14-17 Which paragraph contains the following information?
- Examples of different ways in which the parallax principle has been applied
Keywords: examples, parallax principle
In paragraph F, the writer indicates that “Johann Franz Encke, Director of the Berlin Observatory, finally determined a value for the AU based on all these parallax measurements: 153,340,000 km….The AU is a cosmic measuring rod, and the basis of how we scale the Universe today. The parallax principle can be extended to measure the distances to the stars.” So, the parallax principle has been applied to determine a value for the AU and to measure the distances to the stars.
- a description of an event which prevented a transit observation.
Keywords: event, prevented transit observation
In paragraph D, the writer says that “He was thwarted by the fact that the British were besieging his observation site at Pondicherry in India. Fleeing on a French warship crossing the Indian Ocean, Le Gentil saw a wonderful transit – but the ship‟s pitching and rollingruled out any attempt at making accurate observations.”
– prevented=ruled out any attempt at
- a statement about potential future discoveries leading on from transit observations.
Keywords: future discoveries, transit observations.
In paragraph G, the writer indicates that “such transits have paved the way for what might prove to be one of the most vital breakthroughs in the cosmos – detecting Earth-sized planets orbiting other stars.”
– leading on from=paved the way for
- a description of physical states connected with Venus which early astronomical instruments failed to overcome.
Keywords: instruments, physical states, Venus, failed
In paragraph E, the writer argues that “While the early transit timings were as precise as instruments would allow, the measurements were dogged by the „black drop‟ effect. When Venus begins to cross the Sun‟s disc, it looks smeared not circular – which makes it difficult to establish timings. The second problem is that Venus exhibits a halo of light when it is seen just outside the Sun‟s disc. While this showed astronomers that Venus was surrounded by a thick layer of gases refracting sunlight around it, both effects made it impossible to obtain accurate timings.”
– physical states= the „black drop‟ effect, a halo of light
– failed to overcome=made it impossible
18-21 Match each statement with the correct person.
- He calculated the distance of the Sun from the Earth based on observations of Venus with a fair degree of accuracy.
Keywords: distance, observations of Venus, accuracy
In paragraph F, the writer indicates that “Johann Franz Encke, Director of the Berlin Observatory, finally determined a value for the AUbased on all these parallax measurements: 153,340,000 km. Reasonably accurate for the time, that is quite close to today‟s value of 149,597,870 km.”
– the distance of the Sun from the Earth=the AU
– with a fair degree of accuracy=reasonably accurate
- He understood that the distance of the Sun from the Earth could be worked out by comparing observations of a transit.
Keywords: distance, worked out bycomparing observations
In paragraph B, “He (Edmond Halley) realised that from different latitudes, the passage of the planet across the Sun‟s disc would appear to differ. By timing the transit from two widely-separated locations, teams of astronomers could calculate the parallax angle – the apparent difference in position of an astronomical body due to a difference in the observer‟s position. Calculating this angle would allow astronomers to measure what was then the ultimate goal: the distance of the Earth from the Sun.”
– work out=calculate, measure
- He realised that the time taken by a planet to go around the Sun depends on its distance from the Sun.
Keywords: time, around the Sun, distance from the Sun
In paragraph C, the writer argues that “Johannes Kepler, in the early 17th century, had shown that the distances of the planets from the Sungoverned their orbital speeds, which were easily measurable.”
– go around = orbit (orbital)
- He witnessed a Venus transit but was unable to make any calculations.
Keywords: Venus transit, unable, calculations
In paragraph D, “Fleeing on a French warship crossing the Indian Ocean, Le Gentil saw a wonderful transit – but the ship‟s pitching and rolling ruled out any attempt at making accurate observations”.
– unable=ruled out
– make any calculations=making accurate observations
- Halley observed one transit of the planet Venus.
Keywords: Halley, transit, Venus
In paragraph B, the writer indicates that “In November 1677, Halley observed a transit of the innermost planet, Mercury, from the desolate island of St Helena in the South Pacific…..Nevertheless, he accurately predicted that Venus would cross the face of the Sun in both 1761 and 1769 – though he didn‟t survive to see either”.
- Le Gentil managed to observe a second Venus transit.
Keywords: managed, second Venus transit.
In paragraph D, the writer states that “Undaunted, he remained south of the equator ….before setting off to observe the next transit in the Philippines. Ironically, after traveling nearly 50,000 kilometers, his view was clouded out at the last moment, a very dispiriting experience. ” This means that Le Gentil did not succeed in observing a second Venus transit in the Philippines.
- The shape of Venus appears distorted when it starts to pass in front of the Sun.
Keywords: shape, distorted, pass in front of the sun
In paragraph E, the writer says that “While the early transit timings were as precise as instruments would allow, the measurements were dogged by the „black drop‟ effect. When Venus begins to cross the Sun‟s disc, it looks smeared not circular.”
– pass in front of the Sun=cross the Sun‟s disc
– distorted=smeared not circular
- Early astronomers suspected that the atmosphere on Venus was toxic.
Keywords: atmosphere on Venus, toxic
In this passage, Venus‟s atmosphere is not mentioned by the writer, so it is not known whether it is toxic or not. Therefore, the statement is NOT GIVEN.
=>ANSWER: NOT GIVEN
- The parallax principle allows astronomers to work out how far away distant stars are from the Earth.
Keywords: parallax principle, how far, stars, Earth
In paragraph F, “The parallax principle can be extended to measure the distances to the stars. If we look at a star in January – when Earth is at one point in its orbit – it will seem to be in a different position from where it appears six month later. Knowing the width of Earth‟s orbit, the parallax shift lets astronomers calculate the distance.”