How did hitting an asteroid’s moon change the pair’s orbit around the Sun?

Check your understanding

15-question test

Answer all the questions, then check your results.

1. True / False

   1.The approximately 33-minute reduction describes the asteroid pair’s orbital period around the Sun.

   ATrueBFalse
2. 2.The spacecraft’s incoming momentum alone accounts for the full deflection; the expelled debris made no additional contribution.

   ATrueBFalse
3. 3.Hera is intended to investigate the impact outcome as well as measure Dimorphos’s physical properties.

   ATrueBFalse

4. Reading Comprehension

   4.Why can an impact on Dimorphos affect the motion of the asteroid pair?

   AThe impact removes the Sun’s gravitational influence on Didymos.BThe asteroids are gravitationally linked and orbit a shared centre of mass.CThe debris makes the asteroids move independently of each other.DThe spacecraft must strike both asteroids for either orbit to change.
5. 5.What made the debris plume more than a visible aftermath of the collision?

   AIt established the exact composition of Dimorphos.BIt showed that the spacecraft had struck Didymos directly.CIts escaping material carried momentum away and produced additional recoil.DIt eliminated the need to investigate the impact site.
6. 6.Inference: What should scientists avoid assuming when considering a similar impact on a different asteroid?

   AThat the asteroid’s physical properties could influence its response.BThat investigating Dimorphos could improve their understanding.CThat expelled debris could contribute to momentum transfer.DThat an identical collision would necessarily produce an equally effective result.

7. Grammar & Phrasal Verbs

   7.Which sentence would sound most natural in professional English?

   AHera is intended measuring the asteroid’s physical properties.BHera is intended to measure the asteroid’s physical properties.CHera is intended to the measurement the asteroid’s physical properties.DHera is intended for measure the asteroid’s physical properties.
8. 8.Which reformulation best preserves the meaning of “not merely what hit it”?

   AScientists should consider both what left the asteroid and what hit it.BScientists should consider what hit the asteroid instead of what left it.CScientists should consider what left the asteroid only if nothing hit it.DScientists should consider neither the incoming craft nor the escaping material.
9. 9.Which sentence best preserves the meaning of “This is where Hera comes into the picture”?

   AThis is where Hera supplies a photograph.BThis is where Hera’s work is already complete.CThis is the point at which Hera becomes relevant.DThis is where Hera becomes less relevant.

10. Prepositions

    10.Complete the sentence: “An asteroid’s response depends ___ its physical properties.”

    AtoBwithConDfrom
11. 11.Complete the sentence: “The expelled material increased the deflection ___ the spacecraft’s direct contribution.”

    AbeyondBamongCwithinDbeneath
12. 12.Complete the sentence: “As debris carried momentum away, the remaining asteroid recoiled ___ response.”

    AatBbyConDin

13. Vocabulary & Synonyms

    13.What does “recoil” mean in the explanation of the impact?

    AA reactive movement caused by material being expelled.BThe gradual disappearance of the debris.CThe attraction holding the asteroid pair together.DThe spacecraft’s approach before the collision.
14. 14.Which phrase is closest in meaning to “deflection” as used in the article?

    AA measurement of composition.BA change of course.CA complete loss of mass.DA return to the original position.
15. 15.What does “a successful experiment is not a universal recipe” mean here?

    AA successful experiment cannot provide useful evidence.BEvery asteroid should be studied using an identical procedure.CThe experiment’s outcome depends only on the spacecraft, not the asteroid.DSuccess in this case does not establish a method that works equally well in every case.