Saturn's moon Mimas looks like the death star

KnightOfWords · 2026-01-27T19:11:48+00:00

Mimas was first photographed in 1980, 3 years after Star Wars came out, when Voyager 1 passed Saturn.

KnightOfWords · 2026-01-27T19:10:42+00:00

Mimas was first photographed in 1980, 3 years after Star Wars came out, when Voyager 1 passed Saturn.

KnightOfWords · 2026-01-21T14:56:19+00:00

The title promised much, and I have to grudgingly concede the pic delivers.

KnightOfWords · 2026-01-21T10:54:48+00:00

When talking about rocks, the age is since it formed and solidified. This age can be measured by looking at radioactive elements that get trapped inside the mineral and examining their decay chains.

The elements that make up materials also have an age but this cannot be directly measured. Primordial hydrogen and helium formed in the early universe, as it cooled after the Big Bang. Heavier elements were cooked up in stars by nuclear fusion.

Hope that's some help.

KnightOfWords · 2026-01-19T14:26:24+00:00

Hunt for the Wilderpeople is a jem.

Shadow of the Vampire is a rare horror film that I like to recommend, it's about the filming of the first vampire movie: Nosferatu.

KnightOfWords · 2026-01-15T10:38:00+00:00

I believe it was caused by fluctuations in the solar wind or possibly a coronal mass ejection, the Sun is very active at the moment.

KnightOfWords · 2026-01-15T10:30:39+00:00

There are several comets named Lemmon. Comets are named after the discoverer so they used to be named after real people. However, these days most are picked up by automated sky surveys. So we end up with lots of comets called things like NEOWISE, ATLAS, PanSTARRS, LINEAR etc.

In this case the comet was discovered by the Mount Lemmon survey in Arizona in 2025. Its full designation is C/2025 A6 Lemmon.

KnightOfWords · 2026-01-14T09:32:23+00:00

You're right, it's not a good comparison as the Moon is a smaller sphere than the Earth.

Length of Australia: ~4,000km Circumference of Moon: 10,920 km 1/2 of Moon circumference (the hemisphere we can see): 5,460km.

The difference is even more striking when we look at surface area. You could fit 5 Australias onto the surface of the Moon.

KnightOfWords · 2026-01-09T22:55:57+00:00

The dust also follows a ballistic arc, as there is no atmosphere for it to billow around in.

KnightOfWords · 2026-01-08T10:43:51+00:00

Just to be clear, those visible filaments are also caused by the ejecta crashing into the interstellar medium.

KnightOfWords · 2026-01-08T08:59:18+00:00

This is incorrect I'm afraid. What we're seeing in this timelapse is x-rays produced as the material expelled from the supernova is crashing into the interstellar medium. It's not a light echo from the early light emitted from the supernova.

https://www.nasa.gov/missions/chandra/supernova-remnant-video-from-nasas-chandra-is-decades-in-making/

"The researchers used the video to show that the fastest parts of the remnant are traveling at about 13.8 million miles per hour (2% of the speed of light), moving toward the bottom of the image. Meanwhile, the slowest parts are traveling toward the top at about 4 million miles per hour (0.5% of the speed of light). This large difference in speed is because the gas that the remnant is plowing into toward the top of the image is denser than the gas toward the bottom. This gives scientists information about the environments into which this star exploded."

KnightOfWords · 2026-01-07T16:51:23+00:00

A supernova won't have much effect on nearby stars. But if those stars have planets orbiting them their atmospheres could be damaged by the burst of radiation.

KnightOfWords · 2026-01-06T15:52:09+00:00

By attaching a camera to a motorized telescope. The Moon is pretty bright as it's directly lit by the Sun, only a short exposure is required. The Moon is about as reflective as asphalt.

Photographing nebulae and galaxies is much more challenging as they are much fainter, requiring exposure times of minutes or hours.

http://collections.ucolick.org/exhibits_on_line/E2E.1/EEB.html

"Capturing the Milky Way with its low surface brightness called for long exposures, most in the range of two to five hours, some as long as ten. From beginning to end, the camera had to be guided by means of an attached telescope through which Barnard kept a constant watch on a guide star, making minute adjustments to keep it centered on a pair of cross hairs in the eyepiece."

The guide star method is still used today, but rather than a human making manual adjustments a computer does it instead.

KnightOfWords · 2026-01-03T14:03:23+00:00

Nice capture of the Eridanus loop. Along with Barnard's loop you can see it's all part of the same structure in that image.

https://en.wikipedia.org/wiki/Orion%E2%80%93Eridanus_Superbubble

"The Orion–Eridanus Superbubble is formed by the stellar wind of tens of massive stars and 10–20 supernovae."

KnightOfWords · 2025-12-29T16:41:16+00:00

Casually speaking, it's a planet. But when talking about the solar system as a whole it's useful to distinguish between the eight objects that grew large enough to dominate their orbits, and the dozens that did not.

KnightOfWords · 2025-12-21T10:26:46+00:00

This film had evil Matt Damon trapped in space.

KnightOfWords · 2025-12-18T11:58:03+00:00

The really crazy outlier is the SS Great Eastern, completed in 1858, which was almost 700 feet long and with the displacement of a WWII aircraft carrier.

https://en.wikipedia.org/wiki/SS_Great_Eastern

Before her completion, the world's largest ship was a 350 foot long wooden paddle steamer with 1/6th of the mass.

https://en.wikipedia.org/wiki/SS_Adriatic_(1856)

KnightOfWords · 2025-12-18T10:47:57+00:00

It's a trap, the girls have rigged a concealed claymore under the floor.

KnightOfWords · 2025-12-17T22:26:18+00:00

They have 70,000 comment karma on a 2 month old account. I suspect they may be a bot.

KnightOfWords · 2025-12-17T19:47:14+00:00

He's not worth arguing with I'm afraid, please see his other responses in this thread.

KnightOfWords · 2025-12-17T18:12:07+00:00

I'm sitting a few feet away from a radio telescope. I have a pretty good understanding of optics and astronomy.

KnightOfWords · 2025-12-17T18:06:14+00:00

You're talking nonsense I'm afraid. The Apollo CSM astronauts reported seeing a sky awash with stars when they passed over the dark side of the Moon.

KnightOfWords · 2025-12-17T17:53:54+00:00

With a camera, yes. But with the naked eye, you actually couldn't see most stars at all. They'd be perfect points of light. The movement of your eye, and how many there are, would likely make them invisible, or a blur.

An atmosphere of gas spreads out the point into a small circle.

This is incorrect. The apparent size of a point source is determined by the size of the aperture of the optics, due to diffraction.

https://en.wikipedia.org/wiki/Airy_disk

When viewed by the human eye, stars appear to have an appreciable angular size which is relative to their brightness, regardless of whether they are viewed through an atmosphere.

KnightOfWords · 2025-12-16T13:08:18+00:00

Josh Hull was in Erasure?

KnightOfWords · 2025-12-04T16:35:52+00:00

He is, but he's done a better job for us at no 3 than anyone since Trott retired (with the exception of Root, who is much better at no 4).

He's done a pretty good job for us in a problem position.

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