The structure of astronomical objects reveals much about their history of formation which, because of the inherently very long "astronomical" timescales, cannot be directly observed. This million pixel digital camera was installed at the 2. Following initial, purely technical tests, a subsequent Scientific Verification Phase was devoted to exploring in depth the exceptional research capabilities of this new facility.
Several early, spectacular WFI pictures of mostly single, large objects have been published previously. As an important service to the ESO users community, the EIS Team has already released several atlasses, as well as catalogues with many thousands of objects. Various, particularly long and deep exposures were obtained during Science Verification and the routine operations phase.
They demonstrate both the capabilities of the WFI and the stunning richness and splendor of the deep Universe. From the available data, three sky areas have been selected and are shown here as examples of what is now possible with the WFI : the AXAF Deep Field , a field in the Milky Way "Zone of Avoidance" in the general direction of the "Great Attractor" , and Abell , a rich cluster of galaxies. There is very little interstellar neutral hydrogen gas within the Milky Way in this direction, ensuring a clear view towards the distant Universe a much less favourable direction is shown on ESO Press Photos eso c-e.
The field is crowded with faint and distant galaxies. ESO Press Photo eso a was obtained in blue light B-filter only and shows one of the largest numbers of galaxies ever observed in a single field.
One, No One and One Hundred Thousand | U67
Advanced image processing software was used to find, classify and count the objects in this field. As expected, most of the brighter, small sources turned out to be foreground stars in the Milky Way. However, because the stars in the Milky Way Galaxy are essentially confined to a relatively thin disk and this line of sight is at a large angle to this disk, the number of stars visible down to a certain brightness limit only increases slowly in this direction.
The counts show that at magnitude 20  , there are already more galaxies than stars, and at magnitude The detection limit for galaxies in this photo is at about magnitude The counts also indicate that the WFI has recorded a total of nearly , galaxies in this single field - many of which in turn contain more than , million stars. If the area density of galaxies were the same in all directions, this would mean that the total number of galaxies in the entire sky, brighter than blue magnitude The bright and straight line that extends from the bottom to the right edge in ESO Press Photo eso a is the trail of an earth-orbiting artificial satellite that passed through the telescope's field-of-view during one of the exposures.
There is also another, fainter trail from another satellite in the upper left quadrant, best visible in the High-Res version of this photo. Light pollution by satellites is an increasing problem in astronomical wide-angle imaging. Very remote and extremely dark sites such as Paranal and La Silla in the Chilean Atacama desert are not exempt from this. Such artifacts can be removed by means of advanced computerized image processing, but always at the loss of some scientific information. The Milky Way Galaxy is one of the largest obstacles to the detailed study of large-scale structures in the Universe - an observational approach with the aim of ultimately revealing the physical conditions at the time of the Big Bang.
The interstellar dust and high density of stars in our home galaxy severely obscure the view towards more distant objects. For instance, an intensive search on earlier photographic plates covering the field shown in ESO Press Photo eso c revealed only about 70 background galaxies, much less than what can be expected for such a rich cluster if it were seen in a sky field outside the Milky Way band. This led astronomers in the last century to introduce the term "Zone of Avoidance" for the Milky Way band in the sky.
Modern electronic detectors are able to register much fainter objects than those seen on the photographic plates.
A Special Edition of the Scientific American--One Hundred Thousand Copies
In the present field, cf. ESO Press Photo eso c , it is now possible to detect previously unseen dwarf galaxies in this rich cluster, in addition to some , stars in our own Galaxy. This illustrates well the recent instrumental progress for this type of observations. The sky region of ESO Press Photo eso c is of particular interest, as studies of the velocities of galaxies located in the cosmological neighbourhood of the Milky Way have indicated an unusual streaming motion in this direction.
This can be explained by the presence of a large-scale gravitational pull, and the existence of a huge concentration of mass, named the "Great Attractor" , has been inferred. At a distance of about million light-years, it is likely to be associated with or to form the central part of this "Great Attractor". They include some typical examples of the dynamical evolution of galaxies in clusters under the influence of their mutual gravitational forces. The effects range from cases of severe distortion of the shape ESO Press Photo eso d to "cannibalisation" by a giant elliptical galaxy of its smaller companions ESO Press Photo eso e.
Clusters of galaxies are some of the largest cosmic structures that are kept together by the combined gravitational pull of its constituents.
A.24 Compare numbers up to one hundred thousand
They frequently extend over many millions of light-years and are usually again grouped to the hierarchically next-higher level of structure, the so-called superclusters. Superclusters, in turn, often line up in extended filaments, hundreds of millions of light-years long; together, they form the foam- or sponge-like texture of the observable Universe. It contains many hundreds of individual galaxies. The most prominent is a large and bright galaxy, close to the center. The mass of this galaxy is more than 10 12 times that of our Sun. According to Hubble's law for the expansion of the Universe, this places the cluster at a distance of about million light-years.
Just say the number and then add the word "percent". To read a sum of money, first read the whole number, then add the currency name.
If there is a decimal, follow with the decimal pronounced as a whole number, and if coinage has a name in the currency, add that word at the end. Note that normal decimals are not read in this way. These rules only apply to currency. Just read out the number, followed by the unit of measurement, which will often be abbreviated in the written form.
Reading years in English is relatively complicated. In general, when the year is a four digit number, read the first two digits as a whole number, then the second two digits as another whole number. There are a few exceptions to this rule. Years that are within the first years of a new millenium can be read as whole numbers even though they have four digits, or they can be read as two two-digit numbers.
Millennia are always read as whole numbers because they would be difficult to pronounce otherwise. New centuries are read as whole numbers of hundreds. We do not use the word "thousand", at least not for reading years within the past years.
Years that have just three digits can be read as a three digit number, or as a one digit number followed by a two-digit number. Years that are a two digit number are read as a whole number. You can precede any year by the words "the year" to make your meaning clear, and this is common for two and three digit years.
- Oh Bess, Oh Wheres My Bess.
- História da Literatura Portuguesa – Idade Média (Portuguese Edition).
- One Hundred Thousand in Fresh Notes by Wax on Spotify;
- Palmito dEvian (Littérature Française) (French Edition).
- The Paper Factory (Michael Berg Book 1);
- Foul Deeds and Suspicious Deaths in Cardiff;
- The Obsidian Blade (Klaatu Diskos).
Years before the year 0 are followed by BC, pronounced as two letters of the alphabet. There are several ways to pronounce the number 0, used in different contexts. Unfortunately, usage varies between different English-speaking countries. These pronunciations apply to American English. Skip to main content. English grammar Determiners Quantifiers.