Comparing young and old exoplanets helps astronomers understand how planets form, evolve, and change over time.
Young exoplanets provide a window into their primordial state. Through the detection of tiny drops in sunlight as planets pass in front of their stars, NASA's Kepler and TESS missions allow scientists to see exoplanets at various phases of life.
Young planets orbit young stars, which are often highly active and produce noisy signals. This makes it difficult to extract planetary data. Advanced techniques are needed to detect signals amid stellar activity.
Studies of planets with short orbits (less than 12 days) reveal two major evolutionary trends. First, planets shrink as they lose atmospheres, and second, they migrate inward due to interactions with their star. Understanding these processes could help explain planetary evolution.
Researchers categorized exoplanets into two groups: young (10–100 million years) and intermediate-age (100 million–1 billion years). Data from TESS and Kepler suggest a higher occurrence of young planets, indicating that many planets shrink over time as they lose their atmospheres.
Close orbiting planets are exposed to intense stellar radiation, which strips away their atmospheres. Over hundreds of millions of years, this causes planets to shrink. This phenomenon, occurring over the period of hundreds of years causes shrinking of planets.
A process called tidal migration pulls planets closer to their stars over time. This gradual inward movement affects planetary orbits and could help explain why some planets are found in extremely short orbits.
Upcoming NASA and ESA missions, including Roman, PLATO, and Gaia, will significantly increase the number of known exoplanets. These observations will provide a more complete picture of planetary formation and evolution.