Asteroids are rocks that were left behind after the formation of Earth. Solar System. Approximately half a billion asteroids with sizes greater than four metres in diameter orbit the Sun, travelling through our Solar System at speeds up to about 30 kilometres per second – about the same speed as Earth.
Asteroids have a way of capturing public imagination. The following follows Hollywood has produced many moviesImagine the destruction they can cause if there is a large one that hits Earth.
Nearly every week, we see Online headlinesAsteroids that are the size of “a bus”, “truck”, or “vending machines”The size of half a giraffeYou can also get a whole giraffe. Asteroids have also been referred to as “city killers”, planet killers, and “Gods Of Chaos”.
Asteroids do pose a threat. The impact of an asteroid on Earth is well-known. asteroid, killing off most dinosaurs. Even a four-metre (half a half giraffe for example) object travelling at 60 kilometres per seconds is going to have a lot of power.
What are the actual risks? How many asteroids have hit Earth, and how many are expected to pass us?
What is the danger of a direct attack?
The NASA graphic summarizes the risks of an asteroids impacting Earth and its impact.
There are many more small asteroids compared to large asteroids. They also cause less damage.
NASA
Earth is subject to frequent, but low impact collisions, with small asteroids. However, rare, but high impact collisions, with large asteroids. Most of the time, small asteroids are largely broken up by Earth’s atmosphere and never reach the surface.
When a small asteroid (or meteoroid, an object smaller than an asteroid) hits Earth’s atmosphere, it produces a spectacular “fireball” – a very long-lasting and bright version of a shooting star, or meteor.
Meteorites are the pieces of the object that survive and fall to the ground. The majority of the object is destroyed in the atmosphere.
How many asteroids are flying past Earth at any given time?
This calculation will give you an idea of how many asteroids are likely to be close to the Earth.
The numbers above represent the number of asteroids which could potentially hit Earth in a given year. Let’s now look at four-metre-long asteroids. On average, an asteroid of four metres will cross the Earth’s surface once per year.
Double the area and you get two extra per year. The Earth’s diameter is 6,400km. A sphere that has twice the surface area will have a radius of 9,000km. So, approximately once per year, a four-metre asteroid will come within 2,600km of the surface of Earth – the difference between 9,000km and 6,400km.
You can expect two more per year if you double the Earth surface area. This is pretty close to Close approaches recorded in recent times.
Most of the asteroids reported in the media travel at distances much greater than a few thousand kilometers.
Astronomers look at anything passing nearer than Moon – approximately 300,000km – to be a “close approach”. An astronomer’s definition of “close” is different from what the general public would consider “close”.
In 2022, there are Close Approaches: 126We’ve already had a few in 2023. There are 50 of us so far.
Imagine asteroids larger than a kilometer in size. This logic can be used.
We can expect that for every impact which could have a serious impact on civilisation and occurs once every half million years, there will be thousands of close calls (closer to the Moon) during the same time period.
The next time this will happen is in 2029. asteroid 153814 (2001 WN5)It will be 248,700km away from Earth.
What can we do to reduce the threat?
Around 95% asteroids greater than one kilometer in size are believed to have been discovered. The skies are being constantly searched for the remaining 5%. Astronomers conduct extensive observations when a new one has been discovered to assess the threat it poses to Earth.
It is important to note that the word “you” means “you”. Torino ScaleThis scale goes from 0 to 10 for the likelihood of a collision.
At the moment, all objects are rated zero. To date, no known object has received a rating higher than 4 (a close-encounter that merits attention from astronomers).
The media should tell us the Torino Scale score of an asteroid, not about giraffes.
Technology has finally advanced to the point where we can do something in the event we face a large number on Torino Scale. Recently, DART collided with an asteroid and changed its trajectory.
With enough time in advance, it’s possible that this action could be used to protect the Earth from a collision.
Steven TingayJohn Curtin Professor of Radio Astronomy Curtin University
This article was originally published by The ConversationCreative Commons licensed. The Licensed Terms are available here. Original Article.
