Level 1 — Absolute Beginner
Scientists find comets in a far away star system. Comets are balls of ice and dust that move around a star.
The star system is called PDS 70. It is very young, only about 5.5 million years old. It is far from Earth, about 370 light years away.
Two big planets are in this system. Their names are PDS 70b and PDS 70c. Both planets are still growing.
Some comets fly close to the star. The ice on the comets turns into gas. This gas carries water toward the new planets.
- comet
- a ball of ice and dust that moves around a star
- star system
- a group of planets and other objects that orbit one star
- ice
- water that is frozen and hard
- gas
- a substance, like air, that is not solid or liquid
- planet
- a large round object in space that orbits a star
- water
- a clear liquid that living things need
- young star
- a star that formed a short time ago, in space terms
- telescope
- a tool used to see far away objects in space
Level 2 — Elementary
Astronomers at Lund University in Sweden have found new evidence about how water reaches young planets. They studied a distant star system called PDS 70, which is about 370 light years away in the constellation Centaurus.
PDS 70 is a young star, only about 5.5 million years old. It already has two confirmed planets, PDS 70b and PDS 70c, both still forming as gas giants. These were among the first planets ever directly imaged while still forming, using the European Southern Observatory's Very Large Telescope in 2018 and 2019.
Earlier, the James Webb Space Telescope had already detected water close to the star, in the inner part of the disk of gas and dust that surrounds it. Now the Lund team has found a likely explanation: changes in sodium gas in front of the star suggest that icy comets are passing close by and turning into vapor.
The researchers modeled the paths of these exocomets and found that the system's gas giant planets can pull distant icy objects off course, sending them falling toward the star. As the ice heats up and turns to gas, it can spread water toward the region where rocky planets are forming, similar to what may have happened in our own early Solar System.
- astronomer
- a scientist who studies stars, planets, and space
- exocomet
- a comet that orbits a star other than our Sun
- disk
- a flat, round area of gas and dust surrounding a young star
- sodium
- a chemical element that can be detected as a gas in space
- vapor
- a gas formed when a liquid or solid, such as ice, is heated
- gravity
- the pulling force between objects with mass
- gas giant
- a large planet made mostly of gas, rather than rock
- rocky planet
- a planet made mostly of solid rock and metal, like Earth
Level 3 — Intermediate
A team of astronomers at Lund University in Sweden has uncovered compelling evidence that exocomets, comets orbiting a star other than our own Sun, are transporting water toward the inner region of a young planetary system known as PDS 70, located roughly 370 light years from Earth in the constellation Centaurus.
PDS 70 is classified as a T Tauri star, a type of young star still in the early stages of its evolution, estimated to be only about 5.5 million years old. The system hosts two confirmed planets, PDS 70b and PDS 70c, both still in the process of forming as gas giants. They were among the very first planets ever directly imaged while still under construction, captured by the European Southern Observatory's Very Large Telescope in 2018 and 2019.
Prior observations from the James Webb Space Telescope had already revealed water in the disk close to the star, but the mechanism delivering that water remained unclear. The Lund researchers identified variations in sodium gas detected in front of the star as a likely signature of icy comets passing close by and vaporizing under the star's heat.
By modeling the orbits of exocomets throughout the system, the team found that the gravitational influence of the system's gas giant planets can perturb distant icy bodies, sending them careening inward toward the star. As their ice sublimates into gas, it can spread water toward the region where rocky, Earth like planets are believed to form, a process scientists suspect may parallel how comets helped deliver water to the young Earth billions of years ago.
- perturb
- to disturb the normal orbit or motion of an object through gravity
- sublimate
- to change directly from a solid, such as ice, into a gas
- T Tauri star
- a young, low mass star still in an early stage of formation
- careen
- to move swiftly, often in an uncontrolled direction
- mechanism
- a process by which something happens or is produced
- signature
- a distinctive sign or pattern that indicates something is present
- gravitational influence
- the effect one object's gravity has on the motion of another
- planetary system
- a star together with the planets and other objects that orbit it
Level 4 — Advanced
Astronomers at Lund University in Sweden have assembled a compelling case that exocomets, comets orbiting stars other than our own, are ferrying water toward the inner reaches of PDS 70, a young planetary system some 370 light years distant in the constellation Centaurus, offering a rare glimpse of a process that may echo the earliest chapters of our own Solar System's history.
PDS 70, a T Tauri star only about 5.5 million years old, a mere infant by stellar standards, already hosts two confirmed gas giants still in the throes of formation, PDS 70b and PDS 70c. Their direct imaging by the European Southern Observatory's Very Large Telescope in 2018 and 2019 marked a milestone in observational astronomy, capturing planets in the act of assembling themselves rather than inferring their presence indirectly.
The James Webb Space Telescope had already established that water lurks in the disk close to the star, yet the delivery mechanism remained conjectural until now. The Lund team's analysis pinpointed subtle variations in sodium gas silhouetted against the star as a telltale signature of icy bodies passing near enough to vaporize, a forensic approach that turns a faint spectral wobble into evidence of unseen comets.
Orbital modeling by the researchers indicates that the system's gas giants exert enough gravitational leverage to destabilize distant icy reservoirs, hurling fragments sunward, where their ices sublimate and disperse water toward the zone where rocky, terrestrial like worlds are thought to coalesce. It is a mechanism many planetary scientists suspect also operated in our own Solar System's infancy, when comets are believed to have seeded the young Earth with the water that now fills its oceans, a hypothesis to which this study, published in Nature Communications, lends fresh, distant support.
- ferry
- to transport something from one place to another
- conjectural
- based on guesswork or inference rather than direct proof
- spectral
- relating to the spectrum of light or wavelengths given off or absorbed by an object
- forensic
- using careful, evidence based analysis to establish facts
- leverage
- the power or influence to affect something, often through force
- reservoir
- a large supply or store of something, in this case icy bodies
- terrestrial
- relating to Earth or a planet with a solid, rocky surface
- coalesce
- to come together and form a single whole
Talk about this article with KatePractice this story's vocabulary in a real spoken conversation with your AI tutor