Talk:Hubble Ultra-Deep Field

diameter

The patch of sky in which the galaxies reside (just one-tenth the diameter of the full moon) [...]. The "diameter" depends on how far away you are from the object observed. Giving a arcsecond number as the Hubble Deep Field article does ([The Hubble Deep Field photo] covers an area 144 arcseconds across, equivalent in angular size to a tennis ball at a distance of 100 metres.) is more precise. --Abdull 08:59, 25 April 2006 (UTC)

Sounds good to me. Most people are on the earth when they look at the moon, giving a distance of about 400,000km. I think the moon measurement is worth keeping in too as most people don't know what an arcsecond is, though the tennis ball analogy is also good. Stephen B Streater 16:39, 25 April 2006 (UTC)

I just added the phrase "as viewed from Earth" after "diameter of the full moon", which I think keeps it tied to a common reference (á la Stephen B Streater's point) but also making it technically accurate. Ryan McDaniel 20:02, 25 April 2006 (UTC)

...looking back in time more than 13 billion light years. This doesn't seem correct. A light year is a measure of distance, not time. Does the author actually mean "13 billion years"?Frankwomble 18:35, 25 April 2006 (UTC)

Yes - but then isn't the Universe around 13 billion years old? Perhaps it's nearer to 14 Bn. Stephen B Streater 19:57, 25 April 2006 (UTC)

Technically, one could make the nitpicking argument that they're equivalent, since the Hubble is looking at light, which does, after all, travel one light-year in a year. However, it is confusing; I've changed it to "years". Ryan McDaniel 20:02, 25 April 2006 (UTC)

The latest official age of the universe is around 13.7 billion years old. This information is in the latest edition of the Astronomy for Dummies. --Siva1979^{Talk to me} 20:24, 25 April 2006 (UTC)

3 arcminutes square is ambiguous. Does it mean 3 square arcminutes, as in 1.732 arcminutes per side, or does it mean 9 square arcminutes, as in 3 arcminutes per side? --76.209.59.227 06:33, 20 January 2007 (UTC)

Category: Aminov Images

I capitalized this category listing (was "aminov images"), but neither category exists. What are "aminov images", and what's the reason for putting the HUDF in this category? Ryan McDaniel 20:02, 25 April 2006 (UTC)

Slight confusion?

Okay so I'm a little confused, is the image of an area of sky the size of 1/10th of the moon... or is it an image of the sky less than a spec of sand held at arms length?

Everytime i re-read the article my conclusion differs from the last, can someone clear this up please? Thanks Stevey^ 16:11, 8 June 2006 (UTC)

Remember it is a tenth of the diameter of the full moon - that's a hundredth of the area of the full moon. Also because of optical illusion, the full moon appears larger than it actually is (half a degree diameter) - at arm's length (about 70 cm), an object 6 mm diameter (about the size of a small pea) would cover the moon. An object 0.6 mm diameter would cover the HUDF pic, and yes, that's about the size of a grain of sand. - MPF 21:22, 8 June 2006 (UTC)

Are you eight years old, MPF? It's considerably more than 70 cm for an adult. For generations, drygoods merchants have been measuring yard goods by the distance from their nose to their thumb and forefinger clenched together. The moon (or the sun - they are almost the same size - is the size of a dime held at arm's length - and that's 17.91 mm. A diameter of 1.79 mm is considerably bigger than a grain of sand; it's almost as big as a small peppercorn. ClairSamoht - Help make Wikipedia the most authoritative source of information in the world 21:30, 28 September 2006 (UTC)

Oh yeah, that's all clear now, so it's the size of a pomegranete seed resting on a mouses head a hogshead away from an elbow.83.70.248.72 18:02, 23 May 2007 (UTC)

Macroevolution

While reading this article, I have noticed excessive presentation of the unproven theory of macroevolution as fact in such phrases as "..existing when the universe was just 800 million years old." As this is not proven fact, I request that all macroevolution content be removed from this article, or at least stated as theory. Yurimxpxman 19:25, 11 January 2007 (UTC)

Forgive my ignorance, but what does macroevolution ("evolution that occurs at or above the level of species") have to do with the age of the universe? Cedlaod 04:22, 13 February 2007 (UTC)

Cedlaod, I think we're dealing with a creationist. Anyway, this is a cosmology-related article, and it's based on the principles of Cosmology. That quotation is based on currently accepted cosmological science. Jolb 22:42, 1 March 2007 (UTC)

Yurimxpxman, you don't seem to understand what "theory" means in scientific jargon. You're right, macroevolution is not a proven fact, but a valid scientific theory that withstands substantial evidence. From such a theory, facts are concluded based on the evidence. If you will, theories are higher than facts, as they not only explain but produce knowledge. Now, unfortunately for Young Earth Creationism, astronomical theory allows us to conclude that stars are (with insignificant doubt) millions of light years away, and as elementary optics show, it takes millions of years for the light to reach Earth. Therefore the universe is almost definitely at least millions of years old. Now, understanding that, understand in cosmology, dedicated scientists have given a huge amount of effort to produce facts, and through their theoretical findings combined with astronomical data and evidence, including Cosmic microwave background radiation and redshift it appears that the universe is almost definitely billions of years old. That, my friend, is how scientific theory "proves" things, and is why the article should stand as written. 128.253.97.189 (talk) 02:35, 18 September 2008 (UTC)

Sources

This article doesn't cite many sources. See featured articles (e.g. Hubble_Space_Telescope) to see how this is done. Rnt20 09:22, 20 January 2007 (UTC)

Next One?

Any idea when they might do another one of these? How much telescope time does it take up? --Cngodles 16:24, 6 March 2007 (UTC)

It took 4 months to complete all the exposures. No idea if or when they'll do another one, but according to the article, they'd all look pretty much the same anyway. - Tronno ( t | c ) 03:35, 22 March 2007 (UTC)

Actually, I think another one will probably be done once Hubble is serviced next year. No deep imaging can be done before then, for two reasons. Firstly the ACS is broken and the only currently working alternative is the WFPC2, which has a much smaller field of view and has already been used to capture the HDF and HDF South. Secondly, Hubble is limping on failing gyros, if you started observing now there's no guarantee the HST wouldn't break before you finished! Although the HUDF took 4 months, that was only 4 months of Directors Discretionary Time (about 10% of the total telescope time), which translates to less about 2 weeks solid observing. Yes, that's a lot, but not beyond reason.

Now, the only reasons for more of these deep images are to go back further (ie deeper) and to test the cosmological principle. As has been noted, the three HST deep images look pretty much the same, which is great for the principle. However, we can still go back further, but to do so requires either more exposure time or a more sensitive instrument. The HUDF was motivated mostly because of the (then) new ACS instrument, which was more sensitive and offered a larger field of view than WFPC2. I don't know any details, but my guess is WFC3 (to be installed in the servicing mission) will be even more sensitive. Since the installation of the ACS was followed 18 months later by the HUDF, and since the servicing mission will also fix the gyros, it's my guess that a year or so after the servicing mission a new deep image will be taken (may called the HXDF, for extreme?). Anyone at STSci want to disillusion me? Modest Genius ^talk 23:16, 24 April 2007 (UTC)

uh, math error?

The article reads:

"It is the deepest image of the universe ever taken in visible light, looking back (to when the universe is thought to have been 800 million years old) more than 13 billion years ago."

if the other articles say that the universe is 3.7 billion years old, shouldn't this read almost 13 billion years old. 13.7 - 0.8 = 12.9

or is the 120 million year possible error taken into account here.. —Preceding unsigned comment added by 74.78.112.107 (talk) 04:31, 12 June 2008 (UTC)

The HUDF reveals galaxies that existed as early as just 400 million years after the big bang. But the image also shows much younger galaxies. It is not a simple snapshot of one particular time in the history of the universe. See this diagram. The HUDF shows objects from 400 million years old and yougner, while the HDF shows objects from 1 billion years ago and younger. The purpose of the HUDF is to study galaxies during the time from about 400 ~ 800 million years after the big bang. --mikeu ^talk 13:56, 2 October 2008 (UTC)

Citations!

took out the last paragraph as it had no sources at all. hope this is ok, it makes it look bad with 'citation needed' all over the place. —Preceding unsigned comment added by 62.31.160.221 (talk) 02:11, 17 August 2008 (UTC)

ref

The HUDF is actually two images, one visible and the other infrared. (The image in the article is the visible light image taken with the ACS. The infrared image can be found at http://hubblesite.org/newscenter/archive/releases/2004/07/image/b/ but I'm not sure if it is on commons yet.) "The combination of ACS and NICMOS images will be used to search for galaxies that existed between 400 and 800 million years... after the big bang." will fix the citation needed but the article will need to be reworded. I'll try to work this into the article next week when I have more time. --mikeu ^talk 13:16, 2 October 2008 (UTC)