Astronomers get closer look at Pluto

19:39, Jul 25 2012
Graham Blow
IN SIGHT: Wellington astronomer Graham Blow has been studying the occultations of Pluto from Carter Observatory.

Perfect conditions aligning over Wellington helped a global team of astronomers probe deep into Pluto's atmosphere.

The data will be crucial in forecasting where Pluto will be positioned and how far its atmosphere will extend in 2015 when NASA's New Horizons spacecraft does a flyby, after a decade-long voyage from Earth.

With 16 other sites in New Zealand and southeast Australia either clouded over or plagued by mechanical hitches, Kelburn's Carter Observatory was in ''exactly the right place, at the right time,'' lead astronomer Graham Blow said.

On June 4 Pluto passed in front of a faint star in the Sagittarius constellation - the event is known as an occultation.

Astronomers were expecting Pluto's atmosphere to partially obscure the star's light.

By monitoring changes in brightness as Pluto tracked past the star, astronomers hoped to determine whether the dwarf planet's atmosphere had contracted over the past few years.


But bad weather over most of eastern Australia and southern New Zealand only allowed data from three places in New Zealand - of these, the Carter Observatory's 41cm "Ruth Crisp" research-grade telescope benefited from ideal conditions in the capital.

A partial lunar eclipse darkened the night sky, making the observation even sharper.

Marc Buie, a scientist from the Southwest Research Institute in Boulder, Colorado, was assisted by Mr Blow and fellow Wellington astronomer Gordon Hudson.

The trio spent many hours and cold nights watching the occultations.

"It's wonderful that Wellington's amateur astronomers are able to use our Carter Observatory to participate in this coordinated international effort to explore more of our Solar System,'' observatory director Dr Sarah Rusholme said.

The telescope was donated to the observatory in the 1960s by New Zealand writer and philanthropist Ruth Crisp.

It is the third time the observatory has helped to detect and measure Pluto's atmosphere.


Contact Matt Stewart
Weather, science and environment reporter
Twitter: @smatape

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