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Explanation: Like grains of sand on a cosmic beach, individual stars of barred spiral galaxy NGC 1313 are resolved in this sharp composite from the Hubble SpaceTelescope's Advanced Camera for Surveys (ACS). The inner region of the galaxy i

s pictured, spanning about 10,000 light-years. Hubble's unique ability to distinguish individual stars in the 14 million light-year distant galaxy has been usedto unravel the fate of star clusters whose bright young stars are spread throug

h the disk of the galaxy as the clusters dissolve. The exploration of stars and

clusters in external galaxy NGC 1313 offers clues to star formation and star cluster evolution in our own Milky Way.

Farthest Galaxy Found, PerhapsBy Clara MoskowitzStaff Writerposted: 12 February 200811:38 pm ET

Astronomers have glimpsed what may be the farthest galaxy we've ever seen, provi

ding a picture of a baby galaxy born soon after the beginning of the universe.

Images taken with the Hubble Space Telescope have revealed the galaxy at almost13 billion light-years away, making it the strongest candidate for the most distant galaxy ever seen, said European Southern Observatory astronomer Piero Rosati, who helped make the discovery.

Since the galaxy is so far away, its light took ages to reach us, so what we seenow is a snapshot of how this galaxy looked 13 billion years ago. At that pointin time, the galaxy would have been newly formed, so the new observations provi

de a baby picture.

"We certainly were surprised to find such a bright young galaxy 13 billion years

in the past," said astronomer Garth Illingworth of the University of California, Santa Cruz, a member of the research team. "This is the most detailed look todate at an object so far back in time."

The young galaxy, called A1689-zD1, was born about 700 million years after the Big Bang that scientists think created the universe. For most of its early life,the universe languished in "dark ages" when matter in the expanding universe cooled and formed clouds of hydrogen. Eventually matter began to clump into stars and galaxies that radiated light, heating up the universe and clearing the fog.

Scientists think this newly discovered galaxy may have been one of the first toform and help end the dark ages.

"This galaxy presumably is one of the many galaxies that helped end the dark ages," said astronomer Larry Bradley of Johns Hopkins University in Baltimore, leader of the research team. "Astronomers are fairly certain that high-energy objects such as quasars did not provide enough energy to end the dark ages of the universe. But many young star-forming galaxies may have produced enough energy to end it."

The discovery was made possible by a natural magnifying glass the galaxy clusterAbell 1689, which lies between us and the distant galaxy. Abell 1689's gravity

is so strong it bends light that passes near it, acting like a giant zoom lens that magnifies what we see.

"This galaxy lies near the region where the galaxy cluster produces the highestmagnification," Rosati said, "which was essential to bring this galaxy within reach of Hubble and Spitzer."

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The discovery, announced today, will be detailed in the Astrophysical Journal.(space.com)

====TOTAL NUMBER OF STARS

by Glen Mackieastronomy.swin.edu.au

Glen Mackie is Lecturer, in the Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, Australia.

... the total number of stars in the universe is greater than all the grains ofsand on all the beaches of the planet Earth. - Carl Sagan

Carl Sagan (1934-1996) was Director of the Laboratory for Planetary Studies andDavid Duncan Professor of Astronomy and Space Sciences at Cornell University. Professor Sagan was a leading popularizer of science and astronomy in particular,

and presented the Cosmos television series and wrote the book (Cosmos, Random House: New York) based on the series.

Our eyes can only resolve about 5000 of the brightest stars, mostly close to ourSun, and typically within 1000 light years. (1 light year is the distance light

, travelling with a velocity of 300,000 kilometres per second, covers in 1 year)

Our Galaxy however, is probably greater than 100,000 light years in diameter. Hence we can resolve only a very small fraction of our Galaxy with our eyes. As well, whilst our view of the brightest stars is a magnificent panorama we do not get any sense of depth or relative distances of stars. For example, the two bright stars close together, alpha and beta Centauri, (commonly called The Pointers because they guide us to the nearby Southern Cross) are at very different distanc

es. Rigil Kentaurus and Hadar (their common names) are 4.3 and 490 light years distant, respectively. Hardly neighbours!

The faint smudge of light we call the Milky Way, easily visible on a dark night,is millions of very faint, distant stars lying in the disk of our Galaxy that o

ur eyes cannot resolve. Dark clouds of dust (microscopic pieces of carbon and silicon) dimms the light of many more stars. Apart from a few neighbouring galaxies (including the Large and Small Magellanic Clouds visible in the southern sky),that appear as faint, fuzzy blobs of light, our naked eye perception of the uni

verse is very myopic.

Our Galaxy, has approximately 400 billion stars. Carl used this number in the book based on his Cosmos television series and I'll stick with it. We define a billion as 10 to the power 9, or 1 with 9 zeroes following it, ie. 1,000,000,000. Big. Is our Galaxy average? Well, it's a spiral, a little less massive than our magnificent Local Group neighbour, Messier 31 in Andromeda. As far as spirals go,it's probably close enough to average. The other galaxies that exist in the uni

verse, large ellipticals and smaller irregular galaxies, tend to have more and less stars, respectively. I'll assume that, in terms of star numbers, our Galaxyrepresents the average galaxy.

What is the total number of galaxies in the universe? Sagan assumed 100 billion.Is that still valid? Recently the Hubble Space Telescope (HST) surveyed, to thefaintest levels yet detected, a small area of sky. Extrapolating from the numbe

r of galaxies detected by HST to that expected over the whole sky, I calculate 1

30 billion galaxies, slightly larger than Sagans estimate. Then the number of stars in the universe is 400 billion x 130 billion, or about 50,000 billion billion. A billion billion. That's 1,000,000,000,000,000,000. So, grasp the concept of

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a billion billion, then think of 50 thousand of those. Easy!

in three days, our Galaxy had moved another 0.2 billion kilometres towards the Virgo cluster of galaxies (located 650 billion billion kilometres away)