NASA-International Space Station

In a new research that involved the mapping of the shape of the galactic dark matter, astronomers have determined that the halo of dark material surrounding our Milky Way Galaxy is shaped something like a gigantic, compressed cosmic beach ball.

This result is significant because it is the first time that the three-dimensional shape of an individual dark-matter halo has been convincingly measured.

Dark-matter haloes account for over 70 percent of the mass in galaxies such as the Milky Way, but this dark matter is hidden; all we see when we look up in the sky is the small amount of stars and gas sitting in the centers of these haloes.

It might not be probable to detect it through normalmeans, but dark matter obeys the laws of gravity and tugs on small dwarf galaxies as they orbit around the Milky Way.

By observing the orbits that these dwarf galaxies follow, astronomers can infer where the dark matter must be using Newton's law of gravity.

While it would take approximately a billion years to watch a typical dwarf galaxy orbit just once around our home galaxy, dwarf galaxies get shredded by tidal forces as they orbit the much more immense Milky Way and leave stars like breadcrumbs along their path.

Using observations of such tidal debris from a dwarf known as the Sagittarius Dwarf Galaxy, astronomers have been able to rebuild the orbit of Sagittarius and derive models for the Milky Way and its dark-matter halo.

But, these models had met an impasse, as diverse parts of the orbit suggested wildly different solutions.

In September 2009, Law and colleagues Majewski and Johnston recommended a solution. By allowing the dark matter halo to be triaxial - that is, to have diverse axis lengths in all three dimensions - it is probable to fit the entire orbit of Sagittarius simultaneously.

The planned solution suggests that the invisible dark-matter halo of the Milky Way can be visualized as some kind of cosmic 'beachball' that has been compacted sideways.

The fact that the 'beach ball' was compacted from the side came as a surprise.
It suggests that the dark matter halo and the disk of stars in the Milky Way are tilting roughly perpendicular to each other.

"We expected some amount of flattening based on the predictions of the best dark-matter theories, but the extent, and mainly the orientation, of the flattening was quite unexpected. We're pretty thrilled about this, because it begs the question of how our galaxy formed in its present orientation," said Law.

This infrared photograph of a region in the constellation Carina near the Milky Way was taken shortly after NASA's Wide-field Infrared Survey Explorer (WISE) expelled its cover. The "first-light" image shows thousands of stars and covers an area three times the size of the moon. WISE will take more than a million alike pictures covering the whole sky.

The image was captured as the spacecraft stared in a fixed direction, in order to help standardize its pointing system. The mission's analysis will be done while the satellite continuously scans the sky, and an internal scan mirror counteracts the motion to create freeze-frame images. The team is working now to match the motions of the spacecraft and the scan mirror accurately.

This eight-second revelation shows infrared light from three of WISE's four wavelength bands: Blue, green and red correspond to 3.4, 4.6, and 12 microns, respectively.

More information is online at http://www.nasa.gov/wise and http://wise.astro.ucla.edu/.

The Hubble Space Telescope has peered farther back in space and time than ever before to see baby galaxies that may have been created as little as 500 million years after the big bang.

Astronomers estimate that three recently identified galaxies, which are small and compact and glow a striking blue, are about 13.2 billion light years away. This means that their starlight was emitted about 13.2 billion years ago, when the Universe was only 4 per cent of its present age.

“With the rejuvenated Hubble and its latest instruments, we are now entering uncharted territory that is ripe for new discoveries,” said Garth Illingworth, of the University of California, Santa Cruz, who led the survey team. He told the American Astronomical Society conference, in Washington, that the efficient Hubble observatory provided an opportunity to “push back the frontiers”.

Further clues to the early Universe have been provided by another image, which combines pictures from Hubble’s new camera with a survey from 2004. It gives a panoramic vision of the sky with about 7,500 galaxies at diverse stages of evolution.

The earliest galaxies detected by Dr Illingworth’s team were pinpointed in August last year, following the fitting of the telescope’s new Wide Field Camera 3 (WFC3). The instrument was pointed at a section of sky known as the Hubble Ultra Deep Field, which was first surveyed in visible light in 2004 to provide one of the telescope’s most iconic images — dark sky teeming with more than 10,000 galaxies. The WFC3 instrument has now recurring the exercise for infrared light. The first analysis of the new 2009 Hubble Ultra Deep Field found substance that was formed about 600 million years after the big bang. Dr Illingworth’s team has now found proof that three galaxies in the image date to about 500 million years after the dawn of the Universe.

Marcella Carollo, another member of the research group, said: “They are the very building blocks from which the immense galaxies of today, like our own Milky Way, ultimately formed.”