Tag Archives: Pluto

New Horizons — on its way to Pluto — will take a look at a different Kuiper Belt object in January 2015.

New Horizons — on its way to Pluto — will take a look at a different Kuiper Belt object in January 2015.

The encounter will take place at a range of about 75 million km, a distance somewhat subject to change depending on how the probe makes its course correction. At such a great distance, New Horizons will not be able to discern features on the surface of the KBO, nor will it be able to make spectroscopic observations to try to determine the composition of the surface material.

However, New Horizons will be in an excellent position to look for small, close-in moons around the object. It will also be in a position to observe the object’s phase curve, which is a measure of how the reflectivity of the surface changes as a function of viewing angle. This will reveal a great deal about the fluffiness of the surface material (note – fluffiness is a technical term meaning, roughly, “the opposite of dense”). These two observations cannot be made from Earth, even with the most powerful telescopes available.

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Pluto’s atmosphere is expanding, and scientists don’t know why

Pluto’s atmosphere is expanding, and scientists don’t know why.

Pluto travels along a highly elliptical path and last passed closest to the sun in 1989. Many planetary scientists expected the atmosphere to shrink as the icy orb began receding from the sun’s warmth. The unanticipated expansion may be related to changes in the darkness of the orb’s surface a decade or so ago, which may have caused the surface ices to absorb more solar radiation and more efficiently evaporate. Or, Greaves suggests, long-term variations in the sun’s ultraviolet output, changes linked to the roughly 11-year cycle of solar activity, may be playing a role.

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When is an Asteroid Not an Asteroid?

When is an asteroid not an asteroid?

The layered structure of Vesta (core, mantle and crust) is the key trait that makes Vesta more like planets such as Earth, Venus and Mars than the other asteroids, McCord said. Like the planets, Vesta had sufficient radioactive material inside when it coalesced, releasing heat that melted rock and enabled lighter layers to float to the outside. Scientists call this process differentiation.

This question immediately demonstrates once again the terrible mess the International Astronautical Union made when it decided several years ago to define what makes a planet, and came up with a definition that simply doesn’t work. For if Vesta should be considered a planet, why not Pluto?

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Pluto’s ice: 97% nitrogen, 3% methane

More results from the press conference going on right now at the 42nd meeting of the AAS Division for Planetary Sciences:

Pluto’s surface ice is made up of 97% nitrogen, 3% methane, while the surface of the Kuiper Belt object Eris (which is larger than Pluto) is even more rich in methane, with a make up of 90% nitrogen and 10% methane. Both measurements go down to a depth of about 10 inches. To see the abstract for this result, go here.

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