Cool astronomy photos

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Bruce
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Re: Cool astronomy photos

Post by Bruce »

It can be a bit hard to win a you mama contest with a astrophysicist.

You mama so fat, she has her own event horizon. Don't feel bad though. You're daddy left a long time ago, but there's still an anti-daddy somewhere inside yo mama.
Such potential!

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Witness
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Re: Cool astronomy photos

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sparks wrote:
Thu Dec 05, 2019 2:28 am
How is it that something is massive enough to sustain fusion can be smaller than the earth?
They don't sustain fusion (powered by gravity, the most efficient process known) but are still stars. Sirius B is a roughly Earth-sized white dwarf.

As for True Stars™, here's a 2017 article:
Astronomers just discovered the smallest star ever

While on the search for exoplanets, the team came across this tiny companion.

Image

A team of astronomers at the University of Cambridge was on the lookout for new exoplanets when they came across an exciting accidental discovery: They found the smallest star measured to this day.

This tiny new star, which is being called EBLM J0555-57Ab, is about 600 light-years from Earth, and has a comparable mass (85 Jupiter masses) to the estimated mass of TRAPPST-1. The new star, though, has a radius about 30 percent smaller. Like TRAPPIST-1, EBLM J0555-57Ab is likely an ultracool M-dwarf star.

The team used data from an experiment called WASP (the Wide Angle Search for Planets), which is typically used in the search for planets rather than stars, to look for new exoplanets. During their studies, they noticed a consistent dimming of EBLM J0555-57Ab’s parent star, which signified an object in orbit. Through further research to measure the mass of any orbiting companions, they discovered the object they’d detected was too massive to be a planet — it was instead a tiny star.

Though EBLM J0555-57Ab is incredibly small, it still has enough mass for hydrogen fusion, which powers the Sun and makes it Earth’s energy source. Just barely bigger than Saturn, the star has a gravitational pull 300 times stronger than Earth’s. If the star were much smaller (about 83 Jupiter masses), there wouldn’t be enough pressure in its center for the process to occur, and it would instead have formed as a brown dwarf, rather than a true star.
http://astronomy.com/news/2017/07/tiny-new-star

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sparks
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Re: Cool astronomy photos

Post by sparks »

Well, there we are then: A body has to be a bit more massive than Jupiter, and about the same size to sustain fusion.
You can lead them to knowledge, but you can't make them think.

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Witness
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Re: Cool astronomy photos

Post by Witness »

> 83 Jupiter masses.

Jupiter generates some heat, but it's thought it is the helium "falling" (slowly) to the center.

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sparks
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Re: Cool astronomy photos

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I've read in older books that the mass difference would only have to have been 3 Jupiter masses. They've obviously revised this upwards.
You can lead them to knowledge, but you can't make them think.

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Fid
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Re: Cool astronomy photos

Post by Fid »

You know of course Bruce's employment has him chained in a non-Einstein...ish universe. One in which that jolly tale of an automobile wreck never happened?
Be nice dammit!
... The stars were suns, but so far away they were just little points of light ... The scale of the universe suddenly opened up to me. It was a kind of religious experience. There was a magnificence to it, a grandeur, a scale which has never left me. Never ever left me.
Carl Sagan

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sparks
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Re: Cool astronomy photos

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I see your point ... I think. :)
You can lead them to knowledge, but you can't make them think.

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Witness
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Re: Cool astronomy photos

Post by Witness »

If we can believe Wikipedia:
With a mass only 93 times that of Jupiter (MJ), or .09 M☉, AB Doradus C, a companion to AB Doradus A, is the smallest known star undergoing nuclear fusion in its core.[9] For stars with similar metallicity to the Sun, the theoretical minimum mass the star can have, and still undergo fusion at the core, is estimated to be about 75 MJ.[10][11] When the metallicity is very low, however, a recent study of the faintest stars found that the minimum star size seems to be about 8.3% of the solar mass, or about 87 MJ.[11][12] Smaller bodies are called brown dwarfs, which occupy a poorly defined grey area between stars and gas giants.

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Anaxagoras
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Re: Cool astronomy photos

Post by Anaxagoras »

sparks wrote:
Wed Dec 04, 2019 2:52 pm
I was under the mistaken impression that our Sun was about as small as a star could get and still maintain nuclear fusion. :? :?

And if there are stars smaller than Earth, why didn't Jupiter and Saturn ignite long ago?
Actually I think our sun is kind of a medium-sized star. Red dwarfs like Proxima Centauri are definitely a lot smaller than our sun, and orange dwarfs are bigger than red dwarfs but smaller than our sun (which is called a yellow dwarf). Red dwarfs just a little bit bigger than Jupiter can maintain nuclear fusion. The really small ones about earth-size are white dwarfs, which is what's left after a medium-sized star like our sun reaches the end of its life and goes nova. Before that happens it will turn into a red giant and swell up to a size big enough to engulf Mercury, Venus and probably Earth too. That stage will last for a few million years until it finally runs out of fuel and collapses before exploding in a nova.
A fool thinks himself to be wise, but a wise man knows himself to be a fool.
William Shakespeare

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Witness
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Re: Cool astronomy photos

Post by Witness »

Slow going, but worth a peek:



So much water!

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Fid
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Re: Cool astronomy photos

Post by Fid »

Even with the time compression and fish eye lens distortion that was awesome.

A bit ago there was installed an external high def video experiment on the ISS. The feed failed after a couple years but boy howdy while it lasted!

Thank you.
... The stars were suns, but so far away they were just little points of light ... The scale of the universe suddenly opened up to me. It was a kind of religious experience. There was a magnificence to it, a grandeur, a scale which has never left me. Never ever left me.
Carl Sagan

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Witness
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Re: Cool astronomy photos

Post by Witness »

Image

A real photo from a real spacecraft. :)

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Fid
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Re: Cool astronomy photos

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Naa, fake pic by NASA stooges to pretend comets/asteroids exist which by tortured reasoning means the Earth ain't flat and "space" actually exists.
... The stars were suns, but so far away they were just little points of light ... The scale of the universe suddenly opened up to me. It was a kind of religious experience. There was a magnificence to it, a grandeur, a scale which has never left me. Never ever left me.
Carl Sagan

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Witness
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Re: Cool astronomy photos

Post by Witness »

Fid wrote:
Fri Dec 06, 2019 2:41 am
A bit ago there was installed an external high def video experiment on the ISS. The feed failed after a couple years but boy howdy while it lasted!
There's still an ISS live feed:



But they could get rid of the junk at the bottom and just put the map in a corner. :|

Fid wrote:
Fri Dec 06, 2019 2:41 am
Thank you.
My pleasure. :)

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Witness
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Re: Cool astronomy photos

Post by Witness »

Searching for a good Moon video on YT I was quite astonished by the sheer quantity of woo-woo our humble satellite seems to attract. Especially round craters ==> flat Earth. :?

But I found this pleasant flyby with some science thrown in:



The blurb:
In the fall of 2011, the Lunar Reconnaissance Orbiter (LRO) mission released its original Tour of the Moon, a five-minute animation that takes the viewer on a virtual tour of our nearest neighbor in space. Six years later, the tour has been recreated in eye-popping 4K resolution, using the same camera path and drawing from the vastly expanded data trove collected by LRO in the intervening years. The tour visits a number of interesting sites chosen to illustrate a variety of lunar terrain features. Some are on the near side and are familiar to both professional and amateur observers on Earth, while others can only be seen clearly from space. Some are large and old (Orientale, South Pole-Aitken), others are smaller and younger (Tycho, Aristarchus). Constantly shadowed areas near the poles are hard to photograph but easier to measure with altimetry, while several of the Apollo landing sites, all relatively near the equator, have been imaged at resolutions as high as 25 centimeters (10 inches) per pixel.
The new tour highlights the mineral composition of the Aristarchus plateau, evidence for surface water ice in certain spots near the south pole, and the mapping of gravity in and around the Orientale basin.
The camera flies over the lunar terrain, coming in for close looks at a variety of interesting sites and some of the LRO data associated with them. Includes feature titles, research sources, and the location and scale of the image center.
Video downloadable, link on YT.

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Fid
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Re: Cool astronomy photos

Post by Fid »

Using the overworked word that was "awesome".

Who knew all these years of looking at Tycho telescopically there was a big honkin' rock perched on the central peak.
... The stars were suns, but so far away they were just little points of light ... The scale of the universe suddenly opened up to me. It was a kind of religious experience. There was a magnificence to it, a grandeur, a scale which has never left me. Never ever left me.
Carl Sagan

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Witness
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Re: Cool astronomy photos

Post by Witness »

Mars panoramas:


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Witness
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Re: Cool astronomy photos

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Rob Lister
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Re: Cool astronomy photos

Post by Rob Lister »

That little sperm was moving!

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sparks
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Re: Cool astronomy photos

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Egg destroyed.

Mission accomplished.
You can lead them to knowledge, but you can't make them think.