Apollo asteroid

Apollo asteroids are a class of near-Earth asteroids (NEAs) whose orbits cross Earth's path. These asteroids have a mean distance from the Sun greater than or equal to 1 astronomical unit (AU), and their closest approach to the Sun (perihelion) is less than or equal to Earth's aphelion distance of 1.017 AU. This means they can encounter Earth's orbit when they are closest to the Sun.1

The discovery of NEAs like Apollo asteroids is crucial for understanding potential Earth impact hazards. While most NEAs are small, larger ones pose a significant threat. For example, asteroid 2024 YR4, classified as an Apollo asteroid, was initially estimated to have a small but non-zero chance of impacting Earth in 2032, with potential consequences comparable to large historical events. Ongoing astronomical surveys aim to detect and track these objects to assess and mitigate risks.21