rob mahurin

It may be that "the feels-like temperature is the same as the actual temperature" is a way to forestall questions about why the feels-like temperature is missing.

Oh look this is the same account that prompted me to make this illustration about light pillars.

A really stunning set of lunar halos here. Also some aurorae, and even a light pillar.

🔭

The student said, "A preposition is anywhere a mouse can go relative to a box. Above the box, inside the box, towards the box."

The master said, "The mouse *is* the box."

And the student was enlightened.

The best explanation I've encountered of "people feel heat flows, not temperature":

Imagine you are hiking on a chilly day and need to sit on an outdoor trailhead toilet. There are two options: wooden seat or metal seat. They're at the same temperature, but your experience will be very different.

Wind chill - Wikipedia

A nontrivial question with an interesting set of answers. People feel heat *flows*, rather than temperatures. There are several ways to normalize to "the way you would lose heat in still air at a different temperature." But it's unusual to report a 0.1⁰ difference.

There was a RadioLab several years ago about the sensation of beauty and behavioral or sexual natural selection — e.g. maybe we like landscapes because they're safe. One presenter said, "What if we like them because they're beautiful, and the usefulness is a side effect?" That sticks with me.

The summary suggests that we can distinguish between black holes made of mostly dark matter versus black holes made of mostly baryons. But wouldn't that break the "no-hair" restriction? Once anything crosses the event horizon, all that should be left is mass, angular momentum, and electric charge.

I think I linked all of the image sources in their own posts (though one is hidden in alt text). Let me know if I missed one.

Apologies again to the stranger who thought I was dressing them down; I was aiming for a "yes and" of interesting things.

A low sun, partially hidden by a tree trunk, is surrounded by crepuscular rays which appear to radiate in all directions. In front of the line of trees is dewy grass.

Sunlight shines through a line of trees, which cast glorious crepuscular ray shadows in the volume of the mist. One tree stands in front of some crepuscular rays and behind others. There's a colorful "ray" from the sun which is diffraction off of some smear on the camera lens.

The sunrise peeks through a treeline in the middle distance, across a dewy field. A sunbeam in the mist passes over the viewer's head, originating at the sun and appearing to propagate upward.

Cartoon showing a side view of crepuscular rays. A human figure in white stands on the right side of the frame, in a low place between two green hills. Parallel yellow diagonals suggest sunbeams coming diagonally down from the upper left. Some of these rays pass above the figure; these will appear to radiate "up" from the sun in that person's perspective.

Here on Earth, we can see the illusion of upgoing sunlight when the Sun is low. "Crepuscular rays" are columns of bright air running parallel to columns of shadowed air. Rays above or below the viewer converge towards the "vanishing point" at the sun.

[Foggy dawn photos and illustration by me.]

Mosaic of the Saturn system taken from within Saturn's shadow. Annotations indicate many objects, including the Earth-Moon system, Venus, several of Saturn's moons, and features of the rings. Source: https://ciclops.org/view/7699/The-Day-the-Earth-Smiled.html

Even from 30 a.u. away, where the Sun is 900 times dimmer than at Earth, cameras on space probes can be damaged by intense sunlight. This sunward mosaic was taken while Cassini was safely within Saturn's shadow.

Note the bright rim of the planet: that's every sunrise and sunset, planetwide.

Screenshot of a search for [face lit from below by flashlight], with a dozen-ish image results. The vibe is pretty spooky.

But why does the north-up "Saturn's underside" image look more natural than the south-up orientation? Well, "natural" is subjective. But here on Earth, light nearly always comes from above, and shadows happen on undersides. "Underlighting" feels unnatural and spooky.

Two images of the Earth and Moon taken from space probes at other planets, both on July 19, 2013. Left panel: Saturn's night side and rings loom at the top of the image, while a bright beam is visible about a third of the way from the bottom. An arrow indicates a pinpoint Earth center right. Caption: "View from Saturn (Cassini), 900 million miles away." Right panel: pinpoint Earth and smaller pinpoint Moon against a black background. Caption: "View from Mercury (MESSENGER), 61 million miles away."

In fact, you had your picture taken twice that day: once by the Cassini orbiter at Saturn, and once by the Messenger orbiter at Mercury.

This image is compressed differently than the one upthread, so you can see the Moon if you zoom in enough.

Source: apod.nasa.gov/apod/ap13072...

These images were taken on July 19, 2013, as part of a mosaic of images of Saturn's night side. If you were on Earth that day (including low Earth orbit), this is a picture of you!

This was only the third time that Earth had been imaged from the outer solar system.

Earth and Moon viewed by the Cassini orbiter from Saturn. Both are starlike, only a few pixels across against a dark and otherwise featureless sky. Earth, above left, is slightly brighter and noticeably bluer than the Moon, which has a yellowish hue.

[Note: this is an edited and expanded repost. The original quoted a stranger who wrote something like "Earth viewed from Saturn's underside." I was interested in the verticality illusion, but apparently it felt like a callout. Sorry, stranger.

Also, I missed the point: that's the Earth!]

Saturn's night side fills the upper left corner of the frame. The backlit rings stretch across the top of the image. A third of the way from the bottom, there is a soft beam of blue-white light, brighter on the left. A bright pinpoint, center-right, is Earth. If you were on or near Earth in July 2013, you're in this picture.

Saturn's night side fills the lower right corner of the frame. The backlit rings stretch across the bottom of the image. A third of the way from the top, there is a soft beam of blue-white light, brighter on the right. A bright pinpoint, center-left, is Earth. If you were on or near Earth in July 2013, you're in this picture.

Saturn's night side fills the lower left corner of the frame. The backlit rings stretch across the left of the image. A third of the way from the right, there is a soft vertical beam of blue-white light, brighter on the bottom. A bright pinpoint, center-top, is Earth. If you were on or near Earth in July 2013, you're in this picture.

Saturn doesn't have an "underside": this famous photo shows the winter hemisphere and the shadowed side of its rings. This image does happen to show the southern hemisphere, but that's an Earth convention. So why does the north-up "underside" photo look more natural than the others?

🔭🧵

Also stored on the other device: all of the alt-text.

DOUBLE DANG

My mobile browser is an up-to-date Firefox, running on Android.

I used my phone to draft a thread with a bunch of images, and when I hit "post all" it says "uploading images…" for a while and then reloads the page without posting.

I think it might work from a bigger computer, but the draft there says "Media stored on another device."

DANG

@support.bsky.team

Yes, beer is quantized.

Yeah. I tried to apologize for the misinterpretation and then the "thank you" disappeared.

I think I'm starting over since I also forgot the alt text.

Aw, dang, I also forgot to alt-text. Maybe I should just delete and repost.

Three logicians walk into a bar. The bartender says, "Do all you fellows want a beer?"

The first logician says, "I don't know."

The second says, "I don't know, either."

The third says, "Apparently, yes!"

Drat. I meant this to be an observation of an interesting illusion, but I'm afraid the author of the quoted post interpreted it as a callout. I'll want to phrase differently in the future.

It'll be interesting to see if the wrong-way illusion holds with only the rotated photo there.

Not the intended outcome, friend — I meant to observe the illusion, not to correct. Be well.

The Washington Post used to do their own reporting.

#bluesky #sunrise

I'm pretty sure that, after Libya publicly abandoned its WMD program, Qaddafi was dead in less than six months.

Ooooh, pareidolia

Humans get all excited about the ratio of birth canal to body size, but imagine giving birth to a tube that's five or ten babies across.

The science museum in Nashville has a bass violin set up next to a strobe light, so you can pluck a string and match the frequency. It's hard to see vibrations above about the fifth harmonic. (Though I think it's also not a terribly fast strobe.)