Reference Terms
from Wikipedia, the free encyclopedia
Near-Earth asteroid
Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earth's orbit. Some NEAs' orbits intersect Earth's so they pose a collision danger. On the other hand, NEAs are most easily accessible for spacecraft from Earth; in fact, some can be reached with much less delta-v than it takes to reach the Moon. Two NEAs have been visited by spacecraft: 433 Eros, by NASA's Near Earth Asteroid Rendezvous probe, and 25143 Itokawa, by the JAXA Hayabusa mission.
Roughly 1000 near-Earth asteroids are known, ranging in size up to approximately 32 kilometres (1036 Ganymed). Tens of thousands probably exist, with estimates placing the number of NEAs larger than one kilometer in diameter at up to 2,000.
NEAs only survive in their orbits for 10 million to 100 million years. They are eventually eliminated by orbital decay and accretion by the Sun, collisions with the inner planets, or by being ejected from the solar system by near misses with the planets. Such processes should have eliminated them all long ago, so it is assumed they are resupplied on a regular basis by orbital migration of objects from the asteroid belt.
Related Stories
1
2
Space & Time News
November 11, 2025
Nov. 10, 2025 — New research from UBC Okanagan mathematically demonstrates that the universe cannot be simulated. Using Gödel’s incompleteness theorem, scientists found that reality requires “non-algorithmic understanding,” something no computation can ...
Nov. 2, 2025 — A team of astronomers used the James Webb Space Telescope to create the first 3D atmospheric map of an exoplanet. The fiery WASP-18b, a massive “ultra-hot Jupiter,” revealed striking temperature contrasts, including regions so hot they destroy ...
Oct. 30, 2025 — Scientists have developed a groundbreaking tool called Effort.jl that lets them simulate the structure of the universe using just a laptop. The team created a system that dramatically speeds up how researchers study cosmic data, turning what once ...
Oct. 29, 2025 — Tohoku University researchers have found a way to make quantum sensors more sensitive by connecting superconducting qubits in optimized network patterns. These networks amplify faint signals possibly left by dark matter. The approach outperformed ...
Oct. 27, 2025 — Two Sydney PhD students have pulled off a remarkable space science feat from Earth—using AI-driven software to correct image blurring in NASA’s James Webb Space Telescope. Their innovation, called AMIGO, fixed distortions in the telescope’s ...
Oct. 25, 2025 — A UCLA-led team has achieved the sharpest-ever view of a distant star’s disk using a groundbreaking photonic lantern device on a single telescope—no multi-telescope array required. This technology splits incoming starlight into multiple ...
Oct. 25, 2025 — Researchers propose that hydrogen gas from the early Universe emitted detectable radio waves influenced by dark matter. Studying these signals, especially from the Moon’s radio-quiet environment, could reveal how dark matter clumped together ...
Oct. 15, 2025 — 3I/ATLAS, a mysterious interstellar object racing toward the Sun, is baffling scientists with its speed and origin. Some researchers suggest it could even be alien-made, drawing comparisons to probes ...
Oct. 14, 2025 — High above the Sun’s blazing equator lie its mysterious poles, the birthplace of fast solar winds and the heart of its magnetic heartbeat. For decades, scientists have struggled to see these regions, hidden from Earth’s orbit. With the upcoming ...
Oct. 12, 2025 — A colossal northern asteroid impact billions of years ago likely shaped the Moon’s south polar region and explains its uneven terrain. Researchers found that the South Pole-Aitken Basin formed from a glancing northern strike, revealing deep ...
Oct. 12, 2025 — ESA’s Mars orbiters have observed comet 3I/ATLAS, only the third interstellar comet ever discovered. The faint, distant object revealed a glowing coma as it was heated by the Sun. Researchers are still studying the data to understand its makeup ...
Oct. 9, 2025 — Mars may look calm, but new research reveals it’s a world of fierce winds and swirling dust devils racing at hurricane-like speeds. Using deep learning on thousands of satellite images from European orbiters, scientists have discovered that ...
Latest Headlines
updated 12:56 pm ET
Nov. 11, 2025 — New simulations suggest magnetic fields hold the key to forming black holes that defy known mass limits. When powerful magnetic forces act on a collapsing, spinning star, they eject vast amounts of ...
Nov. 10, 2025 — XRISM’s observations of GX13+1 revealed a slow, fog-like wind instead of the expected high-speed blast, challenging existing models of radiation-driven outflows. The discovery hints that ...
Nov. 10, 2025 — From Cassini’s awe-inspiring flybys to cutting-edge simulations, scientists are decoding the secrets of Enceladus’s geysers. Supercomputer models show the icy moon’s plumes lose less mass than ...
Nov. 9, 2025 — Astronomers have discovered phosphine gas in the atmosphere of an ancient brown dwarf, Wolf 1130C, using the James Webb Space Telescope. The finding is puzzling because phosphine, a potential ...
Nov. 9, 2025 — New supercomputer simulations hint that dark energy might be dynamic, not constant, subtly reshaping the Universe’s structure. The findings align with recent DESI observations, offering the ...
Nov. 9, 2025 — NASA’s Cassini mission has revealed surprising heat flow at Enceladus’ north pole, showing the moon releases energy from both ends. This balance of heat could allow its subsurface ocean to remain ...
Nov. 8, 2025 — Researchers are using black hole shadows to challenge Einstein’s theory of relativity. With new simulations and future ultra-sharp telescope images, they may uncover signs that his famous equations ...
Nov. 7, 2025 — A colossal black hole 10 billion light-years away has been caught devouring one of the universe’s biggest stars, unleashing a flare 30 times brighter than any seen before. The flare, detected by ...
Nov. 7, 2025 — Using CERN’s Super Proton Synchrotron, researchers generated plasma fireballs to simulate blazar jets. The beams stayed stable, suggesting plasma ...
Nov. 6, 2025 — A new theory claims dark matter and dark energy don’t exist — they’re just side effects of the universe’s changing forces. By rethinking gravity and cosmic timelines, it could rewrite our ...