Asteroid 2002MN gives Earth its closest shave in years

On Friday 14 June, an asteroid the size of a football pitch made one of the
closest ever recorded approaches to Earth. Astronomers working on the LINEAR
search programme, near Socorro, New Mexico first detected the giant rock on
17 June, a few days after its close approach.

The Near Earth Object, known to astronomers as ‘2002MN’, was travelling at
over 10 km/s (23,000 miles per hour) when it passed Earth at a distance of
around 120,000 km (75,000 miles), bringing it well inside the Moon’s orbit.
The last time a known asteroid passed this close was back in December 1994.

Asteroids are typically too small and distant to measure their size directly
from Earth, so scientists use the amount of light they reflect, along with a
basic understanding of the materials they are made of, to estimate their
size. With a diameter between 50-120 metres, 2002 MN is a lightweight among
asteroids and incapable of causing damage on a global scale, such as the
object associated with the extinction of the dinosaurs.

However, if it had hit the Earth, 2002MN may have caused local devastation
similar to that which occurred in Tunguska, Siberia in 1908, when 2000
square kilometres of forest were flattened. Whilst the vast majority of NEOs
discovered do not come this close, such near misses do highlight the
importance of detecting these objects. This reminder comes in a week when
the UK telescopes on La Palma are being tested to search for NEOs.

Brief Description of Object

• Object Designation: 2002MN
  
• Date of First Observation: 17/06/02
  
• Number of Observations: 14
  
• Search Team: LINEAR (Lincoln Near Earth Asteroid Research)
  
• Date of Closest Approach: 14/06/02
  
• Closest Approach Distance: 0.000797 AUÊ or 119,229 km (0.3 Lunar Distances)
  
• Asteroids Velocity Relative to Earth at Closest Approach: 10.58 km/s (23,667 miles per hour)
  
• Estimated Diameter of Asteroid: 50-120 metres
  
• Orbital Period: 894.9 days