Pandora: searching exomoons.

 Pandora: searching exomoons. 

When we make models of another solar system, we use our solar system as a model. That means the gas giants should have moons because most of the planets in our solar system have moons. But we have not yet seen one. The reason for that is that those exoplanets, like gas giants, can be so massive that small moons cannot cause anomalies in their trajectories. And most of the exomoons should be quite small objects. 

If some large, about Earth-size moon, orbits some massive planet or brown dwarf and the system will not make over overpass between its star and Earth, and the moon doesn't travel between its planet or brown dwarf and Earth those kinds of moons are hard to detect. And if that moon orbits bright stars like G-2 or Sun-type stars it's even harder to see. The star's brightness will not decrease if a small planet travels between it and Earth. Also normal stellar activity, like starspots, can cause changes in the star's brightness. 

This artist’s impression shows a gas giant exoplanet orbiting a sun-like star, exemplified by Kepler-1625b. Credit: NASA (ScitechDaily.com/Pandora’s Box of Cosmic Mysteries: Rethinking Giant Exomoons)

"Several influences can create a moon-like signal in a light curve – even without the presence of an actual moon. Credit: MPS/hormesdesign.de" (ScitechDaily.com/Pandora’s Box of Cosmic Mysteries: Rethinking Giant Exomoons)

"Research reveals that giant gas planets in other star systems often make their Earth-like neighbors uninhabitable by disrupting orbits and climates. Unlike Jupiter’s protective role in our solar system, these planets frequently prevent the development of stable, life-supporting conditions, highlighting the exceptional nature of our planetary configuration. Artist’s depiction of an extra-solar system that is crowded with giant planets. Credit: NASA/Dana Berry." (ScitechDaily.com/Chaos Reigns in the Cosmos: How Giant Gas Planets Threaten Life on Nearby Earth-Like Worlds)

Large gas giants can also endanger lifeforms in exoplanet systems. Large and massive exoplanets pull objects to them. And especially in young solar systems cosmic impacts can strip atmospheres off the planets. Also in more mature systems gas giants pull comets and asteroids to them. And the main question is can the large moon host lifeforms? 

The risk of cosmic impacts is higher near large and massive exoplanets. That thing can cause possible lifeforms can form later on those moons. But otherwise, we can say that Titan has also an atmosphere, and we have not seen any devastating impacts with asteroids and Titan. 

We know that in the past that kind of impact destroyed many protoplanets in the chaotic young solar system. One of those impacts, Earth's impact with a large asteroid or protoplanet Theia almost destroyed Earth. Remnants of that impact still exist in Earth's Magma. Also if the exomoon is too close to its giant planet, that planet can strip off its moon's atmosphere. 

But otherwise, the exomoons can have bigger tidal water. And that means they can be good places for life forms and evolution. But there is a possibility that those tidal forces lock the moon to its planet. That means the hypothetical exomoon would always turn the same side to its planet. In that case, the day on that exomoon lasts the same time as its orbiting time. 

Does the planet lock its moon? That depends on the distance of the moon from its planet. In some models. That moon would travel through the planet's shadow. But the moon can have a polar trajectory that can make it possible for an exomoon's rotation time around its axle could be 24 hours. The distance to the exoplanet determines does the moon locks. 

https://scitechdaily.com/chaos-reigns-in-the-cosmos-how-giant-gas-planets-threaten-life-on-nearby-earth-like-worlds/

https://scitechdaily.com/pandoras-box-of-cosmic-mysteries-rethinking-giant-exomoons/