The Planetary Society battled hard for New Horizons mission’s successful launch to Pluto. When its flyby of this classic solar system planet and its four tiny moons Styx, Nix, Hydra and Kerberos took place in July 2015 it revolutionized our understanding of this classic world.
Scientists are still processing the wealth of data New Horizons has sent back home, developing deeper insight into dwarf planets and Kuiper Belt objects. This volume serves as an essential guide to comprehending Pluto system.
What is pluto?
Pluto is an ice dwarf planet less than half the width of Earth and 100 times further from the Sun than our own planet is. Part of a region in space called the Kuiper belt, Pluto hosts more than 100,000 mini worlds containing comets.
New Horizons gave humanity its first close look at Pluto in 2015, returning with an abundance of data for scientists to pore over. One such data set concerns Sputnik Planitia basin’s heart-like shape – possibly evidence that once held frozen nitrogen ocean ice.
How did pluto get here?
In 1992, scientists made an amazing discovery: Pluto had near cousins in our Solar System’s outermost region – known as the Kuiper Belt. Scientists were uncertain if these mini worlds qualified as planets.
Astronomers were impressed to discover many features similar to Pluto on these worlds: giant ice sheets, towering mountains, icy plains with dark streaks that resemble snakeskin; all pointing toward adding these worlds as planets within our Solar System.
New Horizons took close-up images of one side of Pluto – its near side – as it zoomed past in July 2015. Now scientists are beginning to analyze these close-up shots.
What is pluto’s surface like?
Pluto is covered by an unpredictable mix of ridges, cracks and plains on its surface; however, the far side of this dwarf planet reveals a strikingly different terrain: unofficially named Sputnik Planitia after Earth’s first artificial satellite, this vast icy plain lacks any noticeable craters found elsewhere on Pluto, suggesting it could be quite young geologically speaking.
But Pluto may still harbor life, in a different form. At its frigid temperatures, water essential to life would freeze solid. But inside Pluto might be different: perhaps warmer interior temperatures might support an ocean made up of liquid water-ice. A future mission could provide further information.
What is pluto’s atmosphere like?
Pluto has an atmosphere composed mostly of nitrogen, with trace amounts of methane. Methane absorbs heat from sunlight to heat the atmosphere above Pluto’s surface before radiating away and cooling its surroundings again.
Pluto’s atmosphere varies with altitude. Astronomers can measure this variation through an observation of “light curves,” which demonstrate how illumination dims as you ascend into its atmosphere.
New Horizons discovered in 2015 that Pluto has an atmosphere, suggesting mountain-like features in its light curve and suggesting there may be mountains nearby. Furthermore, New Horizons saw gases spreading thousands of miles out from Pluto’s atmosphere – suggesting its atmosphere may be much thinner than expected by scientists.
What is pluto’s moons like?
Astronomers studying images of Pluto from the NASA/ESA Hubble Space Telescope have discovered four small moons orbiting its dwarf planet that spin at unpredictable rates – Styx, Nix, Kerberos and Hydra appear to defy Pluto and Charon’s influence to maintain equilibrium on them.
Hydra is one of the fastest rotators of this group and features roughly football-shaped surfaces covered with craters. Through observations during New Horizons flyby last July, astronomers realized that high spin rates on Hydra were not due to forces like gravity; rather they believe resonances between moons may be responsible; their results have been published in Nature on June 4.
What is pluto’s future?
The New Horizons mission has provided further evidence of Pluto as an ice world, including surface fractures, possible cryovolcanoes, and no trace of an ancient equatorial bulge. But its subsurface ocean remains unknown due to radioactive decay of its frozen materials producing heat that must be dealt with.
Pluto orbits far into space within what is known as the Kuiper Belt. This disc-shaped zone contains hundreds of thousands of rocks and ice objects; once considered an actual planet but downgraded to dwarf status by scientists in 2006.
Scientists hope to send another spacecraft, this time an orbiter, to Pluto. NASA is studying its attributes, feasibility and costs of such an expedition.