses for what we throw away. Beet pulp may help crops resist disease, while composted coconut fibers could replace peat moss. Discarded radish and beet greens are rich in bioactive compounds that boost gut ...
Oct. 10, 2025 — Coccolithophores, tiny planktonic architects of Earth’s climate, capture carbon, produce oxygen, and leave behind geological records that chronicle our planet’s history. European scientists are uniting to honor them with International ...
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Oct. 19, 2025 — Mars’ north polar vortex locks its atmosphere in extreme cold and darkness, freezing out water vapor and triggering a dramatic rise in ozone. Scientists found that the lack of sunlight and moisture ...
Oct. 17, 2025 — Researchers have discovered chemical fingerprints of Earth's earliest incarnation, preserved in ancient mantle rocks. A unique imbalance in potassium isotopes points to remnants of “proto Earth” ...
Oct. 16, 2025 — Ryugu’s samples reveal that water activity on asteroids lasted far longer than scientists thought, possibly reshaping theories of how Earth gained its oceans. A billion-year-old impact may have ...
Oct. 16, 2025 — Researchers discovered a new field of ancient tektites in South Australia, revealing a long-forgotten asteroid impact. These 11-million-year-old glass fragments differ chemically and geographically ...
Oct. 16, 2025 — New research reveals that Earth’s continents owe their stability to searing heat deep in the planet’s crust. At more than 900°C, radioactive elements shifted upward, cooling and strengthening ...
Oct. 12, 2025 — Supershear earthquakes, moving faster than seismic waves, could cause catastrophic shaking across California. USC researchers warn that many faults capable of magnitude 7 quakes might produce these ...
Oct. 12, 2025 — Geophysicists have modeled how Earth’s magnetic field could form even when its core was fully liquid. By removing the effects of viscosity in their simulation, they revealed a self-sustaining ...
Oct. 10, 2025 — China’s Guangdong Province is battling its worst-ever chikungunya outbreak, with thousands of infections spreading across major cities and nearby regions. Transmitted by Aedes mosquitoes, the ...
Oct. 9, 2025 — Tree swallows in polluted U.S. regions are accumulating high levels of “forever chemicals.” These durable pollutants, used in firefighting foams and consumer products, are found everywhere from ...
Oct. 8, 2025 — The Amazon has suffered its most destructive fire season in more than two decades, releasing a staggering 791 million tons of carbon dioxide—on par with Germany’s annual emissions. Scientists ...