Asteroid alert! Several plane-sized objects hurtling towards Earth this week

A number of asteroids, each about the size of an airplane, are expected to make close approaches to Earth this week, NASA said in a statement earlier this week. Among the five asteroids, the largest is estimated to be 110 feet in diameter, while the closest will come within 447,000 miles of our planet.

What does it mean?

While it is common for large asteroids to pass by Earth at a safe distance, this week’s cluster is notable for the number of such encounters. Asteroid 2024 LU1, which is about 71 feet in diameter, made its closest approach on Monday (June 17), passing within 1,150,000 miles of Earth.

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The next close approach is scheduled for June 19, featuring the largest of the group, which will still be the farthest at a distance of 447,000 miles.

Which asteroids can be hazardous?

Asteroids are typically composed of rocky, dusty, and metallic materials. Most asteroids orbit within the main asteroid belt between Mars and Jupiter, but some follow paths that bring them closer to Earth. These near-Earth asteroids are part of a larger category known as near-Earth objects (NEOs), which also includes comets. NEOs are defined as celestial objects that come within 1.3 astronomical units of the Sun, and within 0.3 astronomical units of Earth’s orbit.

0.3 astronomical units is approximately 28 million miles.

For an asteroid to be classified as a potentially hazardous asteroid (PHA), it must be at least 140 metres in diameter and come within 7.48 million kilometres of Earth. An asteroid of this size that enters Earth's atmosphere and does not completely burn up could cause significant damage, especially if it were to strike a populated area.

Difference between asteroids and meteoroids

Asteroids are different from meteoroids. The former are smaller Sun-orbiting rocks or particles less than three feet in size. When a meteoroid enters Earth's atmosphere, it creates a light phenomenon known as a meteor. If any part of a meteoroid or asteroid survives the atmospheric entry and lands on Earth's surface, it is called a meteorite.

To monitor and prepare for potential asteroid threats, NASA’s Planetary Defense Coordination Office (PDCO) plays a crucial role. The PDCO is responsible for coordinating efforts and creating plans to protect Earth from the potential impacts of hazardous space objects.