Tag Archives: astronomy

The coldest, driest place on Earth would be a great place for an astronomical telescope

antarcticaNo human has ever set foot on Ridge A, 4,053m up the Antarctic Plateau. But a U.S.-Australian team collating satellite, ground-station, and climate-model data thinks it’s the coldest, driest place on the planet–and therefore the best place on Earth to set up an astronomical observatory.

The study revealed that Ridge A has an average winter temperature of minus 70C and that the content of the entire atmosphere there is sometimes less than the thickness of a human hair.

It is also extremely calm, which means that there is very little of the atmospheric turbulence elsewhere that makes stars appear to twinkle: “It’s so calm that there’s almost no wind or weather there at all,” says Dr Will Saunders, of the Anglo-Australian and visiting professor to UNSW, who led the study.

“The astronomical images taken at Ridge A should be at least three times sharper than at the best sites currently used by astronomers,” says Dr Saunders. “Because the sky there is so much darker and drier, it means that a modestly-sized telescope there would be as powerful as the largest telescopes anywhere else on earth.”

It’s not the first time Antarctica has been proposed as a site for stargazing:

Located within the Australian Antarctic Territory (81.5◦ S 73.5◦ E), the site is 144km from an international robotic observatory and the proposed new Chinese ‘Kunlun’ base at Dome A (80.37 S 77.53 E).

Interest in Antarctica as a site for astronomical and space observatories has accelerated since 2004 when UNSW astronomers published a paper in the journal Nature confirming that a ground-based telescope at Dome C, another Antarctic plateau site, could take images nearly as good as those from the space-based Hubble telescope.

Last year, the Anglo-Australian Observatory completed the first detailed study into the formidable practical problems of building and running the proposed optical/infra-red PILOT telescope project in Antarctica. The 2.5-metre telescope will cost over AUD$10million and is planned for construction at the French/Italian Concordia Station at Dome C by 2012.

I confess I haven’t read Kim Stanley Robinson’s novel Antarctica, but I’d be surprised if he missed this. But writers looking for a setting should find the neighborhood isn’t too crowded. Bring your mittens.

[Image: Antarctic Peninsula, giladr]

Pluto has a posse

Pluto and its moonsIf you’re among the body of people who decried the demotion of poor little Pluto, take heart – it (he?) may end up reinstated some time soon:

If Pluto is reinstated, it will probably be thanks to discovery rather than debate. Mark Sykes of the Planetary Science Institute in Tucson, Arizona, believes that revelations within and beyond our solar system over the coming years will make the IAU’s controversial definition of a planet untenable. “We are in the midst of a conceptual revolution,” he says. “We are shaking off the last vestiges of the mythological view of planets as special objects in the sky – and the idea that there has to be a small number of them because they’re special.”

Sykes believes that missions currently en route to Pluto and the asteroid Ceres, which orbits the sun between Mars and Jupiter, will reveal these dwarf planets as active and intricate worlds. Meanwhile, astronomers may find distant objects as large as Earth which the IAU would not define as planets.

Sykes is among those who prefer a simple and inclusive definition of planet status: if an object is big enough for its own gravity to squeeze it into a rounded shape, then call it a planet. That would make a planet of Pluto again, as well as Ceres and a growing number of other bodies.

All this debate around nomenclature just goes to point out that we’ve a lot still to learn about our own backyard – and that the pace of discovery is picking up. I’m hoping the public interest in space doesn’t fade out after the Moon landing anniversary; even if we can’t go to these places ourselves, I think it’s important for us to think and learn about the universe beyond our gravity well. [image courtesy NASA]

Oddball galaxy discovered

The Centaurus A galaxySeems there’s always something new to discover in the field of astronomy. The latest nugget of cosmological excitement is a tiny, dark-matter-free and closely-packed galaxy out in the direction of the Sombrero:

“It was only the size of a star cluster – which typically contain about one million stars – but it shone as brightly as a small galaxy. This indicated the object was an ultra-compact dwarf galaxy, a very unusual object, possibly containing 10 million stars,” he said.


“There is much debate in the astronomical community about how these things form. The prevailing theory is that they are dwarf galaxies that have been stripped of their outer halo of stars by the gravitational forces of the large parent galaxy, leaving only the bright inner core of stars. But we think it may be something else: a massive star cluster that has formed independently,” Hau explains.

Another unusual aspect of the ultra-compact dwarf galaxy is that it is very old – perhaps 10 billion years, indicating it was formed in the early stages of the universe, when things were all the more violent and energetic. Furthermore it appears to consist mainly of stars, rather than the still-enigmatic dark matter, which dominates the mass of most galaxies.

Small it may be, but SUCD1 is hardly peaceful, spitting out a powerful stream of X-rays. The team believes this to be the first time that X-ray emissions have been clearly detected from an ultra-compact dwarf object.

So, not your average ball of stars, then. And it may well turn out to be a natural (if freakish) example of the way the universe evolved…

… but indulge me a minute here, OK? An object much smaller than a normal galaxy, but which shines as brightly as one; an unusual topography of stellar density; an absence of the dark matter we’re accustomed to finding in such objects; a fierce source of X-ray emissions. You know that theory that says we’re most likely to find other advanced civilisations by looking for evidence of mega-engineering projects on the scale of Dyson Spheres and so on? Well, if I was one of the guys at SETI, I’d be booking some radio telescope time to scope out that little dwarf cluster.

Just sayin’. 😉

[Yeah, I know it’s probably just the first weird little galaxy of its type we’ve seen. But what can I say? I like Greg Egan novels. Image by thebadastronomer; it’s not of the galaxy in question, I’m afraid, but it is very pretty.]