Read the following passage carefully and answer the questions given below it. Certain words have been highlighted for your attention.

Scientists using NASA’s Hubble Space Telescope have for the first time precisely measured the distance to one of the oldest objects in the universe, a 13.4 billion-year-old cluster of stars born shortly after the Big Bang. The refined distance yardstick provides an independent estimate for the age of the universe. It will also help astronomers improve models of stellar evolution. Star clusters are the key ingredient in stellar models because the stars in each grouping are at the same distance, have the same age, and have the same chemical composition. They, therefore, constitute a single stellar population to study.

This stellar assembly, a globular star cluster called NGC 6397, is one of the closest such clusters to Earth. The new measurement sets the cluster’s distance at 7,800 light-years away, with just a three percent margin of error. Until now, astronomers have estimated the distances to our galaxy’s globular clusters by comparing the luminosities and colours of stars to theoretical models, and to the luminosities and colours of similar stars in the solar neighbourhood.

However, the accuracy of these estimates varies, with uncertainties hovering between 10 percent and 20 percent. The new measurement uses straightforward trigonometry, the same method used by surveyors, and as old as ancient Greek science. Using a novel observational technique to measure extraordinarily tiny angles on the sky, astronomers managed to stretch Hubble’s yardstick outside of the disk of our Milky Way galaxy.