Read a scientific article about asteroids to practise and improve your reading skills.

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In 2010, the planetary defence team at NASA had identified and logged 90 per cent of the asteroids near Earth measuring 1km wide. These 'near-Earth objects', or NEOs, are the size of mountains and include anything within 50 million kilometres of Earth's orbit. With an estimated 50 left to log, NASA says none of the 887 it knows about are a significant danger to the planet.


Now NASA is working towards logging some of the smaller asteroids, those measuring 140 metres wide or more. Of the 25,000 estimated asteroids of this size, so far about 8,000 have been logged, leaving 17,000 unaccounted for. Considering that a 19-metre asteroid that exploded above the city of Chelyabinsk in Russia in 2013 injured 1,200 people, these middle-sized asteroids would be a serious danger if they enter Earth's orbit.


Whether NASA can find the remaining middle-sized NEOs depends on getting the money to build NEOCam, a 0.5-metre space telescope which would use infrared light to locate asteroids. If it did get the money, it could probably achieve its goal in ten years. Once logged, the planetary defence team would still need to work out how to defend the planet against being hit by the truly worrying asteroids – the PHAs.


'Potentially Hazardous Asteroids' are rocks close enough to pass within 7.5 million kilometres of Earth's orbit. NASA has created a map of 1,400 PHAs, none of which are expected to be a threat in the next one hundred years. With technology already available, NASA can track these objects and make predictions about possible impact, at which point two defence solutions could be launched.


The first is DART – the Double Asteroid Redirection Test. Plans are scheduled to test DART on the moon of an asteroid called Didymos. 'Didymoon' is 150 metres wide, orbiting its 800-metre mother, and hopefully the impact of DART will knock it out of its orbit enough for Earth-based telescopes to pick up.


Another suggested defence against a PHA on course to hit Earth is to blow it up using a nuclear weapon. It may sound like a plot from a film, and it was the subject of the 1998 film Armageddon, but the Hypervelocity Asteroid Mitigation Mission for Emergency Response (HAMMER) is a genuine NASA proposal. The eight-ton rockets would be fired at an approaching asteroid with the hope of bumping it off course. If the asteroid was too close to Earth for this plan to work, the rockets would carry nuclear bombs to blow it up instead.


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Submitted by Vitaliy128 on Sun, 29/10/2023 - 09:36


It's a very tricky question) But I guess that if I found out that the asteroid was about to hit the Earth, I would probably share this information with my family and we would take all the necessary things (like our cats, money, and passports) and then hide somewhere in the basement. I feel like almost every one would act like me in this particular situation.

Submitted by betelf on Tue, 24/10/2023 - 14:31


I remember hearing about it in the recent past, and it didn't change anything in my life. I wonder if there's anything we can do as normal citizens?

Submitted by jmajo on Fri, 05/05/2023 - 16:13


I don’t know, I suppouse it depends on the size of the asteroid, if it’s like the one which exploded over Russia and it’s not expected to do it near my country, I would not be very concerned. But if it would expected to explode or crash near my country I certainly would go to the farest place from where it would be expected to explode as fast as possible. If the size of the asteroid is big enough to crash the Earth and end the life on it I suppose
I would grab my trumpet and play the last song of my existence.

Thanks for the lesson.
Great site!!

Submitted by Miss zahra on Mon, 10/04/2023 - 08:13


I do not know what to say. I t is exactly like that to say someone you have just one day to live. so I think I go somewhere to die on peace

Submitted by inaki07 on Sat, 25/02/2023 - 00:48


For the first question in the task 2, I don't understand why the answer is 'true'. The text says ' With an estimated 50 left to log, NASA says none of the 887 it knows about are a significant danger to the planet.' about asteroids that measure 1km wide.So, we don't know anything about 50 asteroids that measures 1 km wide. So, earth 'might' be in danger.

Hi inaki07,

The question says "Earth does not appear to be in any danger ...". "Appear" means "to be seen" (by somebody), so the question is asking whether any signs of danger have been observed or perceived (by the team at NASA). 

It is not asking whether danger really exists, in an objective sense (which it might, as you pointed out). That's a different question.

Does that make sense?


LearnEnglish team

Hi Jonathan!
I did the same interpretation as Iñaki. I think that a scientist will never ensure that there is no danger if he really does not have all the possible evidence.

Hi Ramiro Solana,

Note that the question does not say "there is no danger" - that's a different question.

I think it is reasonable to say that "Earth does not appear to be in any danger". In other words, the question is asking whether any signs of danger are currently apparent (they are not). The key word in the question is "appear", which means it's based on the evidence that is currently available.

To answer "False" here, the text would need to show danger signs and clearly contradict the question. It would need to say that "Earth does appear to be in danger". However, since the 50 remaining asteroids left to log may or may not be dangerous, the most that we could say is that they are potential (rather than actual) dangers.

It's a tricky question and I can see why you gave that answer, though.


LearnEnglish team

Submitted by JulyV1501 on Sat, 07/01/2023 - 23:31


Assuming that the asteroid is big and close enough to bring about a devastating impact that can affect the whole planet but it still takes some time to finally hit it, my choice depends on the situation, as an earlier comment said (by Lollipop). If I were far away from my parents and relatives, I would find a way to get where they are and share my remaining lifetime with them. I would also remember all the moments we lived together. Another goofy thing I'd do is to tell my crush that I've been in love with her since I knew her by WhatsApp. Despite it's the worst moment of my life, it's somehow one of the best ones since we don't care anymore about meaningless things but staying with the people who accompanied us almost all of our lives.