Asteroid 2012 LZ1 was discovered in June 2012 and belongs to the category of NEO, and more specifically, PHA, due to its size and orbital proximity to Earth. Initially, its diameter was estimated at around 500 meters, but radar observations quickly corrected this to nearly 1 km.
2012 LZ1 is part of the Apollo group of asteroids. Its minimum orbit intersection distance (MOID) with Earth is only 0.0005 AU, or about 75,000 km, which is less than the Earth-Moon distance (≈ 384,000 km). During its June 14, 2012, flyby, it passed at 0.036 AU, or about 14 times the Earth-Moon distance, a safe but scientifically significant gap.
N.B.:
Apollo asteroids are a family of NEO whose orbits cross Earth's orbit, with a semi-major axis > 1 AU and a perihelion < 1.017 AU. They represent one of the main classes of near-Earth asteroids monitored by astronomers.
Asteroid 2012 LZ1, with an estimated diameter of nearly 1 km, is classified as a PHA. An object of this size, if it were to impact Earth, would release energy equivalent to hundreds of thousands of megatons of TNT, enough to cause planetary destruction and permanently alter the climate.
However, current orbital calculations indicate that no collision is expected in the near future. Its closest known approach, in June 2012, occurred at about 0.036 AU, or 14 times the Earth-Moon distance, which posed no immediate danger. Nevertheless, small uncertainties related to gravitational perturbations could, over the long term, deviate its trajectory, hence the need for continuous monitoring.
The hazard of a NEO is assessed based on several criteria: size, mass, relative impact velocity, entry angle into the atmosphere, and density. For 2012 LZ1, the critical factor is its kilometric size, which places it among objects whose potential impact would be rated at level 7 or 8 on the Turin Scale, meaning a global catastrophic event, although the actual probability remains almost zero to date.
N.B.:
The Turin Scale is a hazard indicator for near-Earth objects, ranging from 0 (no risk) to 10 (certain collision with global consequences).
| Parameter | Estimated Value | Comment |
|---|---|---|
| Diameter | ~1 km | Large object, capable of causing planetary effects |
| Impact Energy | ≈ 2 × 105 megatons TNT | Several orders of magnitude above the Chicxulub event (65 Ma) |
| Relative Velocity | ≈ 20 km/s | Typical value for Apollo-type NEOs |
| Turin Level | 7–8 (hypothetical) | Global catastrophic event if collision |
Sources: NASA CNEOS, Minor Planet Center, NASA – Turin Scale.
The early detection of 2012 LZ1 demonstrated the ability of ground-based observatories to quickly identify potentially hazardous objects. Thanks to radar observations conducted at Arecibo, astronomers were able to accurately determine its size, elongated shape, and rotation. This data is essential for assessing impact risk and planning possible deflection missions.
| Asteroid | Estimated Diameter | Minimum Distance (AU) | Discoverer |
|---|---|---|---|
| 2012 LZ1 | ~1 km | 0.0005 | Robert H. McNaught (1956-) |
| (99942) Apophis | ~370 m | 0.00025 | Roy A. Tucker (1951-) et al. |
| (29075) 1950 DA | ~1.3 km | 0.0026 | Carl A. Wirtanen (1910-1990) |
| (4179) Toutatis | ~2.7 km | 0.0064 | Christian Pollas (1954-) |
| (1862) Apollo | ~1.5 km | 0.025 | Karl Reinmuth (1892-1979) |
| (433) Eros | ~16.8 km | 0.148 | Gustav Witt (1866-1946) |
| (3200) Phaethon | ~5.1 km | 0.019 | Simon F. Green (1955-) and John K. Davies (1951-) |
Sources: NASA CNEOS, Minor Planet Center.
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