Baby galaxies sighted at dawn of universe

Astronomers have spotted the most distant galaxies known, from an era when the universe was just 4% its present age. Objects like these could be responsible for lifting the veil on the so-called cosmic 'dark ages', by making the universe transparent to light.
Because it takes light from distant galaxies billions of years to reach us, we see them as they were long ago, when the universe was much younger.

Previously, the most distant galaxy known had been found at a redshift of 7 – corresponding to a time when the universe was about 750 million years old (see First generation of galaxies glimpsed forming).
Now, astronomers led by Daniel Stark of Caltech in Pasadena, California, US, have found several galaxies at a redshift of about 9. A redshift of 9 corresponds to an era just 500 million years after the big bang – 4% the universe's present age of 13.7 billion years.

The team used the Keck II Telescope on Mauna Kea, Hawaii, US, to look for distant galaxies. They were able to improve the sensitivity of their search by taking advantage of a phenomenon called gravitational lensing, where the gravity of nearby objects bends and focuses light from more distant objects.
The team searched parts of the sky surrounding nearby galaxy clusters, where this lensing effect is most pronounced. They spotted two objects that appear to be at redshift 9, called Abell 68 c1 and Abell 2219 c1.
Their light appears to be that of excited hydrogen gas, redshifted by the expansion of the universe. But this alone is not enough for a firm identification, because excited oxygen from a closer object would shine at the same wavelength.
The astronomers were able to rule out the nearby object scenario because excited oxygen should also shine at a second wavelength, which these objects do not appear to do.

Since the astronomers only searched a minute fraction of the sky, even if only two of the objects are truly distant galaxies, this would suggest that these tiny galaxies were abundant in the early universe.
Rough calculations suggest that they would be abundant enough to play a significant part in lifting the veil on the cosmic dark ages. For most of the first few hundred million years of the universe's history, the universe was largely opaque to light because hydrogen atoms absorbed it everywhere.
Radiation from unknown sources later ripped electrons from the hydrogen atoms – a process called reionisation – so that it no longer absorbed light, making the universe transparent.

Previously, astronomers suspected that galaxies were rare 500 million years after the big bang, and that reionisation was largely carried out by objects at redshift 6, which corresponds to about 900 million years after the big bang (see Hubble heats debate over ionised universe).
But the detection of these objects suggests that these earlier objects may have a played a bigger role than previously believed

Scientists have reported the first conclusive evidence of water vapour in the atmosphere of an extrasolar planet. Before we load up the spaceships to search for life, however, consider the fact that this planet, HD 189733b, is larger than Jupiter, and orbits its parent star in just 2.2 days. That's hot hot water.
The discovery was made using the mighty Spitzer space telescope. The astronomers pointed Spitzer at the parent star, and measured the chemical consistency of its light as the planet passed in front - aka, transited. As the starlight dimmed - blocked by the planet - the chemical constituents of the star changed to show a distinctive pattern. Astronomers know that only water can absorb these specific wavelengths of infrared radiation.

This planet is certainly a "hot Jupiter". It contains 1.15 the mass of Jupiter (and 1.25 the diameter), but it orbits its parent star at a distance of only 4.5 million km. In comparison, our own Mercury is a distant 70 million km from the Sun.
It's close, so it's hot. Its atmospheric temperature is about 1000 Kelvin (more than 700 C). With this heat, all the water vapour in its atmosphere can't condense, rain or form clouds.
It's also tidally locked to its parent star, only showing one face to the star at all times (like the Moon and the Earth). This constant facing probably generates fierce winds that sweep around the planet from the day side to the night side.
Not the best place to find life, but still, an amazing discovery