## Cool astronomy photos

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Witness
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### Re: Cool astronomy photos

Supersharp images from new VLT adaptive optics

ESO's Very Large Telescope (VLT) has achieved first light with a new adaptive optics mode called laser tomography -- and has captured remarkably sharp test images of the planet Neptune and other objects. The MUSE instrument working with the GALACSI adaptive optics module, can now use this new technique to correct for turbulence at different altitudes in the atmosphere. It is now possible to capture images from the ground at visible wavelengths that are sharper than those from the NASA/ESA Hubble Space Telescope.
https://www.sciencedaily.com/releases/2 ... 082220.htm

This image of the planet Neptune was obtained during the testing of the Narrow-Field adaptive optics mode of the MUSE/GALACSI instrument on ESO's Very Large Telescope. The corrected image is sharper than a comparable image from the NASA/ESA Hubble Space Telescope.
Hubble image for comparison:

http://hubblesite.org/images/news/69-neptune

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### Re: Cool astronomy photos

If anyone is interested:

Why NASA is struggling to get its most powerful space telescope off the ground
NASA has long been plagued by critically underestimating spacecraft costs. The Hubble Space Telescope, initially projected to cost $200 million, wound up costing$1.2 billion to develop. After, its mirror required multiple fixes, which racked up billions more in expenses. A recent report from NASA’s inspector general identified a culprit of NASA’s chronic underestimation: a culture of optimism. He noted that NASA does not consider meeting cost and schedule deadlines as a measure of success and that the agency expects more money to be provided if projects go over budget. That has certainly been the case for JWST, which has continued to receive funding as its costs increase. Congress capped the development budget at \$8 billion, but lawmakers are still expected to fund the telescope’s new budget overruns. The space agency is also incentivized to low-ball on price when presenting projects to Congress, making them much more appealing at first blush.
"A culture of optimism" or more cynically, a culture that understands that you intentionally low-ball the estimate so that you can get approval to start the project and then count on the fact that you can go back to get more money later when the inevitable cost overruns occur.
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### Re: Cool astronomy photos

APOD wrote:What wonders lie at the center of our Galaxy? In Jules Verne's science fiction classic A Journey to the Center of the Earth, Professor Liedenbrock and his fellow explorers encounter many strange and exciting wonders. Astronomers already know of some of the bizarre objects that exist at our Galactic center, including like vast cosmic dust clouds, bright star clusters, swirling rings of gas, and even a supermassive black hole. Much of the Galactic Center is shielded from our view in visible light by the intervening dust and gas, but it can be explored using other forms of electromagnetic radiation. The featured video is actually a digital zoom into the Milky Way's center which starts by utilizing visible light images from the Digitized Sky Survey. As the movie proceeds, the light shown shifts to dust-penetrating infrared and highlights gas clouds that were recently discovered in 2013 to be falling toward central black hole. In 2018 May, observations of a star passing near the Milky Way's central black hole showed, for the first time, a gravitational redshift of the star's light -- as expected from Einstein's general relativity.
https://apod.nasa.gov/apod/ap180729.html

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### Re: Cool astronomy photos

Witness
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### Re: Cool astronomy photos

Went out on the balcony and immediately saw a meteor, even with unadapted eyes.

So perhaps you should have a look. Interactive details: https://www.timeanddate.com/astronomy/m ... rseid.html.

Good luck!

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### Re: Cool astronomy photos

Just waiting for it to get dark here....
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### Re: Cool astronomy photos

Olympus Mons on Mars. ~ 25 km high.

Anaxagoras
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### Re: Cool astronomy photos

The air must be really thin up there.

I know, the air is thin on mars even on the lowlands. But Everest is what, 9 km high, and the air pressure is about a third of what it is at sea level. Also there's no such thing as "sea level" on mars.
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### Re: Cool astronomy photos

Wrong: It could be computed from accurate enough topographic maps. Sure, not 'sea level', but rather, 'sand level'?
You can lead them to knowledge, but you can't make them think.

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### Re: Cool astronomy photos

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### Re: Cool astronomy photos

HONK!

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### Re: Cool astronomy photos

HONK!!!
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### Re: Cool astronomy photos

sparks wrote:
Mon Aug 20, 2018 5:56 pm
Wrong: It could be computed from accurate enough topographic maps. Sure, not 'sea level', but rather, 'sand level'?
"Sand level" is not "sea level" though, is it?

Think about it for a moment: Imagine there is no water on earth (and never mind the pesky problems that would arise from that, this is a thought experiment). How do you calculate altitude? What do you use as your point of reference? The lowest point? The average of all points? It can't be "sea level" without a sea.
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Doctor X
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### Re: Cool astronomy photos

Actually, I thought of that. I mean, what do you do with the Marianas Trench if the Earth had no water?

You would have to figure out a reasonable level. I guess one could consider what is a sort of mean level removing the outliers of mountains or trenches, or you could just stare at Pluto's moon:

--J.D.

P.S. Yes . . . yes . . . YES . . . you want Pluto to enter Ura[Stop that!--Ed.]th tentacles.
Mob of the Mean: Free beanie, cattle-prod and Charley Fan Club!
"Doctor X is just treating you the way he treats everyone--as subhuman crap too dumb to breathe in after you breathe out."--Don
DocX: FTW.--sparks
"Doctor X wins again."--Pyrrho
"Never sorry to make a racist Fucktard cry."--His Humble MagNIfIcence
"It was the criticisms of Doc X, actually, that let me see more clearly how far the hypocrisy had gone."--clarsct
"I'd leave it up to Doctor X who has been a benevolent tyrant so far."--Grammatron
"Indeed you are a river to your people.
Shit. That's going to end up in your sig."--Pyrrho
"Try a twelve step program and accept Doctor X as your High Power."--asthmatic camel
"just like Doc X said." --gnome

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### Re: Cool astronomy photos

Anaxagoras wrote:
Tue Aug 21, 2018 6:45 am
sparks wrote:
Mon Aug 20, 2018 5:56 pm
Wrong: It could be computed from accurate enough topographic maps. Sure, not 'sea level', but rather, 'sand level'?
"Sand level" is not "sea level" though, is it?

Think about it for a moment: Imagine there is no water on earth (and never mind the pesky problems that would arise from that, this is a thought experiment). How do you calculate altitude? What do you use as your point of reference? The lowest point? The average of all points? It can't be "sea level" without a sea.
sparks is right (once more – can't fool the engineer ).

"Sea level" is a fickle concept. You can measure it locally (mean between high and low tide) or, as does the GPS, use a theoretical ellipsoid (which can be off by up to 100 m to the physical water surface).
This small graph explains it well (extracted from: https://en.wikipedia.org/wiki/Sea_level):

(Geoid is just ellipsoid + major bumps.)

Now Mars has been mapped very precisely by the MOLA (Mars Orbiter Laser Altimeter) – notice the "altimeter", it's a height map – and the mean height set at the mean equatorial radius.

And NASA uses its various probes' trajectories to test the gravitational field around the planet:

More maps & explanations: https://svs.gsfc.nasa.gov/4436

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### Re: Cool astronomy photos

Nevertheless, the concept of "sea level" (narrowly defined) does not apply on Mars.

It also depends on the amount of water on a given planet. If the earth had more water, or less water, the sea level would be different. I think my original statement stands. I didn't say that you can't measure altitude on Mars, merely that you cannot use "sea level" as a reference level from which to measure it.
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### Re: Cool astronomy photos

They found water on Mars, Anax . . .

You claiming that she is not on the level?

Of course, you seeing only White prefer:
--J.D.
Mob of the Mean: Free beanie, cattle-prod and Charley Fan Club!
"Doctor X is just treating you the way he treats everyone--as subhuman crap too dumb to breathe in after you breathe out."--Don
DocX: FTW.--sparks
"Doctor X wins again."--Pyrrho
"Never sorry to make a racist Fucktard cry."--His Humble MagNIfIcence
"It was the criticisms of Doc X, actually, that let me see more clearly how far the hypocrisy had gone."--clarsct
"I'd leave it up to Doctor X who has been a benevolent tyrant so far."--Grammatron
"Indeed you are a river to your people.
Shit. That's going to end up in your sig."--Pyrrho
"Try a twelve step program and accept Doctor X as your High Power."--asthmatic camel
"just like Doc X said." --gnome

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Witness
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### Re: Cool astronomy photos

Anaxagoras wrote:
Wed Aug 22, 2018 3:56 am
Nevertheless, the concept of "sea level" (narrowly defined) does not apply on Mars.
I of course agree with that!

Anaxagoras wrote:
Wed Aug 22, 2018 3:56 am
It also depends on the amount of water on a given planet. If the earth had more water, or less water, the sea level would be different. I think my original statement stands. I didn't say that you can't measure altitude on Mars, merely that you cannot use "sea level" as a reference level from which to measure it.
Perhaps we can agree on "virtual sea level" on Mars?

But, as I stressed, "sea level" varies in space and time on various scales, so it's already a kind of fiction.

Especially now that we can fix positions to centimeter scale with survey grade GPS (millimeter with hours of data collecting + post-processing).

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### Re: Cool astronomy photos

NASA's Cassini spacecraft captured this image of the Saturn moons Titan (foreground) and Tethys on Nov. 26, 2009.

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### Re: Cool astronomy photos

Witness wrote:
Thu Aug 23, 2018 4:25 am
Anaxagoras wrote:
Wed Aug 22, 2018 3:56 am
Nevertheless, the concept of "sea level" (narrowly defined) does not apply on Mars.
I of course agree with that!

Anaxagoras wrote:
Wed Aug 22, 2018 3:56 am
It also depends on the amount of water on a given planet. If the earth had more water, or less water, the sea level would be different. I think my original statement stands. I didn't say that you can't measure altitude on Mars, merely that you cannot use "sea level" as a reference level from which to measure it.
Perhaps we can agree on "virtual sea level" on Mars?

But, as I stressed, "sea level" varies in space and time on various scales, so it's already a kind of fiction.

Especially now that we can fix positions to centimeter scale with survey grade GPS (millimeter with hours of data collecting + post-processing).
Call it average ground level, or mean ground level, what ever you like best. It's best use would be to establish (as Witness pointed out) an average (as our oceans more or less do for us on Earth) that we might then measure other beasties against that. But I rather think someone has already thought of this. How else could one say how high Mons Olympus is? For the purposes of landing things on the Red planet, radar ranging is still going to be a necessity and I think the same might be said of flying things over the Red planet. We'd certainly want to know if we were about to auger in after all.

I presume properly sensitive altimeters might be employed...
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