Practice Tests
IELTS Reading (AC) Task 1 #174

A. An exoplanet is any planet that orbits a star outside of our solar system. For centuries, the existence of such worlds was purely a matter of speculation, but the first confirmed discovery of an exoplanet in the 1990s opened up a new and exciting field of astronomy. Since then, thousands of exoplanets have been discovered, revealing a stunning diversity of worlds, from massive "hot Jupiters" orbiting incredibly close to their stars to small, rocky planets that might be similar to Earth.

B. The two most successful methods for detecting exoplanets are the transit method and the radial velocity method. The transit method, used by space telescopes like NASA''s Kepler and TESS, looks for tiny, periodic dips in a star''s brightness. This dimming can indicate that a planet is passing in front of the star from our point of view. The radial velocity method, or "wobble" method, detects the slight gravitational tug a planet exerts on its host star, causing the star to wobble back and forth. This wobble can be detected by measuring shifts in the star''s light spectrum.

C. The study of exoplanets is driven by some of the most fundamental questions in science: Are we alone in the universe? And could there be other planets capable of supporting life? By studying the size, mass, and orbit of an exoplanet, astronomers can begin to characterise its nature. A key focus is the search for planets located within the "habitable zone" of their star—the region where conditions might be just right for liquid water to exist on the planet''s surface, which is considered a crucial ingredient for life as we know it.

D. The next frontier in exoplanet research is to study their atmospheres. Using powerful instruments like the James Webb Space Telescope, astronomers can analyse the starlight that passes through an exoplanet''s atmosphere. This can reveal the presence of different gases, such as water vapour, methane, or oxygen, which could be potential biosignatures—indicators of life. While the discovery of an alien world teeming with life remains a distant goal, the ongoing search for and characterisation of exoplanets is fundamentally reshaping our understanding of our place in the cosmos.