Water is common on exoplanets, but it's not as plentiful as expected

Scientists have discovered something strange about the exoplanets that have been discovered and studied so far. Water, which is essential for life as we know it, is said to be common, but unexpectedly scarce on exoplanets. What scientists have found is that many exoplanets have water, but there is less water on the distant worlds than expected.Scientists have studied data from the atmospheres of 19 exoplanets collected by space-based and ground-based telescopes. The worlds range in temperature from nearly 70 degrees F to more than 3,630 degrees F. The planets ranged in size from mini-Neptunes that are more than ten times Earth's mass to super-Jupiters that are more than 600 times Earth's mass.

The team found that water vapor was common on the alien worlds having been detected in 14 of the 19 worlds. The scientists note that it's easier to detect water vapor on exoplanets than in our solar system. Other than water, the chemicals most detected in giant exoplanet atmospheres were sodium and potassium with amounts consistent with expectations given what is known about planets in our solar system.

However, the scientists found significantly lower water vapor levels than predicted. Predictions for water on the exoplanets have been based on how much water gas giants in our solar system might contain. Water expectations were based on the amount of carbon relative to hydrogen in the atmospheres of gas planets.

The findings suggest that when giant planets form, less ice may fall into them than previously thought. The team says that if gas giants form by accreting material in a protoplanetary disk around the newborn star, they may accrete very different levels of chemicals, like water, depending on where they form and how the planets move in the protoplanetary disc. The team plans to continue researching the topic.