NASA has issued a warning that a huge “Asteroid 2020 ND” will move past Earth on July 24.
Try this question from CSP 2014:
Q.What is a coma, in the content of astronomy?
(a) Bright half of material on the comet
(b) Long tail of dust
(c) Two asteroids orbiting each other
(d) Two planets orbiting each other
What are Asteroids?
- Asteroids are small, rocky objects that orbit the Sun. They are leftover from the formation of our solar system.
- Although asteroids orbit the Sun like planets, they are much smaller than planets.
- There are lots of asteroids in our solar system. Most of them live in the main asteroid belt—a region between the orbits of Mars and Jupiter.
- Some asteroids go in front of and behind Jupiter. They are called Trojans.
- Asteroids that come close to Earth are called Near-Earth Objects, NEOs for short. NASA keeps a close watch on these asteroids.
Asteroid 2020 ND
- The 2020 ND is about 170 metres-long.
- It will be as close as 0.034 astronomical units (5,086,328 kilometres) to our planet and is travelling at a speed of 48,000 kilometres per hour.
- Its distance from Earth has placed it in the “Potentially Hazardous Asteroids (PHAs)” category.
How are PHAs defined?
- PHAs are currently defined based on parameters that measure the asteroid’s potential to make threatening close approaches to the Earth.
- NASA classifies objects like these as ‘near-Earth objects’ (NEOs) as they get nudged by other planets’ gravitational attraction resulting in their proximity to our solar system.
- It is not necessary that asteroids classified as PHAs will impact the Earth. It only means there is a possibility for such a threat.
Can they be deflected?
- Over the years, scientists have suggested different ways to ward off such threats, such as blowing up the asteroid before it reaches Earth or deflecting it off its Earth-bound course by hitting it with a spacecraft.
- The most drastic measure undertaken so far is the Asteroid Impact and Deflection Assessment (AIDA), which includes NASA’s Double Asteroid Redirection Test (DART) mission and the ESA’s Hera.
- Both mission’s target is Didymos, a binary near-Earth asteroid, one of whose bodies is of the size that could pose the most likely significant threat to Earth.
- In 2018, NASA announced that it had started the construction of DART, which is scheduled to launch in 2021 with an aim to slam into the smaller asteroid of the Didymos system at around 6 km per second in 2022.
- Hera, which is scheduled to launch in 2024, will arrive at the Didymos system in 2027 to measure the impact crater produced by the DART collision and study the change in the asteroid’s orbital trajectory.
Back2Basics: Near-Earth objects (NEOs)
- NEOs are comets and asteroids nudged by the gravitational attraction of nearby planets into orbits which allows them to enter the Earth’s neighbourhood.
- These objects are composed mostly of water ice with embedded dust particles, and 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 as and when their approach to the Earth is close.