NASA has announced a major milestone in the search for planets beyond our solar system: the confirmation of 5,445 exoplanets.
This number includes planets detected by various methods, such as the transit method, the radial velocity method, and direct imaging. Among these exoplanets are some that resemble Earth in size and composition, some that orbit multiple stars, and some that have extreme conditions that challenge our imagination.
One of the most successful tools for finding exoplanets is NASA’s Kepler space telescope, which has discovered more than 2,600 planets by observing tiny dips in the brightness of stars as planets pass in front of them.
Kepler has also identified thousands of more candidates that await confirmation by other methods. Kepler’s mission ended in 2018, but its legacy lives on in the data it collected and the discoveries it enabled.
Another powerful instrument for exoplanet hunting is NASA’s Transiting Exoplanet Survey Satellite (TESS), which launched in 2018 and is surveying almost the entire sky for nearby planets. TESS has already found more than 100 confirmed planets and over 2,000 candidates.
TESS also provides valuable data for follow-up observations by other telescopes, such as NASA’s James Webb Space Telescope, which will launch later this year and will be able to study the atmospheres of some exoplanets in detail.
The diversity of exoplanets is astounding. Some are smaller than Earth, while others are larger than Jupiter. Some are rocky, while others are gaseous or icy. Some are scorching hot, while others are freezing cold.
Some are close to their stars, while others are far away. Some have exotic features, such as rings, moons, or oceans of lava.
One of the main goals of exoplanet exploration is to find planets that could potentially support life. Scientists look for planets that are in the habitable zone of their stars, meaning that they receive enough sunlight to allow liquid water on their surfaces.
They also look for signs of biosignatures, such as oxygen or methane, in the atmospheres of exoplanets. So far, no definitive evidence of life has been found on any exoplanet, but the search continues.
