Reference Terms
from Wikipedia, the free encyclopedia
Axial tilt
Axial tilt is an astronomical term regarding the inclination angle of a planet's rotational axis in relation to a perpendicular to its orbital plane. It is also called axial inclination or obliquity. The axial tilt is expressed as the angle made by the planet's axis and a line drawn through the planet's center perpendicular to the orbital plane.
The axial tilt may equivalently be expressed in terms of the planet's orbital plane and a plane perpendicular to its axis. In our solar system, the Earth's orbital plane is known as the ecliptic, and so the Earth's axial tilt is officially called the obliquity of the ecliptic.
The Earth has an axial tilt of about 23 degrees 27’. The axis is tilted in the same direction throughout a year; however, as the Earth orbits the Sun, the hemisphere (half part of earth) tilted away from the Sun will gradually come to be tilted towards the Sun, and vice versa. This effect is the main cause of the seasons (see effect of sun angle on climate). Whichever hemisphere is currently tilted toward the Sun experiences more hours of sunlight each day, and the sunlight at midday also strikes the ground at an angle nearer the vertical and thus delivers more heat.
Related Stories
1
2
Earth & Climate News
December 12, 2025
Dec. 12, 2025 New research shows that crops are far more vulnerable when too much rainfall originates from land rather than the ocean. Land-sourced moisture leads to weaker, less reliable rainfall, heightening drought risk. The U.S. Midwest and East Africa are ...
Dec. 12, 2025 A sudden, unexplained mass die-off is decimating sea urchins around the world, including catastrophic losses in the Canary Islands. Key reef-grazing species are reaching historic lows, and their ability to reproduce has nearly halted in some ...
Dec. 12, 2025 Fossils from Qatar have revealed a small, newly identified sea cow species that lived in the Arabian Gulf more than 20 million years ago. The site contains the densest known collection of fossil sea cow bones, showing that these animals once thrived ...
Dec. 11, 2025 Researchers found that eroded lava rubble beneath the South Atlantic can trap enormous amounts of CO2 for tens of millions of years. These porous breccia deposits store far more carbon than previously sampled ocean crust. The discovery reshapes how ...
Dec. 11, 2025 Scientists tracking young Arizona Bald Eagles found that many migrate north during summer and fall, bucking the traditional southbound pattern of most birds. Their routes rely heavily on historic stopover lakes and rivers, and often extend deep into ...
Dec. 10, 2025 Researchers have uncovered surprising evidence that the deep ocean’s carbon-fixing engine works very differently than long assumed. While ammonia-oxidizing archaea were thought to dominate carbon fixation in the sunless depths, experiments show ...
Dec. 10, 2025 Researchers discovered that unusually high temperatures can hinder early childhood development. Children living in hotter conditions were less likely to reach key learning milestones, especially in reading and basic math skills. Those facing ...
Dec. 9, 2025 Scientists discovered a small protein region that determines whether plants reject or welcome nitrogen-fixing bacteria. By tweaking only two amino acids, they converted a defensive receptor into one that supports symbiosis. Early success in barley ...
Dec. 8, 2025 A newly analyzed set of climate data points to a major volcanic eruption that may have played a key role in the Black Death’s arrival. Cooling and crop failures across Europe pushed Italian states to bring in grain from the Black Sea. Those ...
Dec. 7, 2025 A century-old North Atlantic cold patch is now linked to a long-term slowdown in the AMOC, the climate-regulating conveyor belt of ocean water. Only weakened-AMOC models match observed temperature and salinity patterns, overturning recent model ...
Dec. 4, 2025 This year’s ozone hole over Antarctica ranked among the smallest since the early 1990s, reflecting steady progress from decades of global action under the Montreal Protocol. Declining chlorine levels and warmer stratospheric temperatures helped ...
Dec. 2, 2025 As the last Ice Age waned and the Holocene dawned, deep-ocean circulation around Antarctica underwent dramatic shifts that helped release long-stored carbon back into the atmosphere. Deep-sea sediments show that ancient Antarctic waters once trapped ...
Latest Headlines
updated 12:56 pm ET
Dec. 10, 2025 New research reveals that Earth’s solid inner core is actually in a superionic state, where carbon atoms flow freely through a solid iron lattice. This unusual behavior makes the core soft, ...
Dec. 7, 2025 A new radiocarbon study has clarified the timing of the colossal Thera eruption, placing it before Egypt’s New Kingdom. Researchers analyzed artifacts tied to Pharaoh Ahmose, gaining rare access to ...
Dec. 6, 2025 Scientists have discovered that complex life began evolving much earlier than traditional models suggested. Using an expanded molecular clock approach, the team showed that crucial cellular features ...
Dec. 4, 2025 Fresh evidence suggests early Earth wasn’t locked under a rigid stagnant lid but was already experiencing intense subduction. Ancient melt inclusions and advanced simulations point to continents ...
Dec. 3, 2025 Researchers recreated conditions from billions of years ago and found that Earth’s young atmosphere could make key molecules linked to life. These sulfur-rich compounds, including certain amino ...
Dec. 2, 2025 Dolichospermum, a type of cyanobacteria thriving in Lake Erie’s warming waters, has been identified as the surprising culprit behind the lake’s dangerous saxitoxins—some of the most potent ...
Dec. 1, 2025 Two decades of satellite and GPS data show the Thwaites Eastern Ice Shelf slowly losing its grip on a crucial stabilizing point as fractures multiply and ice speeds up. Scientists warn this pattern ...
Nov. 30, 2025 New findings show that some coastal regions will become far more acidic than scientists once thought, with upwelling systems pulling deep, CO2-rich waters to the surface and greatly intensifying ...
Nov. 28, 2025 Long-term inhalation of toxic air appears to dull the protective power of regular workouts, according to a massive global study spanning more than a decade and over a million adults. While exercise ...
Nov. 27, 2025 Human development and climate-driven sea level rise are accelerating global beach erosion and undermining the natural processes that sustain coastal ecosystems. Studies reveal that urban activity on ...