ExoMoons Archives

June 30, 2024July 5, 2024 by Laurence Tognetti

Exomoons: Why study them? What can they teach us about finding life beyond Earth?

Artist's depiction of an exomoon orbiting a gas giant within the star's habitable zone. (Credit: NASA/JPL-Caltech)

Universe Today has had the recent privilege of investigating a multitude of scientific disciplines, including impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics, cosmochemistry, meteorites, radio astronomy, extremophiles, organic chemistry, black holes, cryovolcanism, planetary protection, dark matter, supernovae, and neutron stars, and how they both individually and collectively contribute to our greater understanding of our place in the universe.

Here, Universe Today discusses the growing field of exomoons with Dr. David Kipping, who is an assistant professor in the Astronomy Department at Columbia University, along with his PhD students, Benjamin Cassese and Daniel Yahalomi, regarding the importance of studying exomoons, the benefits and challenges, potential exomoon candidates, how exomoons can teach us about finding life beyond Earth, and advice for upcoming students who wish to pursue studying exomoons. Therefore, what is the importance of studying exomoons?

June 19, 2024June 19, 2024 by Evan Gough

If We Want To Find Life-Supporting Worlds, We Should Focus on Small Planets With Large Moons

A rocky planet with a large moon may have good potential to host life, given that the Moon controls essential aspects for life on Earth, including the length of the day, ocean tides, and stable climate. Image Credit: University of Rochester photo illustration by Michael Osadciw featuring Unsplash photography from Brad Fickeisen, Jaanus Jagomagi, and Engin Akyurt

There’s no perfect way of doing anything, including searching for exoplanets. Every planet-hunting method has some type of bias. We’ve found most exoplanets using the transit method, which is biased toward larger planets. Larger planets closer to their stars block more light, meaning we detect large planets transiting in front of their stars more readily than we detect small ones.

That’s a problem because some research says that life-supporting planets are more likely to be small, like Earth. It’s all because of moons and streaming instability.

May 21, 2024May 21, 2024 by David Dickinson

The Habitable Worlds Observatory Could See Lunar and Solar ‘Exo-Eclipses’

A future space observatory could use exo-eclipses to tease out exomoon populations.

If you’re like us, you’re still coming down from the celestial euphoria that was last month’s total solar eclipse. The spectacle of the Moon blocking out the Sun has also provided astronomers with unique scientific opportunities in the past, from the discovery of helium to proof for general relativity. Now, eclipses in remote exoplanetary systems could aid in the hunt for elusive exomoons.

January 29, 2024January 30, 2024 by Evan Gough

Did We Find Exomoons or Not? The Question Lingers.

Does Kepler-1708b have an exomoon? Scientists disagree. Image Credit: NASA

Do exoplanets have exomoons? It would be extraordinary if they didn’t, but as with all things, we don’t know until we know. Astronomers thought they may have found exomoons several years ago around two exoplanets: Kepler-1625b and Kepler-1708b. Did they?

January 13, 2024January 14, 2024 by Laurence Tognetti

Big Planets Don’t Necessarily Mean Big Moons

Artist's illustration of a large exomoon orbiting a large exoplanet. (Credit: NASA/ESA/L. Hustak)

Does the size of an exomoon help determine if life could form on an exoplanet it’s orbiting? This is something a February 2022 study published in Nature Communications hopes to address as a team of researchers investigated the potential for large exomoons to form around large exoplanets (Earth-sized and larger) like how our Moon was formed around the Earth. Despite this study being published almost two years ago, its findings still hold strong regarding the search for exomoons, as astronomers have yet to confirm the existence of any exomoons anywhere in the cosmos. But why is it so important to better understand the potential for large exomoons orbiting large exoplanets?

December 11, 2023December 11, 2023 by Evan Gough

Exomoons Defy Discovery

So far we only know of two exoplanets with candidate exomoons. But even those two may be false positives. Image Credit: NASA

For a long time, we wondered if other stars hosted planets like the Sun does. Finally, in the 1990s, we got our answer. Now, another question lingers.

Most of the planets in our Solar System have moons. Do exoplanets have exomoons?

March 28, 2023March 28, 2023 by Matt Williams

Moons Orbiting Rogue Planets Could be Habitable

An artist's conception of a potentially-habitable exomoon. Credit: NASA

When looking for signs of life beyond the Solar System, astrobiologists are confined to looking for life as we understand it. For the most part, that means looking for rocky planets that orbit within their star’s circumsolar habitable zone (HZ), the distance at which liquid water can exist on its surface. In the coming years, next-generation telescopes and instruments will allow astronomers to characterize exoplanet atmospheres like never before. When that happens, they will look for the chemical signatures we associate with life, like nitrogen, oxygen, carbon dioxide, methane, and ammonia.

However, astrobiologists have theorized that life could exist in the outer Solar System beneath the surfaces of icy moons like Europa, Callisto, Titan, and other “Ocean Worlds.” Because of this, there is no shortage of astrobiologists who think that the search for extraterrestrial life should include exomoons, including those that orbit free-floating planets (FFPs). In a recent study, researchers led by the Max Planck Institute for Extraterrestrial Physics (MPE) determined the necessary properties that allow moons orbiting FFPs to retain enough liquid water to support life.

August 18, 2022August 18, 2022 by Laurence Tognetti

What is the Maximum Number of Moons that Earth Could Have?

In a recent study published in Earth and Planetary Astrophysics, a team of researchers from the University of Texas at Arlington, Valdosta State University, Georgia Institute of Technology, and the National Radio Astronomy Observatory estimated how many moons could theoretically orbit the Earth while maintaining present conditions such as orbital stability. This study opens the potential for better understanding planetary formation processes which could also be applied to identifying exomoons possibly orbiting Earth-like exoplanets, as well.

May 11, 2022May 11, 2022 by Evan Gough

These are the Best Places to Search for Habitable Exomoons

Our Solar System contains eight planets and more than 200 moons. The large majority of those moons have no chance of being habitable, but some of them—Europa and Enceladus, for example—are strong candidates in the search for life.

Is it the same in other solar systems?

February 8, 2022February 8, 2022 by Evan Gough

Massive Rocky Planets Probably Don’t Have big Moons

The Earth straddling the limb of the Moon, as seen from above Compton crater on the lunar farside, taken by the Lunar Reconnaissance Orbiter spacecraft. Credit: NASA/GSFC/Arizona State University.

The Moon has orbited Earth since the Solar System’s early days. Anyone who’s ever spent time at the ocean can’t fail to notice the Moon’s effect. The Moon drives the tides even in the world’s most remote inlets and bays. And tides may be vital to life’s emergence.

But if Earth were more massive, the Moon may never have become what it is now. Instead, it would be much smaller. Tides would be much weaker, and life may not have emerged the way it did.