Exoplanet K2-18b

[ThatOwlWoman]

Anyone want to guess what's wrong with this picture?

Retrograde spin?

 

[Dutch Uncle]

Retrograde spin?

Yes. I was looking for a world turning gif and saw that one. A others had the Earth rotating in the wrong direction too.

 

[Dutch Uncle]

Retrograde spin?

As the solar system coalesced, it began to spin and eventually everything began spinning in the same direction. IIRC, Mercury, like our own Moon, is basically gravity locked to facing the Sun; it rotates every 58 days but only takes 88 days to go around the Sun. Something knocked Uranus over so it's spinning almost 100 degrees off from the other planets, but its orbit remains counterclockwise like all other planets.

https://solarsystem.nasa.gov/planets/mercury/in-depth/

Mercury's highly eccentric, egg-shaped orbit takes the planet as close as 29 million miles (47 million kilometers) and as far as 43 million miles (70 million kilometers) from the Sun. It speeds around the Sun every 88 days, traveling through space at nearly 29 miles (47 kilometers) per second, faster than any other planet.

Mercury spins slowly on its axis and completes one rotation every 59 Earth days. But when Mercury is moving fastest in its elliptical orbit around the Sun (and it is closest to the Sun), each rotation is not accompanied by sunrise and sunset like it is on most other planets. The morning Sun appears to rise briefly, set, and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset for other parts of the surface. One Mercury solar day (one full day-night cycle) equals 176 Earth days – just over two years on Mercury.

 

[Cypress]

As the solar system coalesced, it began to spin and eventually everything began spinning in the same direction. IIRC, Mercury, like our own Moon, is basically gravity locked to facing the Sun; it rotates every 58 days but only takes 88 days to go around the Sun. Something knocked Uranus over so it's spinning almost 100 degrees off from the other planets, but its orbit remains counterclockwise like all other planets.

https://solarsystem.nasa.gov/planets/mercury/in-depth/

I think Venus is an outlier in that it rotates in the opposite direct to the rest of the planets. I don't remember why, but vaguely recall maybe Venus had a massive collision with a planetoid billions of years ago.

 

[Dutch Uncle]

I think Venus is an outlier in that it rotates in the opposite direct to the rest of the planets. I don't remember why, but vaguely recall maybe Venus had a massive collision with a planetoid billions of years ago.

Good point. The NASA website doesn't explain why Venus rotates so slowly or in retrograde manner, but, from what I can understand, the Wiki link says it's a combination of the Sun's gravity and the dense Venusian atmosphere over the course of a billion years+ that have slowed the planet's rotation and started it moving in the opposite direction, albeit very slowly.

https://en.wikipedia.org/wiki/Venus#Orbit_and_rotation
All planets in the Solar System orbit the Sun in an anticlockwise direction as viewed from above Earth's north pole. Most planets rotate on their axes in an anticlockwise direction, but Venus rotates clockwise in retrograde rotation once every 243 Earth days—the slowest rotation of any planet. This Venusian sidereal day lasts therefore longer than a Venusian year (243 versus 224.7 Earth days).

https://solarsystem.nasa.gov/planets/venus/in-depth/
Spending a day on Venus would be quite a disorienting experience – that is, if your ship or suit could protect you from temperatures in the range of 900 degrees Fahrenheit (475 Celsius). For one thing, your “day” would be 243 Earth days long – longer even than a Venus year (one trip around the Sun), which takes only 225 Earth days. For another, because of the planet's extremely slow rotation, sunrise to sunset would take 117 Earth days. And by the way, the Sun would rise in the west and set in the east, because Venus spins backward compared to Earth.

 

[Cypress]

 

[Dutch Uncle]

https://cdn.esawebb.org/archives/images/screen/weic2321b.jpg

What kind of life would exist in that atmosphere? The anaerobic life previously discussed?

 

[Cypress]

What kind of life would exist in that atmosphere? The anaerobic life previously discussed?

I'm not an expert and haven't read what the exobiologists say. But the absence of free oxygen in the atmosphere would likely indicate an absence of photosynthesis, and an associated biosphere that requires O[sub]2[/sub] for respiration.

That leaves you with chemosynthesis, or some other anerobic process for energy and metabolism.

 

[Saint Guinefort]

I'm not an expert and haven't read what the exobiologists say. But the absence of free oxygen in the atmosphere would likely indicate an absence of photosynthesis, and an associated biosphere that requires O[sub]2[/sub] for respiration.

That leaves you with chemosynthesis, or some other anerobic process for energy and metabolism.

Ironically enough dimethyl sulfide is produced by PHYTOPLANKTON. That indicates photosynthesis must be happening at some level. Where is the O2?

 

[Dutch Uncle]

Ironically enough dimethyl sulfide is produced by PHYTOPLANKTON. That indicates photosynthesis must be happening at some level. Where is the O2?

Is that the sole source of naturally occurring DMS?

 

[Saint Guinefort]

Is that the sole source of naturally occurring DMS?

"Marine phytoplankton are the primary source of dimethylsulfide (DMS)"
Plankton And Climate
P.C. Reid, M. Edwards, in Encyclopedia of Ocean Sciences, 2001

 

[Dutch Uncle]

"Marine phytoplankton are the primary source of dimethylsulfide (DMS)"
Plankton And Climate
P.C. Reid, M. Edwards, in Encyclopedia of Ocean Sciences, 2001

Primary doesn't equal sole.

Still, the presence of DMS on K2 18B is a curious phenomenon. How do you explain it?

 

[Saint Guinefort]

Primary doesn't equal sole.

Still, the presence of DMS on K2 18B is a curious phenomenon. How do you explain it?

Fair point. I honestly don't know. On the NASA page they note that "On Earth, this [DMS] is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments." (SOURCE)

I'm guessing there might be some other means of production of DMS that is possible, maybe even a non-life source? It's curious.

 

[Dutch Uncle]

Fair point. I honestly don't know. On the NASA page they note that "On Earth, this [DMS] is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments." (SOURCE)

I'm guessing there might be some other means of production of DMS that is possible, maybe even a non-life source? It's curious.

I'm certain NASA will take a look at it again over time to verify the results.

 

[Cypress]

I'm certain NASA will take a look at it again over time to verify the results.

Like I wrote earlier, NASA is not jumping to any conclusions. They are practicing good, objective science and intend to do a lot more confirmation and validation.

 

[Dutch Uncle]

Like I wrote earlier, NASA is not jumping to any conclusions. They are practicing good, objective science and intend to do a lot more confirmation and validation.

Agreed. Also mentioned earlier is that NASA reports facts and the media seeks to make money. The dumbasses in our society do not understand the difference and, therefore, blame science.

 

[Cypress]

Agreed. Also mentioned earlier is that NASA reports facts and the media seeks to make money. The dumbasses in our society do not understand the difference and, therefore, blame science.

Trumpeting DSM as evidence of alien life your tabloid headline is good clickbait.

 

[Dutch Uncle]

Trumpeting DSM as evidence of alien life your tabloid headline is good clickbait.

Agreed on both clickbait and tabloid fodder. Finding DMS is an interesting find, but, as you've mentioned previously, assuming things across the universe are the same as on Earth is a risky assumption.