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163348 (2002 NN4): A Near-Earth Asteroid

  • 06 Jun 2020
  • 6 min read

Why in News

Recently, the National Aeronautics and Space Administration (NASA) has announced that a giant asteroid called as 163348 (2002 NN4), is expected to pass Earth on 6th June 2020.

  • However, it is approaching the Earth within the safe limit of distance.

Key Points

  • 163348 (2002 NN4):
    • It was discovered in July 2002 and is expected to approach the earth in June 2020.
    • The asteroid is estimated to be between 250-570 meters in diameter.
    • The asteroid is a Near-Earth Object and classified as a Potentially Hazardous Asteroid (PHA).
  • Near-Earth Objects (NEOs):
    • NEOs are comets and asteroids pushed by the gravitational attraction of nearby planets into orbits which allow them to enter the Earth’s neighbourhood.
    • These objects are composed mostly of water ice with embedded dust particles.
    • NEOs occasionally approach close to the Earth as they orbit the Sun.
    • NASA’s Center for Near-Earth Object Study (CNEOS) determines the times and distances of these objects, when their approach to the Earth is close, through the Asteroid Watch Widget.
  • Potentially Hazardous Asteroid (PHA):
    • It means that an asteroid has the potential to make threatening close approaches to the Earth.
    • Specifically, all asteroids with a Minimum Orbit Intersection Distance (MOID) of 0.05 AU (which is about 7,480,000 Km) or less and an Absolute Magnitude (H) of 22.0 (about 150 mt in diameter) or less are considered PHAs.
      • Minimum Orbit Intersection Distance is a method for calculating the minimum distance between two almost overlapping elliptical orbits.
      • The Astronomical Unit (AU) is the distance between the Earth and the Sun and is roughly 150 million km.
      • The absolute magnitude is a measure of the star's luminosity i.e. the total amount of energy radiated by the star every second.
  • Chances of hitting the earth and related Concerns:
    • According to NASA, the objects with large size pose a great risk to Earth due to the level of devastation and the impact they can cause.
    • Less than half of the estimated 25,000 NEOs that are 140 metres or larger in size have been found to date.
      • NASA’s Near-Earth Object Observations Program finds, tracks and characterises over 90% of the predicted number of NEOs that are 140 metre or larger in size.
    • However, no asteroid larger than 140 metre has a “significant” chance of hitting the Earth for the next 100 years.


  • Asteroids orbit the Sun and are small bodies in the solar system.
  • They are made up of metals and rocks.
  • They tend to have shorter and elliptical orbits.
  • They do not produce a coma or tail atmosphere.
  • The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars.


  • Comets also orbit the Sun and are relatively small bodies of the solar system.
  • They are made up of ice and hydrocarbons.
  • Comets have an eccentric orbit.
  • When comets approach the sun, some part of their ice melts and the other materials vapourise due to the heat of the sun. This results in a glowing halo that extends outwards through space.
    • Therefore, a thin atmospheric tail is formed when close to the Sun.


  • The scientific interest in comets and asteroids is largely due to their status as relatively unchanged remnant debris from the solar system formation process over 4.6 billion years ago. Therefore, they offer clues about the chemical mixture from the planets formed.
  • Significantly, among all the reasons that will eventually cause the extinction of life on Earth, an asteroid hit is widely acknowledged as one of the likeliest.
    • Over the years, scientists have suggested different ways to ward off such a hit, such as blowing up the asteroid before it reaches Earth, or deflecting it off its Earth-bound course by hitting it with a spacecraft.

Way Forward

  • It is not necessary that asteroids classified as PHAs will impact the Earth. It only means there is a possibility of a threat.
  • By monitoring these PHAs and updating their orbits as new observations, it is possible to predict the close-approach statistics and thus their Earth-impact threat.

Source: IE

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