That distance nearly doubles just half a Pluto-year later, to 50 AU in 2123.
This periodic reappearance of fresh frost takes place every Pluto-year (248 Earth-years) and is the reason that Pluto is one of the most reflective surfaces in the Solar System.
Did you put together this petition because you're pro-Pluto and you want the decision reversed?
Which makes us wonder if -- is Pluto trying to convince the International Astronomical Union to reverse its decision?
ENGADGET: Alt-week 7.28.12: social mathematics, Pluto's moons and humans-on-a-chip
And since the number of objects in the catalogue is fast approaching 10, 000, he advocates making Pluto the first five-figure minor planet.
And you look at planets like Mercury that have very, very thin atmosphere - similar to Pluto's atmosphere, and it's a different situation then for the Earth or Jupiter, which is substantially atmosphere.
Water-ice covers Charon, while Pluto's surface is predominantly nitrogen frost with traces of methane and carbon monoxide ices.
But first, we haven't heard the last about the ignominious vote last month to strip Pluto of its place in our solar system - kicked out of the planetary lineup by a group of astronomers because it doesn't fit the new definition of what a planet is.
The Sun enters Scorpio and aspects every slower planet except Pluto, and there's an intense Mars-Jupiter opposition.
ENGADGET: Editorial: Turning point for the tortoise and the hare
The "new" Solar System agreed at the IAU's General Assembly has eight planets - Mercury to Neptune - and at least three dwarf planets: Pluto, Eris and the largest asteroid in the Solar System, Ceres.
BBC: NEWS | Science/Nature | Astronomers name 'world of chaos'
But part of the problem with the definition - I mean, as an example - is that if you look at Mars - if Mars - if we discovered a Mars-sized object out beyond the orbit of Pluto, it couldn't be a planet, because over the age of the solar system it wouldn't have time to clear its orbit.
In 1989, Pluto was as close to the Sun as it gets during its long year - less than 30 astronomical units (AU), or 30 times the distance between Earth and the Sun.
Another solution, that championed by Brian Marsden of the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts, would be to give Pluto a sort of astronomical dual citizenship.
But most of the history of the solar system--this is why the comet is so important--most of the history of this comet was spent out beyond Neptune, out where Pluto is at the very edge of the solar system, what we call the Kuiper belt.
应用推荐