Reference Terms
from Wikipedia, the free encyclopedia
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. This is the parallel of latitude that (in 2000) runs 66.56083 degrees north of the Equator. Everything north of this circle is known as the Arctic, and the zone just to the south of this circle is the Northern Temperate Zone.
The Arctic Circle marks the southern extremity of the polar day (24 hour sunlit day) of the summer solstice in June and the polar night (24 hour sunless night) of the winter solstice in December. Within the Arctic Circle, the Sun is above the horizon for 24 continuous hours at least once per year, in conjunction with the Arctic's Summer Solstice. Likewise, in conjunction with the Arctic’s Winter Solstice, the Arctic sun will be below the horizon for at least 24 continuous hours.
Related Stories
1
2
Earth & Climate News
October 5, 2025
Oct. 5, 2025 — New research reveals that deep-sea mining could dramatically threaten 30 species of sharks, rays, and ghost sharks whose habitats overlap with proposed mining zones. Many of these species, already at risk of extinction, could face increased dangers ...
Oct. 3, 2025 — Billions of years ago, Earth’s atmosphere was hostile, with barely any oxygen and toxic conditions for life. Researchers from the Earth-Life Science Institute studied Japan’s iron-rich hot springs, which mimic the ancient oceans, to uncover how ...
Oct. 2, 2025 — In 2020, California’s Creek Fire became so intense that it generated its own thunderstorm, a phenomenon called a pyrocumulonimbus cloud. For years, scientists struggled to replicate these explosive fire-born storms in climate models, leaving major ...
Oct. 2, 2025 — Swiss glaciers lost nearly 3% of their volume in 2025, following a snow-poor winter and scorching summer heatwaves. The melt has been so extreme that some glaciers lost more than two meters of ice thickness in a single season. Scientists caution ...
Oct. 1, 2025 — Fungi may have shaped Earth’s landscapes long before plants appeared. By combining rare gene transfers with fossil evidence, researchers have traced fungal origins back nearly a billion years earlier than expected. These ancient fungi may have ...
Sep. 26, 2025 — Scientists have uncovered an unexpected witness to Earth’s distant past: tiny iron oxide stones called ooids. These mineral snowballs lock away traces of ancient carbon, revealing that oceans between 1,000 and 541 million years ago held far less ...
Sep. 26, 2025 — Scientists found that biochar doesn’t just capture pollutants, it actively destroys them using direct electron transfer. This newly recognized ability accounts for up to 40% of its cleaning power and remains effective through repeated use. The ...
Sep. 26, 2025 — Bio-tar, once seen as a toxic waste, can be transformed into bio-carbon with applications in clean energy and environmental protection. This innovation could reduce emissions, create profits, and solve a major bioenergy industry ...
Sep. 26, 2025 — Electrons flow underground in ways far more extensive than once believed, forming networks that link distant chemical zones. Minerals, organic molecules, and specialized bacteria can act as bridges, ...
Sep. 24, 2025 — Rice, a staple for billions, is one of the most resource-hungry crops on the planet—but scientists may have found a way to change that. By applying nanoscale selenium directly to rice plants, researchers dramatically improved nitrogen efficiency, ...
Sep. 24, 2025 — Diamonds hitch a ride to the surface through explosive kimberlite eruptions, powered by volatile-rich magmas. New simulations show that carbon dioxide and water are the secret ingredients that make these eruptions ...
Sep. 23, 2025 — A long-term study in Colorado reveals that insect populations are plummeting even in remote, undisturbed areas. Over two decades, flying insect abundance dropped by more than 70%, closely linked to rising summer temperatures. The results suggest ...
Latest Headlines
updated 12:56 pm ET
Oct. 2, 2025 — A massive quake struck Calama, Chile, in 2024, surprising scientists with its unusual depth and destructive power. Unlike typical deep quakes, it broke past thermal limits and triggered an intense ...
Sep. 23, 2025 — South African diamonds have revealed nickel-rich metallic inclusions, offering the first direct evidence of reactions predicted to occur deep in Earth’s mantle. The study shows how oxidized melts ...
Sep. 22, 2025 — A team at RMIT University has created a cement-free construction material using only cardboard, soil, and water. Strong enough for low-rise buildings, it reduces emissions, costs, and waste compared ...
Sep. 22, 2025 — A sweeping review from NYU Langone Health reveals that everyday exposure to plastics—especially during childhood—poses lasting risks for heart ...
Sep. 22, 2025 — Researchers found that ice can trigger stronger chemical reactions than liquid water, dissolving iron minerals in extreme cold. Freeze-thaw cycles amplify the effect, releasing iron into rivers and ...
Sep. 21, 2025 — University of Maine researchers developed a new process to make HBL, a key ingredient in many medicines, from renewable glucose instead of petroleum. The approach not only lowers drug production ...
Sep. 20, 2025 — In Texas, biologists have documented an extraordinary bird — the natural hybrid offspring of a green jay and a blue jay. Once separated by millions of years of evolution and distinct ranges, the ...
Sep. 20, 2025 — Insects are essential for ecosystems, but mounting evidence suggests many populations are collapsing under modern pressures. A new study used cutting-edge genomic techniques on museum specimens to ...
Sep. 19, 2025 — Egg-eating worms living on Chesapeake Bay blue crabs may hold the key to smarter fishery management. Once thought to be a threat, these parasites ...
Sep. 19, 2025 — Wildfires are no longer a seasonal nuisance but a deadly, nationwide health crisis. Fueled by climate change, smoke is spreading farther and lingering longer, with new research warning of tens of ...