IELTS ACADEMIC READING TEST
Jupiter’s Bruises
(In 1994 the comet Shoemaker-Levy 9 collided with the planet Jupiter, causing great excitement in the world of astronomy. The article which follows was written after the first impact.)
Shoemaker-Levy 9 has plunged into Jupiter, and the Hubble Space Telescope has moved away to look at other objects in space. Amateur astronomers, however, are still watching Jupiter to see what bruises were left on the mighty planet by the comet crash of 1994. There was tremendous excitement in astronomical circles during the collision of comet and planet. It is now time to see what has been learned from this impact.
One question which may never be answered: Was Shoemaker-Levy 9 really a comet, or was it an asteroid instead ? Comets tend to be a mixture of ice, rock and dust, along with other substances, like carbon monoxide, that evaporate quickly to form a halo and a tail. Scientists studying the chemical composition of the spots on Jupiter where Shoemaker Levy 9 (S-L 9) hit thought they might see evidence of water and oxygen, two of the expected products when an icy comet vaporises. But except for one unconfirmed report, researchers have found only ammonia, hydrogen sulphide and sulphur gas.
Asteroids are rockier than comets. Yet it is possible for an asteroid to have a halo or a tail, made mostly of dust. Says Hal Weaver of the Space Telescope Institute: ‘The only real evidence that SL-9 was a comet is that it broke apart, and we’ve never seen that in an asteroid. But maybe this was a fragile asteroid’.
Amateur astronomer David Levy, who with Eugene and Carolyn Shoemaker discovered SL-9, points out that comets were originally distinguished by their appearance. They are objects that look like fuzzy stars with tails, and in any previous century astronomers would have called this discovery a comet. On that basis, argues Levy, ‘S-L 9 is a comet, period’.
The apparent absence of water at the impact sites provides a clue about how far the SL-9 fragments penetrated Jupiter’s atmosphere before exploding. Theorists think that a layer of water vapour lies some 95 km below the visible cloud tops; above the vapour layer, about 50 km down, are clouds believed to consist of a sulphur compound. Since no water seems to have been stirred up, the explosion probably took place in the presumed sulphide layer.
If researchers confirm that the sulphur rose up from Jupiter, it will be ‘a major discovery,’ says University of Arizona astronomer Roger Yelle. ‘We’ve always believed that much of the colour in Jupiter’s clouds comes from sulphur compounds, but we’ve never detected them.’
No one knows why the points of impact are so dark, but it is clear that they are very high up in Jupiter’s atmosphere, since the planet’s stripes can be seen through them. Astronomers believe the collisions will provide an opportunity to study the winds above Jupiter’s cloud tops. The mark left by the first impact is already starting to be spread around. There are also hints of seismic waves – ripples that may have travelled all the way to a dense layer of liquid hydrogen thousands of kilometers down and then bounced back up to the surface, creating rings half the size of the planet’s visible face. These waves may offer clues to Jupiter’s internal structure.
The spots that were made by the collision will undoubtedly blow away eventually, but it’s much too soon to tell if there will be any permanent changes in Jupiter. There is still every chance that the impacts, especially from the four fragments that hit in nearly the same place, will destabilise the atmosphere and create a new, permanent cyclone like Jupiter’s Great Red Spot.
It’s also possible that the show isn’t quite over. Theorists using a computer model argue that debris has lagged behind the original 21 major fragments. These stragglers, they predict, will keep hitting Jupiter for months to come. Unlike the previous fragments the latecomer will smash into the near side of the planet, giving astronomers a chance to watch some strikes directly. Is the theory plausible? Says one astronomer, ‘We’ve had so many surprises from S-L 9 already that I wouldn’t rule anything out’.Questions 1 – 7
Choose TRUE if the statement agrees with the information given in the text, choose FALSE if the statement contradicts the information, or choose NOT GIVEN if there is no information on this.
1Evidence so far indicates that further study of shoemaker- Levy 9 will be worthwhile.
- TRUE
- FALSE
- NOT GIVEN
2There are no physical differences between asteroids and comets.
- TRUE
- FALSE
- NOT GIVEN
3The observation of shoemaker-Levy 9 was an immensely expensive undertaking.
- TRUE
- FALSE
- NOT GIVEN
4David Levy, being an amateur astronomer, was not taken seriously.
- TRUE
- FALSE
- NOT GIVEN
5The dark points of impact intricate there is water on Jupiter.
- TRUE
- FALSE
- NOT GIVEN
6Researchers confirmed that the sulphur rose up from Jupiter.
- TRUE
- FALSE
- NOT GIVEN
7It is now possible to perform detailed studies of Jupiter’s internal structure.
- TRUE
- FALSE
- NOT GIVEN
8It is possible that comets can destabilize Jupiter’s atmosphere permanently.
- TRUE
- FALSE
- NOT GIVEN
9It is possible that more impacts have occurred since article was written.
- TRUE
- FALSE
- NOT GIVEN
Questions 10 – 14
Complete the summary below. Choose no more than THREE WORDS AND/OR NUMBERS from the passage and write them in boxes 10 – 14.
The comet observed using the (10)
A comet’s tail is usually made up of substances that evaporate quickly such as (11)
Researchers had expected to see evidence of (12) at the impact site, showing the comet’s composition.
The presence of sculpture compounds may account for the (13) of Jupiter’s clouds.
The destabilized atmosphere may lead to the formation of another permanent (14) on Jupiter.