The National Aeronautics and Space Administration (NASA) has possibly found the answer to the streaks present in the hazy atmosphere in Pluto: gravity waves.

New Horizons flyby in 2015 gave a clearer picture of what Pluto looks like. Not only does it have an atmosphere, but it also tends to be hazy.

The latter point is the reason why NASA and New Horizons team decided to investigate further. With the help of computer simulations and observations of the data coming from the probe, they determined that it could be gravity waves.

Not Gravitational Waves

Some people may confuse gravitational and gravity waves, which is perfectly understandable.

Gravitational waves, which have been catapulted to bigger fame with the confirmation of its existence in February, are ripples in the space-time fabric. These waves are created after significant energetic events have occurred.

For example, the waves detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) operated by Caltech and Massachusetts Institute of Technology came from the collision and merging of two major black holes 1.3 billion years ago. The energy this event generated has finally reached Earth this year.

"[These are] not cosmological gravity waves, but atmospheric buoyancy waves," said New Horizons principal investigator Alan Stern.

As an analogy, imagine a rock thrown into a pond. The fluid, now displaced from its point of equilibrium, creates ripples as the rock travels across the surface. However, the farther the ripples go, the thinner and sparser they become.

In Pluto, or in this case, in its atmosphere, buoyancy lifts the air upward while gravity tries to restore the equilibrium. Further, the waves travel vertically or upward, coming from a lower altitude toward the higher one. Since density is inversely proportional to altitude, the ripples become more pronounced as they go up.

For the waves to happen, there must be a trigger, and in Pluto, these disturbances may include sublimation, or the conversion of gas to liquid, and deposition, or the transformation of gas to solid.

"As the waves travel up and down in the atmosphere, they compress and relax regions of haze particles," said Randy Gladstone, New Horizons team leader for Atmospheric Theme.

Aside from the appearance of haziness, it may be causing the flaring effect of the dwarf planet.

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