Level 1 - Absolute Beginner
Pluto is a small, icy world far out in space. It has a huge, heart-shaped area of ice called Sputnik Planitia.
Scientists looked again at old pictures from a spacecraft called New Horizons. The spacecraft flew past Pluto in 2015.
The new look found something new. Liquid nitrogen may have come up through cracks in the ice, not long ago.
This is the first time scientists have seen signs of liquid moving on Pluto's surface. A scientist named Alan Stern led the study.
- dwarf planet
- a small round object in space that orbits the Sun but is not a full planet
- glacier
- a huge, slow-moving mass of ice
- spacecraft
- a vehicle built to travel and work in space
- liquid
- a substance, like water, that flows and is not solid or gas
- nitrogen
- a gas that makes up most of Earth's air; on Pluto it can freeze into ice
- crack
- a thin break or line in something solid
- surface
- the outside or top layer of something
- scientist
- a person who studies the world through careful research
Level 2 - Elementary
A new study of images from NASA's New Horizons spacecraft has found the first evidence that liquid recently flowed across the surface of Pluto, the distant dwarf planet.
The spacecraft flew past Pluto in July 2015 and photographed Sputnik Planitia, a massive glacier shaped like a heart that covers part of the surface.
Scientists re-examined dark, thin lines and patches near the northern edge of the glacier. They now believe these features were temporarily wetted by liquid nitrogen rising up from below the surface through cracks in the ice.
Pluto is far too cold for liquid nitrogen to fall as rain, so researchers say the liquid most likely seeps up from underground rather than falling from the sky. The study was led by Alan Stern, the mission's principal investigator, and published in The Planetary Science Journal.
- evidence
- facts or signs that show something is true
- distant
- far away
- massive
- very large in size
- feature
- a noticeable part or characteristic of something
- wetted
- made wet by a liquid
- seep
- to flow slowly through small openings
- underground
- beneath the surface of the ground
- principal investigator
- the lead scientist in charge of a research project
Level 3 - Intermediate
A reanalysis of imagery captured by NASA's New Horizons spacecraft during its July 2015 flyby has produced the first evidence of liquid recently flowing across Pluto's surface, according to a new study led by mission principal investigator Alan Stern.
The images, taken of the northern edge of Sputnik Planitia, a vast nitrogen-ice glacier that forms the western lobe of Pluto's famous heart-shaped feature, show city-sized convection cells separated by thin, dark, linear markings and more diffuse patches.
Researchers now interpret these dark features as having been intermittently wetted by liquid, most likely nitrogen, resembling the way terrestrial glaciers darken when saturated by water. Because Pluto's atmosphere and temperature make nitrogen rainfall physically impossible, the study concludes the liquid most plausibly emerges from below the surface through cracks at the glacier's edge.
The findings, published in The Planetary Science Journal, add to a growing picture of Pluto as a geologically active world rather than the frozen, inert body it was long assumed to be, reinforcing conclusions New Horizons has been building since its historic 2015 flyby.
- reanalysis
- the act of examining data again, often with new methods or perspective
- flyby
- a spacecraft mission that passes close to a celestial body without landing
- lobe
- a rounded, projecting part of a larger shape
- convection cell
- a pattern formed when heated material rises and cooler material sinks in a cycle
- intermittently
- occurring at irregular intervals; not continuously
- terrestrial
- relating to Earth or land, as opposed to other planets or the sea
- geologically active
- showing ongoing physical processes that reshape a surface, such as flowing liquid
- inert
- lacking the ability to move or change; inactive
Level 4 - Advanced
A fresh interpretation of imagery gathered during New Horizons' historic July 2015 flyby has yielded the first evidence of recently mobile liquid on Pluto's surface, a finding led by mission principal investigator Alan Stern that further upends the dwarf planet's earlier reputation as a geologically dormant relic of the outer solar system.
The relevant imagery, focused on the northern margin of Sputnik Planitia, the nitrogen-ice glacier constituting the western lobe of Pluto's iconic heart-shaped region, reveals city-scale convection cells bounded by thin, dark, linear markings interspersed with more diffuse discoloration.
Researchers now argue these dark features record episodes of surface wetting, most plausibly by liquid nitrogen, in a pattern analogous to terrestrial glacial darkening caused by meltwater saturation. Given that Pluto's frigid, low-pressure atmosphere renders nitrogen precipitation physically untenable, the study attributes the liquid's origin to subsurface emergence through fractures along the glacier's periphery rather than atmospheric fallout.
Published in The Planetary Science Journal, the conclusion extends a decade-long reassessment of Pluto's geologic character that New Horizons initiated at its 2015 encounter, cementing the dwarf planet's status as an active world whose interior processes continue to reshape its surface long after the era of active exploration by the spacecraft that discovered them.
- mobile
- capable of moving or being moved
- dormant
- temporarily inactive but capable of resuming activity
- relic
- an object or place that survives from an earlier time
- margin
- the edge or border of an area
- analogous
- comparable in certain respects to something else
- untenable
- not able to be maintained or defended against argument or fact
- periphery
- the outer edge or boundary of an area
- reassessment
- a renewed or revised evaluation of something
Talk about this article with KatePractice this story's vocabulary in a real spoken conversation with your AI tutor