A close look at one of TRAPPIST-1's planets shows it's bare and baking:
At this point, we've discovered lots of exoplanets that fall under the general label "Earth-like." They're rocky, and many orbit at distances from their host stars to potentially have moderate temperatures. But "like" is doing a lot of work there. In many cases, we have no idea whether they even have an atmosphere, and the greenhouse effect means that the atmosphere can have a huge impact on the planet's temperature. So the Earth-like category can include dry, baking hellscapes like Venus with its massive atmosphere, as well as dry, frozen tundras with sparse atmospheres like Mars.
But we're slowly getting the chance to image the atmospheres of rocky exoplanets. And today, researchers are releasing the results of turning the Webb Space Telescope on a rocky planet orbiting a nearby star, showing that the new hardware is so sensitive that it can detect the star blocking out light originating from the planet. The results suggest that the planet has very little atmosphere and is mostly radiating away heat from being baked by its nearby star.
TRAPPIST-1 is a small, reddish star—in astronomical terminology, it's an "ultra-cool dwarf"—that's about 40 light-years from Earth. While the star itself is pretty nondescript, it's notable for having lots of planets, with seven in total having been identified so far. All of these are small, rocky bodies, much like the ones that occupy the inner portion of our Solar System. While the star emits very little light, the planets are all packed in closer to it than Mercury is to the Sun.
[...] So, TRAPPIST-1 provides a fantastic opportunity—really, seven opportunities—to test some of our ideas about exoplanet atmospheres. And both the Hubble and Spitzer space telescopes have imaged some starlight that passes close to some of the planets as they pass between Earth and TRAPPIST-1. These observations didn't provide any indications of an atmosphere, setting limits on how thick any gases above these planets could be.
[...] The Webb is so sensitive that it enabled an entirely different sort of observation. Most attempts at imaging exoplanet atmospheres rely on light from the host star that grazes the planets, and thus would pass through any atmosphere that's there. This relies on the planet passing in front of the host star.
This new work relies on the planet passing behind the host star—having the star eclipse the planet, in other words. Shortly before and after that happens, the telescope will receive light from both the star itself and any light that's emitted or reflected by the planet. This sort of "secondary eclipse" is difficult to detect, given that the star is so much brighter. In addition, the Webb's detectors are sensitive to wavelengths that would allow it to detect any carbon dioxide.
This initial work focused on the innermost planet, TRAPPIST-1b, where the star would be roughly 1,000 times brighter than any light we should see from the planet. [...]
The work used the drop in light caused by the secondary eclipse to infer what portion of the light outside the eclipse was coming from the planet. This light would be a mix of reflected light and heat given off the planet, which is baked by roughly four times the radiation that Earth receives from the Sun. But, by imaging in the infrared, most of what's being detected is primarily the heat radiated off the planet. By assuming this is approximately a black body radiation, it's possible to estimate the temperature of the planet needed to produce that radiation.
This produced a result of about 500 K, or 230° C, which tells us there's probably no atmosphere.
(Score: 2, Funny) by Runaway1956 on Wednesday March 29, @10:58PM (7 children)
To be earthlike, there must be some assholes living on the planet.
Abortion is the number one killed of children in the United States.
(Score: 2) by Tork on Wednesday March 29, @11:32PM (6 children)
Slashdolt Logic: "25 year old jokes about sharks and lasers are +5, Funny." 💩
(Score: 2) by mcgrew on Wednesday March 29, @11:50PM (3 children)
Why do you think alien organisms would be anything at all like us? That's the biggest hurdle to pretense of reality in any SF movie, the humanoid space aliens. An octopus is likely to look more like us than a Vogon would.
Carbon, The only element in the known universe to ever gain sentience
(Score: 4, Interesting) by Tork on Thursday March 30, @12:23AM (1 child)
If I zipped ahead to the future and our extra-terrestrial buddies all looked like Star Trek's bumpy headed aliens, I actually would not be that surprised. I don't expect it, but if they turned around and said something like: "Yah, hoo-maaahn-oids that have more than two arms always go extinct via devastating nuclear wars..." ... well I might be able to wrap my head around that.
I don't have any real solid beliefs here, I mainly think whatever we guess it is we'll be wrong for circumstances we haven't considered. I do love thinking about it, though. Like.. are we alone in the universe? Many people will say the odds are astronomically for it, but I'm in the camp that says it's 50-50. Either we are or we aren't. Now that flies in the face of the zillions of possibilities our massive universe has for us, and yes I do respect that. But it does occur to me that if we're in a universe so massive that every possibility is played out, one of those possibilities is that rare events happen. If that's right, then there's even a possibility that Earth is the rarest planet in the whole universe and we're the only beings that recognize that! Heh.
If you're wondering where I'm coming from on this, I like to dabble in creative writing. The whole concept of alien life is academic to me and I treat it as such. What I mean is I'm not being contrarian, just having fun exploring it... at least until the mother ship arrives and settles it for us. ;)
Slashdolt Logic: "25 year old jokes about sharks and lasers are +5, Funny." 💩
(Score: 2) by mcgrew on Saturday April 01, @09:47PM
As-in I have most of the same bones as my cat.
You and your cat are closely related, mammals were brand new 65 million years ago when the dinosaurs died. How about the octopus, eight arms, nine brains, and no bones? And they're from the same evolution as you and your cat.
I've noticed few if any humanoid aliens in written SF. I suspect that the aliens are humanoid in movies because until recently, puppets looked lame and were hard to do.
In my book Nobots, the area 51 grays are our descendants from ten million years in the future, and they killed Lincoln and Kennedy. I agree wholeheartedly with you.
Carbon, The only element in the known universe to ever gain sentience
(Score: 0) by Anonymous Coward on Thursday March 30, @08:18AM
It's possible that convergent evolution would ensure that dominant alien species in the universe tend to develop bipedal humanoid forms.
Brainless microbes aren't going to build a spaceship. Sea creatures like octopuses won't be covering their planet with electric lighting, especially if it's an ocean world. A four-legged horse-like land dweller won't be wielding weapons, unless it evolves some arms.
(Score: 1) by Runaway1956 on Wednesday March 29, @11:56PM (1 child)
But - if they don't shit like us, then it can't be 'earthlike', can it? We - meaning mammals, reptiles, amphibians, avians, and whatever outliers I'm missing - have quite literally shit on every square inch of the surface of earth, millions of times over. A planet NOT covered in shit cannot be considered to be 'earthlike'. :^)
Abortion is the number one killed of children in the United States.
(Score: 4, Funny) by Tork on Thursday March 30, @02:13AM
Slashdolt Logic: "25 year old jokes about sharks and lasers are +5, Funny." 💩
(Score: 2) by mcgrew on Wednesday March 29, @11:41PM (2 children)
How can they image a planet ten times farther from Earth than Proxima Centauri B [wikipedia.org] but not that planet?
I'm glad this is posted, in the novel it's about as big as Mars. I screwed up. Not sure where that came from but I need to fix it. It looks like I'll be typing a lot of words tonight. It also creates some very large problems for a lot of the crew, who grew up and lived on Mars and asteroids and can't take gravity that strong.
Carbon, The only element in the known universe to ever gain sentience
(Score: 1, Insightful) by Anonymous Coward on Thursday March 30, @12:23AM
> image
This is the cause of your confusion. There are no images, as conventionally defined.
(Score: 1, Insightful) by Anonymous Coward on Thursday March 30, @08:21AM
JWST is using spectroscopy to examine exoplanet atmospheres. It might "image" some exoplanets, but they are likely hot Jupiters and look like blobs:
https://blogs.nasa.gov/webb/2022/09/01/nasas-webb-takes-its-first-ever-direct-image-of-distant-world/ [nasa.gov]