When astronomers began spotting planets around distant stars in the mid-1990s, they were baffled. Many of these early discoveries involved worlds as big as Jupiter, or even bigger — but they orbit their stars so tightly that their “years” were just days long. Nobody could imagine how a Jupiter or anything like it could form in such a hostile location, where the radiation of the parent star would have pushed the light gas — which makes up most of such a planet’s mass — out to the farthest reaches of the solar system before it could ever coalesce.
Duane Hamacher a PhD student from Australia’s Macquarie University found an ancient meteor impact crater in a remote location of the Northern Territory by searching Google Earth and following clues from an ancient dreamtime legend told by the indigenous Arrernte people.
Mr Hamacher reported to the Sydney Morning Herald and other Australian newspapers that the Arrernte people’s legend about a star that fell into a waterhole called Puka in the valley where Kulaia, the serpent, lived – has led to the discovery of the ancient crater, which the research team he is part of propose to name Puka.
It happens only once in a blue moon — and scientists say a blue moon is exactly what we’ll see in the skies this New Year’s Eve.
Don’t expect an azure glow over our lunar satellite, however. The term “blue moon” simply refers to the second full moon in a calendar month, something that hasn’t happened on a New Year’s Eve for nearly 20 years, NASA says.
This year provided plenty of cosmic eye-openers for astronomers and casual stargazers alike. Neighborhood planets such as Mercury and Jupiter received makeovers in both a scientific and literal sense. The discovery of water on the moon and Mars provided clues to the past, not to mention hints for the future of space exploration. And a class of newly-detected “Super-Earth” planets around alien stars may ultimately prove more habitable than Earth. Here are the stories that stood out:
Read more SPACE.com — 9 Astronomy Milestones in 2009.
Sun-like stars have for the first time been found to harbour super-Earths – rocky planets larger than Earth but smaller than ice giants like Neptune.
Unlike stars previously known to harbour super-Earths, both of the stars discovered are similar to the Sun in size, age and other properties – for the first time suggesting that low-mass planets may be common around nearby stars.
Uranus spins on an axis almost parallel with the plane of the solar system, rather than perpendicular to it – though why it does this nobody knows. One theory is that the tilt is the result of a collision with an Earth-sized object, but this “hasn’t succeeded in explaining much of anything”, says Ignacio Mosqueira of the SETI Institute in Mountain View, California. Why, for example, are the orbits of Uranus’s 27 known moons not also tilted?
Most astronomers today believe that one of the most plausible reasons we have yet to detect intelligent life in the universe is due to the deadly effects of local supernova explosions that wipe out all life in a given region of a galaxy.
While there is, on average, only one supernova per galaxy per century, there is something on the order of 100 billion galaxies in the observable Universe. Taking 10 billion years for the age of the Universe (it's actually 13.7 billion, but stars didn't form for the first few hundred million), Dr. Richard Mushotzky of the NASA Goddard Space Flight Center, derived a figure of 1 billion supernovae per year, or 30 supernovae per second in the observable Universe!