five-decade-long era of solar system
reconnaissance that began with Venus and Mars in the early 1960s, continuing through first looks of Mercury,
Jupiter and Saturn in the 1970s and
Uranus and Neptune in the 1980s.
The July 14 flyby of Pluto will occur
50 years to the day after humans first
explored Mars with NASA’s Mariner 4
on July 14, 1965.
The Pluto system is unique in that
it contains the only binary planet
system in our Solar System. Pluto and
its largest moon Charon are what
scientists refer to as a double-dwarf
system. Pluto is currently classified as
a dwarf planet; while Charon is technically labeled a moon, both bodies
orbit the same point in space—a
point that isn’t within the circumference of either body.
Just like the Earth and the moon,
Pluto and Charon are tidally locked
in an orbital dance. The two orbit
like unbalanced weights on a dumbbell, each pulling on the four smaller
moons—Nix, Styx, Hydra, and Kerberos—that orbit the pair.
Using the Hubble Space
Telescope, the researchers conducted a comprehensive analysis of the
system and concluded that the two
largest moons, Nix and Hydra, wobble chaotically as they orbit. Styx and
Kerberos are expected to behave in
the same manner, although further
observations are needed to confirm
this prediction. We can tell that the
wobble is intensified by the fact that
the four moons are not spherical in
shape; they’re elongated, much like
a football.
Pluto was discovered in 1930 by
astronomer Clyde Tombaugh at the
Lowell Observatory in Flagstaff, AZ.
Shortly after the New Horizons mission
was launched in 2006—and after the
discovery of another Kuiper Belt Object (Eris) —astronomers voted to demote Pluto from its planetary status.
In honor of Tombaugh, a small New
Horizons carries some of his ashes on
board as he passed away before the
mission could get off the ground.
Astronomers want to know how
a system like Pluto and its moons
could form. The prevailing theory:
Pluto collided with another large
Artist’s impression of the New Horizons spacecraft
encountering a Kuiper Belt object.
Credit: JHUAPL/SwRI
body in the distant past, and much
of the debris from this impact went
into orbit around Pluto, eventually
coalescing to form Charon. Scientists
believe that a similar collision led to
the creation of Earth’s moon, so the
study of Pluto and Charon could
help scientists decipher the history of
our own planet.
Scientists want to figure out why
Pluto and Charon look so different. From Earth, the Hubble Space
Telescope and New Horizons, we
have seen that Pluto has a reflective
surface with distinct markings indicative of polar caps. Charon’s surface
is far less reflective, with indistinct
markings. Pluto has an atmosphere,
and Charon does not. Is the sharp
contrast between these two bodies
a result of evolution or is it due to
how they formed? New Horizons
will hopefully be able to solve this
mystery.
Artist’s concept of the New Horizons spacecraft as it approaches Pluto. The craft will study the global geology
and geomorphology of Pluto and large moon Charon, map their surface compositions and temperatures, and
examine Pluto’s atmosphere in detail.
Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)
04
04
Pluto’s density, size and surface
composition are strikingly similar to
those of Neptune’s largest satellite,
Triton — a captured body from the
Kuiper Belt. One great surprise of Voyager 2’s exploration of the Neptune
system was the discovery of ongoing
cryovolcanic activity on Triton. Will
Pluto or other KBOs display such
activity?
Another fascinating aspect of
www.RocketSTEM .org