cometary

However the source of the volatiles is not the type of chemistry that happened on early Earth, but rather cometary deposits and exospheric interactions.

So yes, the cometary nucleus hardly reflects any light, but some light is reflected by the coma and the tail.

It would take a lot of cometary impacts to seed the entire ocean with that much.

Currently visiting, this book orbits in and out of the rotation with a cometary periodicity.

I mearly responded with that option and didn't add any cometary on if it's a good idea or not.

So not even the experts know, yet, although cometary delivery in cyanide ices from comets is a leading hypothesis (similar to the delivery of water ices).

Additionally, protoplanet and cometary collisions are in fact statistically inevitable.

The complexity of cometary nucleus chemistry and the importance of N-containing organics imply that early solar system chemistry fosters the formation of prebiotic material in noticeable concentrations.

*Anomalous Tail* For several weeks, its tail *pointed toward the Sun*—the *opposite* of normal cometary behavior—before abruptly reversing direction.

Absence of cometary activity despite substantial non-gravitational acceleration.

It's also presumed that cometary ice bombardment is the source of Earth's surface water, as ice or water present any earlier would have boiled off when the planet was young and hot.

However, despite extensive observations by the Spitzer Space Telescope, no carbon-based molecules, dust, or thermal emission indicative of cometary outgassing were detected (Trilling et al., 2018).

Abstract: "The environs of other stellar systems may be directly probed by analyzing the cometary activity of interstellar objects.

TFA: “The power from the solar arrays is not sufficient, on its own, to drill and analyse cometary samples, for example.” Its clear that power is an issue and an RTG would have solved it.

So while this result lowers the plausibility of the proposition "Earth's water came from early cometary impacts" only a liar or a "science journalist" (but I repeat myself) would claim something completely and utterly false, like, "Scientists prove Earth's water not from comets!" Yet that is a headline I've actually seen on these results.

Cometary impact is considered the primary delivery method for water onto planets.

Cometary tails also only offgas a significant amount near the sun.