Hubble Snaps Photo Of A Galaxy's Edge

Adam Attarian writes: "Some really cool stuff is coming out of that telescope in the sky. Take a look at this. That's Galaxy NGC 4013, as never seen before. CNN has the story here. Viewing the galaxy from the side showed a large density of intersteller dust, resulting in a large black lateral band. Quite the site!" This is an amazing picture.

Comments

Astronomy Picture of the Day

[OlympcSponsor]

For fans of these kinds of pictures, Astronomy Picture of the Day is hard to beat. They have a this same picure for today.
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Re:Astronomy Picture of the Day

[Black Parrot]

> They have a this same picure for today.

For today's today (01-March) they have a way-cool pic of the sun.

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Okay, I've got a question

[Skyshadow]

I saw some program on the Discovery Channel a while ago that new software in ground-based telescopes using adaptive optics allowed them to more or less completely filter out the effects of the atmosphere.

Given that, they should easily be superior to the Hubble, since they have larger mirrors, right?

Then why are all of the really cool pictures of space crap from the freakin' Hubble? Is it a PR thing, trying to justify the cost of a space telescope when the ground 'scopes actually do a better job now? Or did the Discovery Channel (gasp!) misinform me?

Obviously, I'm not an astronomer. Obviously, one of you must be. Help me out.

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Re:Okay, I've got a question

[Black Parrot]

> I saw some program on the Discovery Channel a while ago that new software in ground-based telescopes using adaptive optics allowed them to more or less completely filter out the effects of the atmosphere.

The March Scientific American had an article about interferometry in the visual spectrum, and by using it they're starting to get ground-based photos that resolve close binaries and even show the limb darkening on stellar disks. Cool stuff, and more on the way.

> Is it a PR thing, trying to justify the cost of a space telescope when the ground 'scopes actually do a better job now?

IANATelescopeEngineer, but it seems that the Hubble does still have an advantage in certain areas. For instance, the methods described in the article I mentioned above suffer because they can't collect very much light. Presumably the Hubble still has a slight edge in various aspects of telescopy.

Also, remember that ground-based telescopy has enjoyed a generation of progress since the Hubble was designed, so it stands to reason that the Hubble's advantages would be fading and will soon be cancelled altogether.

It's still giving the coolest pix, though.

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Re:Okay, I've got a question

[Elbelow]

I am not an astronomer either, but I did watch a BBC Horizon documentary on the construction, failure and repair of the Hubble Space Telescope yesterday evening (sadly, the transcript is not available anymore, it appears). The Hubble has two advantages: no image distortion due to turbulence in the atmosphere, and the ability to detect light frequencies that are completely filtered out by the atmosphere (ultraviolet and infrared, amongst others). Ground-based telescopes are indeed catching up in the first area, but they still can't detect light that never reaches them. Of course, plans are already being made for the Next Generation Space Telescope, which will have an eight-meter mirror.

Re:Okay, I've got a question

[Royster]

Also, remember that ground-based telescopy has enjoyed a generation of progress since the Hubble was designed, so it stands to reason that the Hubble's advantages would be fading and will soon be cancelled altogether.

Old telescopes that are no longer state of the art continue to do important astronomical work. The Palomar Telescope, for example, continues to do important work on asteroids. It's just not as sexy as the stuff that hits the news outlets.

Re:Okay, I've got a question

[Puk]

This doesn't completely answer your question, but I found this quote in this article, linked from the Astronomy Picture of the Day, which was linked to above by some kind soul.

The Hubble Space Telescope reigns supreme for taking crisp photographs of faint objects, but ground-based optical interferometers can see, for the brightest stars, details 100 times finer than Hubble can.

I guess this means that hubble is better only at getting faint objects (which are, perhaps, nearly completely filtered out by our atmosphere, or at least enough to make interferometry ineffective. Meanwhile, bright objects gain enough resolution from these techniques to have surpassed what hubble has gained in super-atmospheric location.

Next step -- large-mirrored space-bound telescopes using interferometry techniques. If they don't cut NASA's budget too much. :)

-Puk

Re:Okay, I've got a question

[bph]

FWIW, I am an Astronomer.

Ground based Adaptive Optics currently does not produce very many pretty pictures. There are basically a number of technical reasons why, some of which will be ironed out in the short term and some of which will take a long time to solve (and involve things like batteries of lasers, which makes me think I will stop doing astronomy and start doing laser engineering if I am not careful.)

Anyway, for a cool adaptive optics astro pic done by people where I work, look here for Neptune and here for the moons of Jupiter. For some stars, and other cool stuff, check out this image of the galactic center.

Stars and planets are much easier with adaptive optics than are galaxies, though my housemate does galaxies wtih AO, because whenever you correct for atmospheric distortion, you never do a perfect job. The part of the beam of light that is not corrected can throw light all over your image. This means, if your object is not bright, a bright nearby thing could swamped it. And, in order to get adaptive optics to work, you have to have a bright nearby object to correct your image with. The solution is better adaptive optics systems, so for the mean time, Hubble will continue to surpass ground telescopes for image quality.

Re:Okay, I've got a question

[PD]

To add to what you said...

Adaptive optics are limited right now by computation, and sensing technology. We know how to correct a wavefront over a 10, 20, or even 50 meter mirror (those are planned) but the computers required to do the job just don't exist yet.

Secondly, infrared wavelengths pass through interstellar dust much better than longer visible wavelengths. There's a lot of interesting stuff that's hidden inside of dust clouds, so that's what wavelengths astronomers want to use.

Water vapor in the atmosphere absorbs infrared light, even at the best locations. Space born telescopes don't have this problem. Hubble has got some pretty good infrared sensors on board.

Same deal with UV, XRays and gamma rays. The atmosphere absorbs those wavelengths, so once again you've got to get above the air.

Radio telescopes don't have that problem but they are susceptible to interference from other radio sources. The far side of the moon would be a great place for a radio telescope.

Re:What a Fucken Waste of Tax $

[Black Parrot]

> It's easy to tell where the priorities of Bush and Cheney are, that being defense spending and giving large tax cuts

The increased military spending is just another kind of handout. Remember that a few years ago the US Congress approved a defense budget containing billions of dollars for projects that weren't even on the Pentagon's wish list.

All that money goes somewhere, very much of it to defense contractors. Usually those defense contractors are in one of the committee members' home town. The projects get approved because they pour money into the hands of a legislator's cronies back home, and the legislator benefits because the folk back home like the jobs and increased standard of living... to say nothing of the kickbacks^w campaign donations from the companies that got the money.

It shouldn't be any surprise that the current administration is wringing their hands about how negelected the military is. It's just a codeword for how neglected the defense contractors are.

Fasten your seatbelts; we're in it for Regan Era II.

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