Astronomers Have Found Another Possible 'Exomoon' beyond Our Solar System (scientificamerican.com) 10
Astronomers say they have found a second plausible candidate for a moon beyond our solar system, an exomoon, orbiting a world nearly 6,000 light-years from Earth. Scientific American reports: Called Kepler-1708 b-i, the moon appears to be a gas-dominated object, slightly smaller than Neptune, orbiting a Jupiter-sized planet around a sunlike star -- an unusual but not wholly unprecedented planet-moon configuration. The findings appear in Nature Astronomy. Confirming or refuting the result may not be immediately possible, but given the expected abundance of moons in our galaxy and beyond, it could further herald the tentative beginnings of an exciting new era of extrasolar astronomy -- one focused not on alien planets but on the natural satellites that orbit them and the possibilities of life therein.
Kepler-1708 b-i's existence was first hinted at in 2018, during an examination of archival data by David Kipping of Columbia University, one of the discoverers of Kepler-1625 b-i, and his colleagues. The team analyzed transit data from NASA's Kepler space telescope of 70 so-called cool giants -- gas giants, such as Jupiter and Saturn, that orbit relatively far from their stars, with years consisting of more than 400 Earth days. The team looked for signs of transiting exomoons orbiting these worlds, seeking additional dips in light from any shadowy lunar companions. Then the researchers spent the next few years killing their darlings, vetting one potential exomoon candidate after another and finding each better explained by other phenomena -- with a single exception: Kepler-1708 b-i. "It's a moon candidate we can't kill," Kipping says. "For four years we've tried to prove this thing was bogus. It passed every test we can imagine."
The magnitude of the relevant smaller, additional dip in light points to the existence of a moon about 2.6 times the size of Earth. The nature of the transit method means that only the radius of worlds can be directly gleaned, not their mass. But this one's size suggests a gas giant of some sort. "It's probably in the 'mini Neptune' category," Kipping says, referring to a type of world that, despite not existing in our solar system, is present in abundance around other stars. The planet this putative mini Neptune moon orbits, the Jupiter-sized Kepler-1708 b, completes an orbit of its star every 737 days at a distance 1.6 times that between Earth and the sun. Presuming the candidate is genuinely a moon, it would orbit the planet once every 4.6 Earth days, at a distance of more than 740,000 kilometers -- nearly twice the distance our own moon's orbit around Earth. The fact that only this single candidate emerged from the analysis of 70 cool giants could suggest that large gaseous moons are "not super common" in the cosmos [...].
Kepler-1708 b-i's existence was first hinted at in 2018, during an examination of archival data by David Kipping of Columbia University, one of the discoverers of Kepler-1625 b-i, and his colleagues. The team analyzed transit data from NASA's Kepler space telescope of 70 so-called cool giants -- gas giants, such as Jupiter and Saturn, that orbit relatively far from their stars, with years consisting of more than 400 Earth days. The team looked for signs of transiting exomoons orbiting these worlds, seeking additional dips in light from any shadowy lunar companions. Then the researchers spent the next few years killing their darlings, vetting one potential exomoon candidate after another and finding each better explained by other phenomena -- with a single exception: Kepler-1708 b-i. "It's a moon candidate we can't kill," Kipping says. "For four years we've tried to prove this thing was bogus. It passed every test we can imagine."
The magnitude of the relevant smaller, additional dip in light points to the existence of a moon about 2.6 times the size of Earth. The nature of the transit method means that only the radius of worlds can be directly gleaned, not their mass. But this one's size suggests a gas giant of some sort. "It's probably in the 'mini Neptune' category," Kipping says, referring to a type of world that, despite not existing in our solar system, is present in abundance around other stars. The planet this putative mini Neptune moon orbits, the Jupiter-sized Kepler-1708 b, completes an orbit of its star every 737 days at a distance 1.6 times that between Earth and the sun. Presuming the candidate is genuinely a moon, it would orbit the planet once every 4.6 Earth days, at a distance of more than 740,000 kilometers -- nearly twice the distance our own moon's orbit around Earth. The fact that only this single candidate emerged from the analysis of 70 cool giants could suggest that large gaseous moons are "not super common" in the cosmos [...].
"That's no moon" (Score:2)
No life (Score:1)
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No. The tidal lock occurs where the object is close to the parent object, so the difference of gravity on the closest side of the object and the farther side is enough different to generate a deformation in the object that turns into friction, heat and resonance in the end that creates the tidal lock.
In fact, although the radius of the moon is bigger is the object is more massive, the more mass also makes the object to have more inertia so it will take more time to reach the syncronization. It depends more
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The best and most common place for life may be within moons similar to Europa or Enceladus, or even dwarf planets like Pluto. There are tons of them, and they might be better than Earth for life, we just don't know yet.
Of course, those aren't places we'd expect technological or space-faring life (although the life could be intelligent).
Not exomoon, just moon (Score:3)
Using the "exo" for something just because it's outside our star system is a strange habit.
There's an entire universe outside our star system, and prefixing everything with "exo" will get old... Exostar? Exoquasar? Exogas? Exoasteroid? Exoplanet? Exomatter? Exolight? Exoplasma? Exo-orbit? Exogravity? It's all normal stuff, located outside our star system, and doesn't need a special prefix.
Contrast that with "exoskeleton" which actually means something -- a skeleton that is on the outside of a body instead of inside, regardless of where it is in the universe.
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Yes, it's the reason they do it, but it's not necessary if we already capitalize Sun, Earth, and Moon to refer to our home bodies. Even without capitalizing, it's usually clear from the context. The "exo" prefix here is redundant, a relic of geocentric and heliocentric thinking.
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Imagine a future where a person is standing on the surface of Mars. The person is looking at the earth beneath their feet. Oops, at the "mars" beneath their feet. Then the person looks up at their two exomoons, Phobos and Deimos. Or are they just moons when you're on Mars, and Earth's Moon is an exomoon?
They wouldn't be able to use the same astronomy textbooks because all the "exo" references would need to be reversed. This situation would be even worse when standing on an "exoplanet" such as Kepler 22b. L