Starship Asterisk*

by **johnnydeep** » Tue Jul 09, 2024 6:47 pm

Chris Peterson wrote: ↑Tue Jul 09, 2024 6:36 pm
johnnydeep wrote: ↑Tue Jul 09, 2024 6:26 pm
Chris Peterson wrote: ↑Tue Jul 09, 2024 6:23 pm
Life formed very quickly on Earth, when the planet would not support much of anything that exists here today. If Earth is any example, life is fast and easy. It's the jump from simple life (like algae and prokaryotic cells) to complex life (animals) that took a long time, and may well demand long-term stability.
Ok. So does this mean you are also skeptical that super Earths would be more likely for foster intelligent life than smaller planets?
I don't think I have enough information to form much of an opinion. I do take the example of Earth to strongly suggest that you need long term environmental stability to avoid huge mass extinctions that might prevent life complex enough to become highly intelligent (I'll take that as "technological"). Your questions about super Earth's are therefore quite reasonable ones to ask.

by **Chris Peterson** » Tue Jul 09, 2024 6:36 pm

johnnydeep wrote: ↑Tue Jul 09, 2024 6:26 pm
Chris Peterson wrote: ↑Tue Jul 09, 2024 6:23 pm
johnnydeep wrote: ↑Tue Jul 09, 2024 6:16 pm

This article says that "super Earths" might actually be better at fostering life than our puny little Earth, due to more plate tectonic activity and the greater ability to hold on to an atmosphere, both due to the higher gravity and internal heat. (But I'm not quite convinced: a thicker atmosphere might also cause a run-away greenhouse effect, and more plate tectonics might not allow enough time for life to evolve in the first place.)

Life formed very quickly on Earth, when the planet would not support much of anything that exists here today. If Earth is any example, life is fast and easy. It's the jump from simple life (like algae and prokaryotic cells) to complex life (animals) that took a long time, and may well demand long-term stability.
Ok. So does this mean you are also skeptical that super Earths would be more likely for foster intelligent life than smaller planets?

I don't think I have enough information to form much of an opinion. I do take the example of Earth to strongly suggest that you need long term environmental stability to avoid huge mass extinctions that might prevent life complex enough to become highly intelligent (I'll take that as "technological"). Your questions about super Earth's are therefore quite reasonable ones to ask.

by **johnnydeep** » Tue Jul 09, 2024 6:26 pm

Chris Peterson wrote: ↑Tue Jul 09, 2024 6:23 pm
johnnydeep wrote: ↑Tue Jul 09, 2024 6:16 pm

This article says that "super Earths" might actually be better at fostering life than our puny little Earth, due to more plate tectonic activity and the greater ability to hold on to an atmosphere, both due to the higher gravity and internal heat. (But I'm not quite convinced: a thicker atmosphere might also cause a run-away greenhouse effect, and more plate tectonics might not allow enough time for life to evolve in the first place.)

Life formed very quickly on Earth, when the planet would not support much of anything that exists here today. If Earth is any example, life is fast and easy. It's the jump from simple life (like algae and prokaryotic cells) to complex life (animals) that took a long time, and may well demand long-term stability.

Ok. So does this mean you are also skeptical that super Earths would be more likely for foster intelligent life than smaller planets?

by **Chris Peterson** » Tue Jul 09, 2024 6:23 pm

johnnydeep wrote: ↑Tue Jul 09, 2024 6:16 pm

This article says that "super Earths" might actually be better at fostering life than our puny little Earth, due to more plate tectonic activity and the greater ability to hold on to an atmosphere, both due to the higher gravity and internal heat. (But I'm not quite convinced: a thicker atmosphere might also cause a run-away greenhouse effect, and more plate tectonics might not allow enough time for life to evolve in the first place.)

Life formed very quickly on Earth, when the planet would not support much of anything that exists here today. If Earth is any example, life is fast and easy. It's the jump from simple life (like algae and prokaryotic cells) to complex life (animals) that took a long time, and may well demand long-term stability.

by **johnnydeep** » Tue Jul 09, 2024 6:16 pm

Ann wrote: ↑Tue Jul 09, 2024 5:45 am I was so crushed yesterday after I lost a long post that I had spent hours composing, so that after I had mostly restored that post, I couldn't bring myself to make another. But I really wanted say that the most common type of exoplanets (of those that we have so far detected) are neither "Jupiters" nor "Neptunes", but super-Earths and mini-Neptunes!

BBC Sky at Night Magazine wrote:

Super-Earths and mini-Neptunes are the most common planets. So why does our Solar System have none?

"It’s interesting, because in our Solar System we have this big gap," says Eliza Kempton, who researches exoplanets at the University of Maryland.

"We have the small rocky planets, we have the big gas giant planets, and we don’t have anything in between – we have this big gap between Neptune and Earth."

Most of the new exoplanets found so far are in between Earth and Neptune in size, so-called super-Earths and mini-Neptunes. Credit: NASA/ESA/CSA and STScI

The solar system has no planets between the Earth and Neptune in size, but the Universe - at least the local universe - seems to love to make these in-betweeners!

I have to wonder why our own solar systems lacks what appears to be the most common types of planets in the local universe.

And what would the solar system have been like it the Earth had been a super-Earth? Would it still have been habitable? Would we have been here? No, we, as Homo sapiens, wouldn't have been here, because our bones wouldn't have been able to withstand the gravity (or so I think, anyway). Could other intelligent beings have roamed this super-Earth?

Ann

This article says that "super Earths" might actually be better at fostering life than our puny little Earth, due to more plate tectonic activity and the greater ability to hold on to an atmosphere, both due to the higher gravity and internal heat. (But I'm not quite convinced: a thicker atmosphere might also cause a run-away greenhouse effect, and more plate tectonics might not allow enough time for life to evolve in the first place.)

Plus, super Earths might even explain the Fermi Paradox by positing that if most intelligent life developed on super Earths, "they" would be less likely to consider Earth as a possible target to look for life on!

https://www.space.com/7613-super-earths ... -life.html

(PS - not sure why this article is poorly rendered in my browser with lots of "?" marks, fut it's still readable.)

by **Chris Peterson** » Tue Jul 09, 2024 1:27 pm

Christian G. wrote: ↑Tue Jul 09, 2024 12:52 pm
Ann wrote: ↑Tue Jul 09, 2024 5:45 am I was so crushed yesterday after I lost a long post that I had spent hours composing, so that after I had mostly restored that post, I couldn't bring myself to make another. But I really wanted say that the most common type of exoplanets (of those that we have so far detected) are neither "Jupiters" nor "Neptunes", but super-Earths and mini-Neptunes!

BBC Sky at Night Magazine wrote:

Super-Earths and mini-Neptunes are the most common planets. So why does our Solar System have none?

"It’s interesting, because in our Solar System we have this big gap," says Eliza Kempton, who researches exoplanets at the University of Maryland.

"We have the small rocky planets, we have the big gas giant planets, and we don’t have anything in between – we have this big gap between Neptune and Earth."

Most of the new exoplanets found so far are in between Earth and Neptune in size, so-called super-Earths and mini-Neptunes. Credit: NASA/ESA/CSA and STScI

The solar system has no planets between the Earth and Neptune in size, but the Universe - at least the local universe - seems to love to make these in-betweeners!

I have to wonder why our own solar systems lacks what appears to be the most common types of planets in the local universe.

And what would the solar system have been like it the Earth had been a super-Earth? Would it still have been habitable? Would we have been here? No, we, as Homo sapiens, wouldn't have been here, because our bones wouldn't have been able to withstand the gravity (or so I think, anyway). Could other intelligent beings have roamed this super-Earth?

Ann
Could it be because in our planetary system Jupiter was the first planet to form and influenced, to some degree, how the other planets would form, how many could form, how much "rock" would be available for rocky planets vs confined to the asteroid belt by its gravitational influence? I'm tempted to blame it on Jupiter. Dinosaurs certainly would!

No, the evidence says all the planets formed at the same time. Their composition depended on their distance from the Sun. Jupiter, however, played a large role in ejecting many planets that are no longer here and in re-arranging the positions of those that are.

by **Christian G.** » Tue Jul 09, 2024 12:52 pm

Ann wrote: ↑Tue Jul 09, 2024 5:45 am I was so crushed yesterday after I lost a long post that I had spent hours composing, so that after I had mostly restored that post, I couldn't bring myself to make another. But I really wanted say that the most common type of exoplanets (of those that we have so far detected) are neither "Jupiters" nor "Neptunes", but super-Earths and mini-Neptunes!

BBC Sky at Night Magazine wrote:

Super-Earths and mini-Neptunes are the most common planets. So why does our Solar System have none?

"It’s interesting, because in our Solar System we have this big gap," says Eliza Kempton, who researches exoplanets at the University of Maryland.

"We have the small rocky planets, we have the big gas giant planets, and we don’t have anything in between – we have this big gap between Neptune and Earth."

Most of the new exoplanets found so far are in between Earth and Neptune in size, so-called super-Earths and mini-Neptunes. Credit: NASA/ESA/CSA and STScI

The solar system has no planets between the Earth and Neptune in size, but the Universe - at least the local universe - seems to love to make these in-betweeners!

I have to wonder why our own solar systems lacks what appears to be the most common types of planets in the local universe.

And what would the solar system have been like it the Earth had been a super-Earth? Would it still have been habitable? Would we have been here? No, we, as Homo sapiens, wouldn't have been here, because our bones wouldn't have been able to withstand the gravity (or so I think, anyway). Could other intelligent beings have roamed this super-Earth?

Ann

Could it be because in our planetary system Jupiter was the first planet to form and influenced, to some degree, how the other planets would form, how many could form, how much "rock" would be available for rocky planets vs confined to the asteroid belt by its gravitational influence? I'm tempted to blame it on Jupiter. Dinosaurs certainly would!

by **Ann** » Tue Jul 09, 2024 5:45 am

I was so crushed yesterday after I lost a long post that I had spent hours composing, so that after I had mostly restored that post, I couldn't bring myself to make another. But I really wanted say that the most common type of exoplanets (of those that we have so far detected) are neither "Jupiters" nor "Neptunes", but super-Earths and mini-Neptunes!

BBC Sky at Night Magazine wrote:

Super-Earths and mini-Neptunes are the most common planets. So why does our Solar System have none?

"It’s interesting, because in our Solar System we have this big gap," says Eliza Kempton, who researches exoplanets at the University of Maryland.

"We have the small rocky planets, we have the big gas giant planets, and we don’t have anything in between – we have this big gap between Neptune and Earth."

: Most of the new exoplanets found so far are in between Earth and Neptune in size, so-called super-Earths and mini-Neptunes. Credit: NASA/ESA/CSA and STScI

The solar system has no planets between the Earth and Neptune in size, but the Universe - at least the local universe - seems to love to make these in-betweeners!

I have to wonder why our own solar systems lacks what appears to be the most common types of planets in the local universe.

And what would the solar system have been like it the Earth had been a super-Earth? Would it still have been habitable? Would we have been here? No, we, as Homo sapiens, wouldn't have been here, because our bones wouldn't have been able to withstand the gravity (or so I think, anyway). Could other intelligent beings have roamed this super-Earth?

Ann

by **Ann** » Tue Jul 09, 2024 4:35 am

Avalon wrote: ↑Tue Jul 09, 2024 3:47 am All of the illustrated exoplanets appear so stripe-y, like our Jupiter. Is that because they are nearly all thought to be gas giants? Is there any way to tell if they are gas giants or rocky planets and why are they virtually all shown to have stripes?

If astronomers can measure a planet's size and mass, they can also figure out if the planet is rocky or if it is a gas giant. A planet with a comparatively high mass for its size is rocky. A planet with a comparatively low mass for its size is a gas giant.

: The density of Saturn is so low that it would float in water. Credit: r/megalophobia

There is admittedly a third possibility. A planet might be a "water world", almost completely made of ices.

As for whether most exo-gas giants are obviously stripey, my guess is that stripes are typically not "dominant". In the solar system, only Jupiter is obviously stripey, in the same way that only Saturn has bright and "obvious" rings. But Jupiter, Uranus and Neptune have rings too, but they are very hard to spot. And Saturn is stripey, but its stripes or bands are mostly hidden under a layer of haze.

: Saturn has stripes (or bands), but they are hard to spot. Credit: NASA/JPL/SPACE SCIENCE INSTITUTE

To my knowledge, Uranus doesn't have stripes, but Neptune may have them. The JWST portrait of Neptune suggests it does. (Naturally JWST reveals the rings of Neptune, too.)

: Neptune in infrared. Credit: JWST.

Stripes could signify fast rotation. Stripey Jupiter is the fastest-rotating body in the solar system.

: Fast-rotating Jupiter is obviously stripey. The picture is taken from a Youtube video.

I would guess that most gas giants are made to look stripey in the APOD because the planets look more interesting that way!

After all, consider Uranus. How boring is featureless Uranus? All right. Infrared images make Uranus look quite stunning! Now we can see the rings of Uranus, too. And perhaps a hint of stripes?

: Pole-on Uranus in infrared light by JWST. Are we perhaps seeing a hint of stripes here?

: Uranus. Credit: NASA/JPL-Caltech

Ann

by **Ann** » Tue Jul 09, 2024 4:25 am

shaileshs wrote: ↑Mon Jul 08, 2024 3:41 pm Apart from tons of size and color variations, 3 things i find interesting -
1) very few have rings
2) spinning axis seems so randomly distributed (any direction in 360 degrees)
3) bottom right elliptical/egg shaped planet (the ONLY one of such odd shape)

We really don't know how many exoplanets have rings. In the solar system, both gas giants and both ice giants have rings, but only Saturn's rings are so substantial that they are bright and obvious. To my knowledge, no exoplanet so far has been definitely proved to have rings, although it seems certain that some - or many - of them do. But we have no idea what fraction of exoplanets have Saturn-like rings.

Ann

by **zendae** » Tue Jul 09, 2024 4:01 am

Whitman's could make a chocolate box out of it.

by **Avalon** » Tue Jul 09, 2024 3:47 am

All of the illustrated exoplanets appear so stripe-y, like our Jupiter. Is that because they are nearly all thought to be gas giants? Is there any way to tell if they are gas giants or rocky planets and why are they virtually all shown to have stripes?

by **johnnydeep** » Mon Jul 08, 2024 9:19 pm

Guest wrote: ↑Mon Jul 08, 2024 8:55 pm
Iksarfighter wrote: ↑Mon Jul 08, 2024 6:50 am Image is too small, impossible to read the names.
Even when you click on the image and zoom in on it the titles are very blurry.
I'm sure if I was more experienced I could make better guesses.

You missed bystander's post above, which ultimately gets you to this VERY high-res image: https://www.halcyonmaps.com/the-exoplanet-zoo/ if you click through:

https://images-wixmp-ed30a86b8c4ca88777 ... -TGcP2Ym1A

7100 × 4686
8.69 MB

by **Guest** » Mon Jul 08, 2024 8:55 pm

Iksarfighter wrote: ↑Mon Jul 08, 2024 6:50 am Image is too small, impossible to read the names.

Even when you click on the image and zoom in on it the titles are very blurry.
I'm sure if I was more experienced I could make better guesses.

by **johnnydeep** » Mon Jul 08, 2024 5:31 pm

The creator of this image sure does have a bunch of very nice images of other stuff at his site! Great stuff!

As for exoplanets, the vast majority of exoplanets that we can currently detect fairly well have orbital planes around their host stars that are near perpendicular to our line of sight, correct? That is, both the transiting and wobble methods of detection rely on the planet either passing in front of, or close to in front of, their stars, respectively. But there are several other detection methods that could be used to detect planets in other orbits, via "direct imaging" for example. Can we detect star wobbles perpendicular to our line of sight?

And then there are the rogue planets that we can detect when they transit background stars.

PS - gripe: I can scarcely bear to listen to any podcast from the new (as of two years ago) host of "Planetary Radio" that's about exoplanets because she insists on pronouncing it "eggsoplanet"! So maddening.

by **shaileshs** » Mon Jul 08, 2024 3:41 pm

Apart from tons of size and color variations, 3 things i find interesting -
1) very few have rings
2) spinning axis seems so randomly distributed (any direction in 360 degrees)
3) bottom right elliptical/egg shaped planet (the ONLY one of such odd shape)

by **Roy** » Mon Jul 08, 2024 3:10 pm

How do they infer the size of the planets? And that some are ringed?

by **Iksarfighter** » Mon Jul 08, 2024 2:44 pm

OK TY !

by **bystander** » Mon Jul 08, 2024 2:28 pm

Iksarfighter wrote: ↑Mon Jul 08, 2024 6:50 am Image is too small, impossible to read the names.

APOD Robot wrote: ↑Mon Jul 08, 2024 4:05 am Explanation: ... Featured here ...

by **Chris Peterson** » Mon Jul 08, 2024 1:21 pm

Ann wrote: ↑Mon Jul 08, 2024 1:14 pm
As you can see, WASP-12b is egg-shaped due to its proximity to its parent star. Yes, but both the APOD and illustrator Robert Lea (who illustrated the SPACE article about WASP-12b) got the planet's color wrong!

Artist's depiction of WASP-12b's atmosphere being tidally stripped by its parent star. Credit: ESA/Hubble
Because WASP-12b is black! Yes, it really is!

Wikipedia wrote about WASP-12b:

In September 2017, researchers working on the HST announced that WASP-12b reflects just 6% of the light that shines on its surface. As a result, the exoplanet has been described as "black as asphalt" and as "pitch black."

Well, that describes the Moon, as well, but visually, we don't describe it or see it as black. These things only become relevant when we place objects with different brightnesses next to each other for comparison. A body that reflects 6% of its star's light will be dazzling to our eyes if that star isn't in front of us at the same time.

by **Ann** » Mon Jul 08, 2024 1:14 pm

I just wrote a long post about this APOD and it disappeared!

: Exoplanet Zoo: Other Stars. Illustration Credit & Copyright: Martin Vargic, Halcyon Maps

Okay, I've stopped crying now, and I like today's APOD! It looks like a box of chocolates, I mean, it looks like a, I guess, a box of planets!

Click to play embedded YouTube video.

As Forrest Gump said, you never know what you're going to get when you pick a piece of chocolate out of a box. And you never know what you'll get when you find a new planet orbiting a distant star. But we humans got one of those rare planet gems of the Universe, a planet that is not just habitable but also richly inhabited,

: A beautiful Earth. Credit: Ray Caesar.

Right, that picture may be a bit over the top! But seriously, how far away is the next planet that hosts the equivalence of trees, flowers, birds and people?

Let's get back to the APOD. I'm critical about the fact that the APOD uses color instead of size to show the difference between Neptune-type and Jupiter-type exoplanets. Surely it is size and mass that sets Jupiter-type exoplanets apart from Neptune-type ones?

I'm also critical about the fact that Neptune-type planets are shown as blue and Jupiter-type planets are shown as red or tan. Actually we have no idea what color most exoplanets are! But in a very few cases we do know about their colors, and those hues are slightly shocking:

: Blue hot Jupiter HD 189733b

NASA Science wrote:

This illustration shows HD 189733b, a huge gas giant that orbits very close to its host star HD 189733. The planet's atmosphere is scorching with a temperature of over 1000 degrees Celsius, and it rains glass, sideways, in howling 7000 kilometre-per-hour winds. At a distance of 63 light-years from us, this turbulent alien world is one of the nearest exoplanets to Earth that can be seen crossing the face of its star. By observing this planet before, during, and after it disappeared behind its host star during orbit, astronomers were able to deduce that HD 189733b is a deep, azure blue — reminiscent of Earth's colour as seen from space.

Another "shocking" planet color is seen in WASP-12b. This planet is featured prominently in the lower right corner of the APOD:

As you can see, WASP-12b is egg-shaped due to its proximity to its parent star. Yes, but both the APOD and illustrator Robert Lea (who illustrated the SPACE article about WASP-12b) got the planet's color wrong!

: Artist's depiction of WASP-12b's atmosphere being tidally stripped by its parent star. Credit: ESA/Hubble

Because WASP-12b is black! Yes, it really is!

Wikipedia wrote about WASP-12b:

In September 2017, researchers working on the HST announced that WASP-12b reflects just 6% of the light that shines on its surface. As a result, the exoplanet has been described as "black as asphalt" and as "pitch black."

So indeed, Horatio, there are more things in Heaven and Earth and the rest of the Universe than are dreamt of in your philosophy! 🖐

Ann

by **Iksarfighter** » Mon Jul 08, 2024 6:50 am

Image is too small, impossible to read the names.

by **APOD Robot** » Mon Jul 08, 2024 4:05 am

Exoplanet Zoo: Other Stars

Explanation: Do other stars have planets like our Sun? Surely they do, and evidence includes slight star wobbles created by the gravity of orbiting exoplanets and slight star dimmings caused by orbiting planets moving in front. In all, there have now been over 5,500 exoplanets discovered, including thousands by NASA's space-based Kepler and TESS missions, and over 100 by ESO's ground-based HARPS instrument. Featured here is an illustrated guess as to what some of these exoplanets might look like. Neptune-type planets occupy the middle and are colored blue because of blue-scattering atmospheric methane they might contain. On the sides of the illustration, Jupiter-type planets are shown, colored tan and red from the scatterings of atmospheric gases that likely include small amounts of carbon. Interspersed are many Earth-type rocky planets of many colors. As more exoplanets are discovered and investigated, humanity is developing a better understanding of how common Earth-like planets are, and how common life might be in the universe.

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