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Palomar

Member

From: USA

Registered: 2002-05-30

Posts: 9,734

Re: Charon Occults a Star - ...yeah, as in *Pluto's* moon!

*This merits its own thread, IMO:

http://www.spaceref.com/news/viewpr.htm … 46]Amazing

This is only the 2nd time scientists have observed Charon -- 4 billion miles away -- occult a star; the last time was 25 years ago. 

In addition to assessing whether Charon has an atmosphere, the team expects to get a new, accurate value for Charon's radius and determine how round it is.

The occultation occured on the night of July 10 - 11.  They'd waited years for this opportunity and it all came together.  :up:

From just how the light dimmed and brightened, the MIT-Williams consortium will look for signs that Charon has an atmosphere. It has very little mass, so has little gravity to hold in an atmosphere, but it is so cold (being some 40 times farther from the sun than the Earth, and thus about 4 billion miles away) that some gases could be held in place by the small amount of Charon's gravity.

That'd be awesome if it were proven true. 

Lots of work/planning involved:

Since the star that was hidden is so far away, it casts a shadow of Charon that is the same size as Charon itself, about 1,200 kilometers in diameter. To see the event, the distant star, Charon, and the telescopes in Chile had to be perfectly aligned. All these telescopes were in clear weather and successfully observed the occultation...The team had more than 100 square meters (about 1,000 square feet) of telescope surface facing Charon, Pluto and the star beyond them-a noticeable fraction of the world's total telescope area.

Congratulations to them. 

--Cindy

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We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...

--John Sladek (The New Apocrypha)