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It has been thought that the existence of plate tectonics has been a significant factor in the shaping of our planet and the evolution of life. Mars and Venus don’t experience such movements of crustal plates but then the differences between the worlds is evident. The exploration of exoplanets too finds many varied environments. Many of these new alien worlds seem to have significant internal heating and so lack plate movements too. Instead a new study reveals that these ‘Ignan Earths’ are more likely to have heat pipes that channel magma to she surface. The likely result is a surface temperature similar to Earth in its hottest period when liquid water started forming. 

Plate tectonics explains the movement and interaction of the Earth’s upper layers. More accurately, the lithosphere which is composed of the crust and upper layer of the mantle. It is divided into a number of pieces known as tectonic plates which float around on the semi-fluid layer below called the asthenosphere. Where the plates meet, various geological features form such as mountains, volcanoes and trenches. 

Location of the Mariana Trench. Credit: Wikipedia Commons/Kmusser

The process has been a crucial factor in the evolution of life on our planet. The shifting of landmasses has created new habitats and caused populations to become isolated allowing for individual ecosystems to form. Collisions of plates led to mountain range development which influenced the weather patterns and climate. Volcanic activity driven by plate movement led to soils becoming fertile, plant life to flourish and the release of gasses like carbon dioxide into the atmosphere that helped the planet regulate its climate. It really has been a crucial process in the evolution of our planet. 

A typical “black smoker” volcanic vent here on E

In some respects the process also stops a planet’s internal environment from overheating. There is a train of thought that if Earth didn’t have such plate movement then it may be too hot internally for a stable environment to evolve. This was the subject of the paper by Matthew Reinhold and Laura Schaefer that was published in Advancing Earth and Space Sciences. 

They explored the liklihood that such a world might have so much internal heating that instead, it would resemble bodies like Jupiter’s moon Io. Here we see intense levels of volcanism where laval violently erupts hundreds of kilometres into the atmosphere which is full of toxic gasses. It’s not just a lack of plate tectonics that can lead to high levels of internal heating. Tidal effects can cause worlds to have one face constantly pointing to the Sun giving a wide range of surface temperatures.

These are JunoCam images of Jupiter’s moon Io from its 3 February 2024 encounter. The first two images show Io illuminated by Jupiter-shine, and the rest are lit up by sunlight. The new volcano was captured in the second image in the sequence. Credit: NASA/JPL-Caltech/SwRI/MSSS.

Collectively these worlds are known casually as Ignan Earth’s and they are the target of the paper, to explore whether they are habitable. Exploring the geology of the bodies in our Solar System gives great insight. The team demonstrate that it is likely that worlds with high internal temperatures will develp a solid mantle. The crust will remain largely stable as a result with the only likely activity, heat-pipe tectonics – where some of the internal heat is transferred to the surface for example from volcanic activity. 

The team were able to model the the likely surface temperature range based upon a number of different types of world and found that, contrary to previous expectations, a wide range of internal heating rates may well lead to worlds where the environment is conducive to habitability.

Source : Ignan Earths: Habitability of Terrestrial Planets With Extreme Internal Heating

The post Planets Without Plate Tectonics Could Still Be Habitable appeared first on Universe Today.

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Well, I’m not sure that most American comedians working now are Jews, but surely they are still way overrepresented compared to the proportion of Jews in America, which is only 2.4%.

In fact, the first two comedians I thought of still working were Jerry Seinfeld and Sarah Silverman, both of course of the Hebrew persuasion.  But think of the great comedians of the past 50 years, and then of their religion.  As one site reports, “In 1978, 80 percent of American standup comedians were Jewish.”  But it’s not just the standups!

Here are are just a few well-known Jewish comedians (I’m leaving out ones that few people know, like Fanny Brice).

Groucho Marx
Mel Brooks
Rodney Dangerfield
Mort Sahl
Don Rickles
Henny Youngman
Jerry Seinfeld
George Burns
Lenny Bruce
Joan Rivers
Jackie Mason
Gilda Radner
Milton Berle
Curly, Moe, and Shemp Howard of The Three Stooges
Carl Reiner
Bill Maher
Jerry Lewis

I won’t go on; there are too many!  In fact, Wikipedia has three full pages of Jewish comedians, listed alphabetically (start here and continue by clicking at the bottom of each page).

There must be reasons for this inequity in comedy, and I’m also sure that many people have discussed this. But I don’t know of the speculations, so I asked three Jewish friends (one of them is ME) to give their theories.

1.) Malgorzata, my surrogate Polish mother:

Malgorzata lightheartedly suggested that the tendency of Jews to offer humor is the result of natural selection: since Jews have experienced dark times and pogroms throughout much of their history, those Jews who could laugh at themselves and the world were less likely to be depressed and to kill themselves, or more likely to tolerate intolerable situations. If there is genetic variation for humor, those with more “humor” genes would survive and reproduce. Other groups haven’t had such a history, ergo Jews tend to be comedians. (I am paraphrasing what she told me.) natural selection for people who could laugh and have a sense of humor because they would commit suicide.

2.) Me (PCC[E]):

I have a variant based on the impression of many Jews that the whole world of non-Jews hates them, something that is not far from the truth.  Jews, then, suffer from a lack of love from others.  To compensate for this, they become comedians, for what better way is there to get love and approbation than to have an audience laugh at your jokes? And they are not laughing at you, but laughing with you. That is s a form of love. This is a cultural explanation for the surfeit of Jewish comedians.

3.) Steve Pinker.  I asked him for his explanation, and this is his response (quoted with permission). Part of his theory jibes with Malgorzata’s, but he is looking for an explanation that itself is funny:

This has been a puzzle that others have (humorlessly) considered, including Ruth Wisse (former Harvard colleague and fellow Montrealer, grew up with my mother), and Howard Jacobson (British novelist, unlike most Brits proud of being Jewish). Something about humor being a subversive tactic, or a coping mechanism of the powerless and oppressed. The analyses were neither convincing nor funny.

But they may be consistent with the fact that many African Americans have been great comedians – Moms Mabley, Pigmeat Markham, Nipsey Russell, Flip Wilson, Richard Pryor, Eddie Murphy, Chris Rock, Dave Chappelle, and the greatest of all, Bill Cosby. (“Noah!”)

Of course this is a lighthearted post, but there is a real phenomenon to be explained, and I invite readers to offer their own theory, which is theirs.

When was the last time you looked up into the night sky and saw the Milky Way? If you happen to live in one of the truly remote areas of the world, your answer might be “last night.” If you live in one of the generally “rural” areas of your country, you might remember how you used to see the Milky Way regularly, but the rise of LEDs, particularly the blue/white ones, has gradually erased the Milky Way from your nights. For the large majority of humans on our small world, the answer is “never.”

Light pollution has gradually stolen the night from us. Once powerful observatories such as Griffith Observatory have been blinded by our nocturnal illuminations, and modern telescopes must be built in the most remote areas of the world where light pollution is still manageable. Although we don’t notice it in the same way, the same is true for radio telescopes. Our days are filled with radio light, from mobile phones and Wi-Fi to the tire pressure sensors of a modern call. They all shine as bright in radio as an LED flashlight in the visible. But in recent years, both optical and radio telescopes have seen growing light pollution from another source: constellation satellites.

Companies such as Starlink have launched so many satellites that even in the most remote areas of the world, you can regularly see them near the horizon, particularly during dusk and dawn. For optical telescopes, the trails they create can be mitigated to a degree by making them less reflective. For radio telescopes, however, they pose a more serious and complex challenge.

Since Starlink and other constellations are communication satellites, they actively beam radio signals to Earth. Imagine if satellites had powerful floodlights shining over your house all the time, and you get the problem for radio observatories. One way to limit radio light pollution is to create forbidden zones where satellites don’t operate. For example, Starlink satellites go quiet over key regions of the National Radio Quiet Zone, as well as other large observatories across the world. But while this reduces the amount of light pollution, it doesn’t eliminate it.

An image of the NGC 5353/4 galaxy group made with a telescope at Lowell Observatory in Arizona, USA on the night of Saturday 25 May 2019. The diagonal lines running across the image are satellite trails of reflected light from more than 25 Starlink satellites as they passed through the telescope’s field of view. Credit: Victoria Girgis/Lowell Observatory

As a recent study points out, radio signals from Starlink satellites aren’t narrowly focused. Even when they go quiet over an observatory, they are active in areas near the observatories, and stray radio light can contaminate observations. As satellite constellations become more common, this stray radio light will gradually wash out the radio sky, in much the same way that LED lights from neighboring towns diminish your view of the Milky Way.

The situation has gotten serious enough that the IAU Centre for the Protection of the Dark, Quiet Sky from Satellite Constellation Interference (CPS) has called for specific steps to be taken to save the night sky. They urge the international community to implement regulations so that ground-based astronomy can remain viable in the future.

It’s clear that satellite constellations such as Starlink are a benefit to many people in the world. For some regions, it is the only way to have a connection to the internet. In the same way, inexpensive night lighting has allowed us to have safer, more comfortable lives. But it is worth being mindful of what we can lose. Our view of the heavens has deep roots in human culture, and it is worth preserving. Balancing our history with our future is something we can all strive to do better.

Reference: Dark, I. A. U., et al. “Call to Protect the Dark and Quiet Sky from Harmful Interference by Satellite Constellations.” arXiv preprint arXiv:2412.08244 (2024).

The post Astronomers are Losing the Night Sky (and Radio Sky) to Satellite Megaconstellations appeared first on Universe Today.

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Today’s Jesus and Mo strip, called “cheers,” isn’t particularly religious, but surely expresses the feelings of many people. (I for one will make no resolutions!) I don’t think the “booze is always bad for you” issue is yet settled, anyway.

Ecologist Susan Harrison of UC Davis has return with a fresh batch of photos. Susan’s captions and IDs are indented, and you can enlarge her photos by clicking on them.

Miscellaneous birds of late 2024

The only theme of this post is “birds I saw in late 2024 and haven’t used in a WEIT post yet.”  The first ones are from Shoreline Park in Mountain View, California.  Less than a mile from the Googleplex, 5 miles from Stanford University and 10 miles from Apple’s campus, this park lies on a stretch of southern San Francisco Bay that hosts many thousands of overwintering waterfowl and shorebirds.   Every year I get to enjoy its sights the day after Thanksgiving, when my siblings and their families gather for a meal and a birdwatching stroll.

American White Pelicans, Pelecanus erythrorhynchos, foraging along the shore in their majestically unhurried style:

Greater Yellowlegs, Tringa melanoleuca, staring into a very small abyss:

Snowy Egret, Egretta thula, looking like a movie star annoyed by paparazzi:

American Coot, Fulica americana, flaunting oversized webbed feet:

The next ones are from the vicinity of Davis, California.

Vermilion Flycatcher, Pyrocephalus rubinus, an immature male that excited the local birders since it’s a rare species in northern California:

Green Heron, Butorides virescens, casting a long shadow in an irrigation ditch:

Common Goldeneyes, Bucephala clangula, a group of females accompanied by one male lurking just out of sight:

Barrow’s Goldeneyes, Bucephala islandica, a more northerly species than the Common Goldeneye, distinguished by the female’s oranger beak and the male’s facial upside-down comma:

Osprey, Pandion haliaetus, watching for fish while also eyeing the humans watching it:

These two pictures are from Ashland, Oregon.

Oak Titmouse, Baeolophus inornatus, resembling Zippy the Pinhead:

Red-shouldered Hawk, Buteo lineatus, showing off a tessellated backside:

And the last is from Bodega Bay, California.

Belted Kingfisher, Megaceryle alcyon, my nearest thing to success at photographing this bold yet notoriously camera-averse bird: