They’re unsure whether it’s from the planet or the star. Can’t they just check whether it’s from an ion of water or the stable molecule? (Which IIRC is a question of the spectra observed.) I remember from undergrad the chemistry in stars would often have pretty extreme ionizations like OH^-12. If it’s a high ionization and still on the planet that seems unlikely to be habitable as we know it (or something fleeting from a lightning strike).
Sorry I know this is low effort but "Can’t they just check" in the context of the James Webb Space Telescope and NASA operating it did make me chuckle. I'm pretty sure they checked :)
The planet is tidally locked to the star, so absent an atmosphere, the side of the planet facing away from the star will be freezing. If there is an atmosphere then the opposite side of the planet may be a bit more mild?
Actually if it’s tidally locked a lot of complications could be involved. If the backside of it managed to be hot it’d probably imply an atmosphere or young planet (guessing) or maybe a recent flip (see link). All just my naive thoughts.
Sure would be something if such planets could have atmospheres. That’d seem to imply a temperature gradient from the hot to cold side and would provide a mechanism for heat transfer.
I don’t think it’s an “industry term” in astronomy. I suspect it’s pretty much a given when discussing a planet that, unless the planet is referred to as Earth, it’s not Earth. And I suspect in the context of the JWST it’s pretty clear that it’s not Earth (does JWST ever look at Earth?).
JWST can't look at earth without major damage, as it is in a halo orbit around the Earth-Sun L2 point, which means pointing the optics (which are carefully protected from direct sunlight by that fancy five-layer sunshield) at Earth, also involves pointing those optics vaguely at the Sun.
We are for all purposes, the "ET" of others. Excluding creation by a Deity, Machine God or a Simulation, we are also the proof life can emerge in the Universe.
What most struck me from this article was this 'graph near the end:
Should GJ 486 b have a thin atmosphere or no atmosphere at all then the hottest region of its dayside should be directly under the red dwarf star. If this hottest point is offset, however, this could indicate the presence of an atmosphere that is thick enough to circulate heat.
Given that GJ 486 b is one-third the size of Earth, and orbits its star at one half of one percent the distance from Earth to the Sun, we can resolve where thermal intensity is highest on the planetary surface at a distance of 26 light years and despite the nearness of the star itself ... is pretty mind-blowing.
Can someone shed light on how names like 'GJ 486 b' are arrived at? Looks to me like something pulled out of a random number generator and piped through a base64 encoder or something like that, but surely there's a method to the madness?
Yeah there’s a lot of things we’ve normalized that are kinda silly from a zoomed out view.
“Okay so we have 12 months. About half are 30 days and the other half are 31 days but then ONE of them is 28 days except every fourth year that month with 28 days has a 29th day”
Calendrical idiosyncracies make far more sense when you realise that:
1. They refer to three distinct and largely independent phenomena: the rotation of the Earth about its axis (day, and subdivisions hours, minutes, and seconds), the orbit of the Moon around Earth (month, with caveats), and the orbit of Earth around the Sun (year). The fact that there is a rough days-based approximation of each is coincidental. Consider that on some planets there is no clear definition of a day (e.g., gas giants with no observable solid ground), or fixed rotational period (the duration of Venus's "day" apparently varies considerably under the influence of winds, and even Earth's day changes measurably due to tidal influences and factors).
2. Collective agreement and tradition are a real bear. It took nearly 500 years for the Gregorian Calendar to be universally adopted --- Russia's "October Revolution" occurred in what most of Europe considered to be November, as Russia had not yet adopted the Gregorian Calendar first introduced in October 1582. And it wasn't even the last country to do so! China's adoption of the Gregorian Calendar occurred in the 1940s. Calendrical decimalisation has been attempted, particularly notably during the French Revolution (amongst the same reforms which brought us the Metric System), as well as in the USSR. Switching to a ten-day week was exceedingly difficult given a) the traditions of seven-day cycles, particularly in religious contexts, as well as an external world based on the seven-day week.
In reference to the above tweet, it might surprise you to know that at times in the past (and per Wikipedia, even in some cultures today[0]) March has been considered the first Month, meaning that the new year would start on March 1, the leap day would be the last day of the year, and September, October, November and December would in fact be the seventh, eighth, ninth and tenth months of the year.
to be fair to us the aliens calendar is likely impenetrable as well, especially if they did agriculture. The more I learn about ancient societies the more I learn that calendars were really important and really complicated. It was the hobby of many rich people to stare at the sky and figure out how the stars move based on how the temprature feels and the daylight length. This let them calculate better when to plant/harvest crops, which grow based on the seasons. Calculating the exact number of days including fraction in a year is a nightmare before you figure out the mechanics of how orbits work, which is mindblowingly complicated to do just looking at the sky, and if you get it wrong your food production WILL slowly get worse. Many larger societies had whole quasi state/religous orders whose whole function was to keep the calendar working.
Compare for example the mayan calendar. Or the orthodox, or syrian, or basically any culture's calendar. None make sense.
I still think we should just have 12 months of 30 days and then a ~5 day long party at the end of the year. Or we could do 12 * 28 and then a 24 day bonus month.
The Mayan Haab` calendar was kind of the opposite of that, 18x20 with 5 "nameless days" at the end. The nameless days were considered a dangerous, unlucky, and very unparty time though.
It's highly likely that aliens have to deal with that as well. It's to combat the mismatched division of the planet doing a full rotation around the sun and the planet doing a full rotation itself. They might even have more oddities.
I once thought it would make more sense to have a calendar of 9 months of 8 weeks with 5 days per week (or 5wks * 8days) with a 5 day 'solstice period' at the end/beginning of every year (6 days every 4th year).
"The confirmed exoplanet with the shortest orbit is K2-137b, which orbits its host star, K2-137b once every 4 hours, 18 minutes. The planet is 0.89±0.09 times the mass of Earth, and orbits its host star at just 0.0058 times the distance of Earth from the sun."
Well, "Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin–orbit resonance, meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun."
The article mentions that its surface temperature is around 430 degrees Celsius.
It's that "low" because its star also radiates way less energy than our sun.
But still, "habitable zone" means liquid water, which you might not find there given the pressures/temperatures involved. Maybe sufficiently cold spots could exist in the areas facing away from its star.
So could you say it's in the habitable zone? Depends on your understanding of the term.
I think it's fair to say that we as a species have no idea what is a habitable zone. We're extrapolating from a set of 1, and even in looking for liquid water you're better off looking at moons far from our Sun than on Mars which is in our habitable zone.
A habitable zone is simply defined as the region which is most likely to be able to sustain the conditions for life in the form that we know of it.
Of course we don't know if other chemistries of life are possible, but that doesn't mean we can't define a habitable zone based on what we do know and expand it later if necessary.
As for looking at moons far from the star, it's barely a reliable means of confirming liquid water even within our own system, good luck detecting liquid water on an exomoon orbiting a far out exoplanet.
Mars is in our habitable zone and has plenty of evidence of having had liquid water flowing on its surface. The evidence of it having had conditions which could sustain some Earth-like life on it has only been increasing, making our current idea of habitable zones pretty promising. The fact that it currently doesn't have any liquid water on the surface has little bearing on that.
I mean yes, but also meh. They’re making the progress they need to but purely deducing from logic why will it be surprising that a good fraction of exoplanets have water when when a good fraction in our system do.
The main breakthrough is detecting anything at all on an exoplanet which can hopefully expand to more biologically relevant molecules in the future.
